RARE DISEASE
Malignant hyperthermia of anesthesia
Malignant hyperthermia of anesthesia
Malignant hyperthermia of anesthesia
Synonyms: Hyperthermia of anesthesia
Synonyms: Hyperthermia of anesthesia
Synonyms: Hyperthermia of anesthesia
Drug discovery
3
drugs
With orphan designations
Overview
Malignant hyperthermia (MH) is a life-threatening pharmacogenetic disorder triggered by volatile anesthetics and succinylcholine, causing uncontrolled skeletal muscle hypermetabolism. It stems from RYR1/CACNA1S gene mutations, leading to excessive calcium release in muscle cells. Acute presentations include hypercapnia, tachycardia, rigidity, hyperthermia (>39°C), and acidosis. Immediate trigger cessation, IV dantrolene (2.5–10 mg/kg), and active cooling are critical to reduce mortality from 70% to <5% [1][7][11][12].
Therapies
Emergency: Stop triggers; administer dantrolene (2.5 mg/kg IV bolus, repeated until resolved); hyperventilate with 100% O₂; active cooling (iced fluids, surface cooling) [3][8][17].
Prophylaxis: Use charcoal filters to prep anesthesia machines (<5 ppm volatile agents); avoid triggers in confirmed/suspected cases [1][7].
Categories: rare genetic diseases, rare neurological diseases
Research Papers
878 drug discovery papers about Malignant hyperthermia of anesthesia, with 2 first-in-class and 6 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
878 drug discovery papers about Malignant hyperthermia of anesthesia, with 2 first-in-class and 6 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2026-07-28 | Cooperative roles of W882 and W996 in state-dependent dantrolene stabilization within the RyR1 P1 domain.
Dantrolene is a clinically approved therapeutic used to suppress abnormal calcium release associated with malignant hyperthermia linked to RyR1 mutations. Cryo-electron microscopy studies have revealed a putative dantrolene-binding cavity within the RyR1 P1 domain and highlighted several residues associated with ligand recognition. However, the dynamic molecular interactions governing ligand stabilization within this region remain incompletely understood. MM/GBSA calculations, conformational entropy analyses, and potential of mean force (PMF) profiling were employed to investigate the local binding dynamics of dantrolene within isolated RyR1 P1-domain complexes. Comparative analyses of the P1 domain from open- and closed-state conformations of RyR1 revealed that the closed-state complex provides a more stable binding environment characterized by lower backbone fluctuations, enhanced ligand-protein contacts, stabilization of a distal loop region (residues 1006-1028), and higher ligand dissociation barriers. Per-residue energetic decomposition and interaction analyses identified W882 and W996 as major contributors to ligand stabilization through cooperative hydrogen bonding and π-mediated interactions. Alanine substitution of these residues increased ligand conformational flexibility and substantially reduced the energetic barriers associated with ligand dissociation, whereas R1000 exhibited comparatively smaller contributions to overall binding stability. Overall, these computational findings are consistent with previous experimental observations and provide atomistic insight into the interaction networks and structural determinants underlying state-dependent stabilization of dantrolene in a cryo-EM-derived RyR1 P1-domain binding model.
2026-05-31 | Anesthesia Management in a Patient With a History of Fulminant Malignant Hyperthermia and a Homozygous RYR1 p.Arg530His Variant Undergoing Laparoscopic Surgery: A Case Report.
BACKGROUND Malignant hyperthermia (MH) is a rare but potentially fatal pharmacogenetic disorder triggered by volatile anesthetics or suxamethonium, most commonly associated with variants in the ryanodine receptor type 1 (RYR1) gene. Patients with confirmed or suspected MH susceptibility are advised to avoid triggering agents and undergo regional anesthesia or total intravenous anesthesia (TIVA). Remimazolam, an ultra-short-acting benzodiazepine approved in Japan for general anesthesia, has been shown in vitro not to increase intracellular calcium concentrations in cells expressing MH-associated RYR1 variants. However, clinical evidence regarding its safety in genetically confirmed MH remains limited. CASE REPORT An 80-year-old man with a history of fulminant MH at age 39, successfully treated with dantrolene, was scheduled for laparoscopic inguinal hernia repair. Previous calcium-induced calcium release testing confirmed MH susceptibility. Genetic analysis revealed homozygosity for the RYR1 c.1589G>A (p.Arg530His) variant, classified as likely pathogenic. Given his history and cardiovascular comorbidities, remimazolam-based TIVA was selected. Anesthesia was induced and maintained with remimazolam, remifentanil, and rocuronium under strict MH precautions, including immediate availability of dantrolene. Intraoperative end-tidal carbon dioxide, core temperature, and hemodynamics remained stable, with no signs of MH. Neuromuscular blockade was reversed with sugammadex, and recovery was uneventful without postoperative complications. CONCLUSIONS Remimazolam-based TIVA was successfully administered in a patient with genetically confirmed MH susceptibility carrying a homozygous likely pathogenic RYR1 variant. The perioperative course was uneventful, suggesting that remimazolam-based TIVA may be a feasible anesthetic approach in selected high-risk MH-susceptible patients, including those with severe prior episodes and significant cardiovascular comorbidities.
2026-05-26 | Beyond the first bout: Adaptations to repeated injuries across physiological and pathological conditions.
Skeletal muscle exhibits remarkable plasticity following injury, yet most research has focused on responses to a single bout of eccentric contractions. This review addresses adaptations to repeated eccentric contraction-induced injuries across physiological and pathological conditions, with emphasis on insights from preclinical rodent models. In healthy muscle, the repeated bout effect (RBE) reduces strength loss and accelerates recovery after subsequent bouts. However, these adaptations are highly condition dependent. Aging can attenuate the RBE, while dystrophic muscle remains vulnerable to repeated injury despite compensatory remodeling. Other factors, including but not limited to, chronic alcohol intake and malignant hyperthermia can influence these responses, though their effects vary and do not universally abolish adaptation. Collectively, these findings highlight that the trajectory of muscle adaptation depends on its physiological state and underlying pathology. Understanding these condition-specific mechanisms is essential for developing targeted strategies to optimize recovery, maximize adaptations, and preserve muscle health across diverse populations.
2026-04-11 | Use of total intravenous anesthesia with propofol and a vaporizer-free ventilator to prevent recurrence of malignant hyperthermia in a dog.
Malignant hyperthermia (MH) is a rare, life-threatening perioperative complication most commonly triggered by inhalant anesthetics or depolarizing neuromuscular blocking agents. Genetic variants affecting skeletal muscle are believed to underlie the susceptibility to MH. Although total intravenous anesthesia (TIVA) has been employed in human patients with MH susceptibility as a nontriggering alternative, comparable data and standardized protocols are limited in veterinary medicine. A 13-year-old spayed female Toy Poodle dog with a history of suspected MH during isoflurane anesthesia 4 years earlier, characterized by a rapid increase in body temperature (42.0 °C) and end-tidal carbon dioxide tension (PE´CO2), and successfully treated with active cooling and dantrolene administration, presented for treatment of an asymptomatic tongue mass. General anesthesia was planned to facilitate a thorough oral examination and biopsy. TIVA with propofol was performed to prevent MH recurrence, using a vaporizer-free ventilator. Following anesthetic premedication with buprenorphine (20 μg kg-1, intravenously) and atropine sulfate (25 μg kg-1, subcutaneously), anesthesia was induced with propofol to allow endotracheal intubation and maintained with a propofol variable rate intravenous infusion (0.4-0.5 mg kg-1 minute-1) under mechanical ventilation with 100% oxygen. Dantrolene was available but was not required. During the 37-minute anesthetic period, rectal temperature gradually decreased, and PE´CO2 remained stable. Inspired isoflurane fraction was undetectable during the perioperative period. Recovery was smooth, and postoperative blood tests revealed only mild creatine kinase elevation. Whole-genome sequencing of peripheral blood DNA revealed a missense variant in the ryanodine receptor gene (RYR1), identical to a known human MH-causing mutation (p.Arg2435His). This case suggests that propofol-based TIVA combined with a vaporizer-free ventilator can safely prevent MH recurrence in genetically susceptible dogs, highlighting the importance of eliminating all potential MH triggers in susceptible individuals.
2026-02-06 | Continuous Epidural Anesthesia for Living-related Renal Transplant in a Patient With Malignant Hyperthermia and Reduced Cardiac Function: A Case Report and Narrative Review of the Literature.
Kidney transplantation is most often performed under general anesthesia, with or without regional anesthesia for adjunctive pain control. Select patients may benefit from neuraxial anesthesia as their primary anesthetic, especially when their comorbidities preclude the safe provision of general anesthesia. In this report, we describe the case of a 75-year-old man with malignant hyperthermia and ischemic cardiomyopathy who underwent a living-related kidney transplant under epidural anesthesia. Intraoperative hemodynamics were stable, and pain control was excellent; the surgeon reported no difficulties during the procedure. Allograft function was immediate and robust, and postoperative pain was well-controlled. The patient denied any side effects from the epidural block. We then summarize relevant literature from the 1960s through the present time regarding neuraxial blocks as the primary anesthetic for kidney transplantation and address considerations around the performance of neuraxial anesthesia in patients with end-stage renal disease. We also discuss common hesitations with neuraxial anesthesia and summarize the available data on patient-centered outcomes. Neuraxial anesthesia affords benefits of similar hemodynamics, similar allograft function, and improved postoperative pain control for patients undergoing kidney transplantation, compared to general anesthesia. Spinal, epidural, or combined spinal-epidural techniques should be given consideration when designing an anesthetic for patients with certain comorbidities that heighten the risk of a general anesthetic.
gene therapies
2026-03-30 | Advances in malignant hyperthermia: pathophysiology, diagnosis and management
Malignant hyperthermia (MH) is a rare genetic disorder triggered by volatile anaesthestics and depolarizing muscle relaxants like sevoflurane, desflurane, and succinylcholine. It is mainly associated with pathogenic variants in the RYR1 and CACNA1S genes that disrupt calcium regulation in skeletal muscles, causing uncontrolled calcium release from the sarcoplasmic reticulum and a hypermetabolic crisis with rhabdomyolysis, muscle rigidity, hypercapnia, hyperthermia, and multiorgan failure. Since its first clinical description in the 1960s, clinical signs such as tachycardia, rising end-tidal CO₂ (ETCO₂), and sudden hyperthermia remain essential for detection. Diagnosis relies on invasive muscle contracture tests like the Caffeine-Halothane contracture test (CHCT) and in vitro contracture test (IVCT). Next-generation sequencing (NGS) identifies mutations in RYR1, CACNA1S, and related excitation–contraction coupling genes. Despite incomplete genotype-phenotype correlations, mechanisms including oxidative stress and sodium-calcium channel dysregulation improve understanding of MH susceptibility. Management requires immediate cessation of triggering agents, intravenous dantrolene, and supportive care including cooling, correction of acidosis, electrolyte control, and monitoring of cardiac and renal complications. Patients should be monitored for recurrence within 24 hours and receive genetic counselling, medical alert identification, and family screening due to autosomal dominant inheritance. Emerging research explores CRISPR/Cas9 correction of RYR1 mutations, antisense oligonucleotide therapy to suppress mutant transcripts, and antioxidants N-acetylcysteine and Trolox to reduce reactive oxygen species-mediated muscle injury; animal studies show improved calcium regulation but human trials are needed. Preventive measures include temperature and ETCO₂ monitoring, regional anaesthesia in obstetrics, and total intravenous anaesthesia, when necessary, supported by collaboration among anaesthesiologists, geneticists, intensivists, and surgeons.
2025-07-25 | Calsequestrin-1 Deficiency Induced Malignant Hyperthermia-Like Skeletal Injury through Mitochondrial Disorder.
Calsequestrin-1 (CASQ1) is a candidate gene defect for malignant hyperthermia (MH) with significant skeletal muscle symptoms and injury, in which mitochondrial dysfunction may play an important role. However, the mechanisms underlying the mitochondrial changes are unknown. In this study we aimed to investigate the possible mechanisms for mitochondrial disorder using calseguestrin-1 knockout (Casq1-KO) mice. Casq1-KO mouse skeletal muscle injury was detected by the measurement of grip strength, and hematoxylin-eosin (H&E) and Gomori immune-staining. Mitochondrial function was evaluated by assessments of membrane potential (MMP), ATP production, and mitochondrial Ca2+ level. Western blot and malondialdehyde (MDA) assays were used to evaluate mitochondrial oxidative stress. AAV9-carrying CMV-Casq1 gene transfection was applied to confirm the effect of Casq1 deficiency on the skeletal muscle. The results showed that Casq1-KO mice exhibited obvious skeletal muscle dysfunction, structural change, and promotions of reactive oxygen species (ROS) production and its signal pathway activation. Significant decreases in ATP production and MMP, and an increase in mitochondrial Ca2+ level were observed in Casq1-KO skeletal mitochondria compared with those of WT. Interestingly, the expression of mitochondrial Ca2+ channel (MICU1), an important mitochondrial Ca2+ regulatory protein, was remarkably reduced in Casq1-KO skeletal mitochondria. Transduction of AAV9-CMV-Casq1 into Casq1-KO skeletal muscle recovered the Casq1 and MICU1 expression, mitochondrial Ca2+ level, MMP, and ATP production, with significant mitigation of skeletal oxidative stress and injuries. In conclusion, Casq1 deficiency or dysfunction could induce skeletal muscle injuries directly. Depressed MICU1 expression with an increased mitochondrial Ca2+ and ROS production may contribute significantly to the skeletal myopathy in malignant hyperthermia-like skeletal syndrome.
2022-06-13 | Variants in ASPH cause exertional heat illness and are associated with malignant hyperthermia susceptibility
Abstract Exertional heat illness (EHI) and malignant hyperthermia (MH) are life threatening conditions associated with muscle breakdown in the setting of triggering factors including volatile anesthetics, exercise, and high environmental temperature. To identify new genetic variants that predispose to EHI and/or MH, we performed genomic sequencing on a cohort with EHI/MH and/or abnormal caffeine-halothane contracture test. In five individuals, we identified rare, pathogenic heterozygous variants in ASPH , a gene encoding junctin, a regulator of excitation-contraction coupling. We validated the pathogenicity of these variants using orthogonal pre-clinical models, CRISPR-edited C2C12 myotubes and transgenic zebrafish. In total, we demonstrate that ASPH variants represent a new cause of EHI and MH susceptibility.
2019-02-15 | Masseter muscle rigidity and the role of DNA analysis to confirm malignant hyperthermia susceptibility
Malignant hyperthermia (MH) is an uncommon, autosomal dominant disorder of skeletal muscle, triggered by inhalational anaesthetics or depolarizing muscle relaxants. Masseter muscle rigidity (MMR) can be regarded as potentially a preceding sign for an MH reaction. Susceptibility to MH can be determined by the in vitro contracture test (IVCT) or DNA analysis where a familial variant is known. Our aims were to review patients with MMR, where IVCT and DNA analysis had been undertaken, to determine if DNA analysis could be used as an initial screening tool for MH susceptibility, and, by reviewing standard monitored variables (SMVs), to determine if any clinical characteristics could be used to differentiate between MMR patients who are MH susceptible (MHS) and those who are not. Patients with MMR were identified from the Palmerston North Hospital MH Reactions Database. IVCT and DNA analysis results were documented. DNA testing was performed retrospectively in the majority of patients as many patients had presented before DNA analysis was available. Forty-one patients were analysed. Fourteen were DNA positive/IVCT positive and six DNA positive only (48% in total), seven were IVCT positive/DNA negative and 14 were IVCT normal. Increased creatine kinase (>18,000 units/L) was consistent with MH susceptibility. Severity of MMR was not linked to MH susceptibility. This study confirmed that DNA analysis can be used as a first-line test for MH susceptibility in patients presenting with MMR (consistent with European MH Group recommendations). Creatine kinase was the only SMV that was significantly different between MHS and MH normal individuals.
2014-10-16 | Adenovirus-mediated expression of myogenic differentiation factor 1 (MyoD) in equine and human dermal fibroblasts enables their conversion to caffeine-sensitive myotubes.
Several human and animal myopathies, such as malignant hyperthermia (MH), central core disease and equine recurrent exertional rhabdomyolysis (RER) are confirmed or thought to be associated with dysfunction of skeletal muscle calcium regulation. For some patients in whom the genetic cause is unknown, or when mutational analysis reveals genetic variants with unclear pathogenicity, defects are further studied through use of muscle histopathology and in vitro contraction tests, the latter in particular, when assessing responses to ryanodine receptor agonists, such as caffeine. However, since muscle biopsy is not always suitable, researchers have used cultured cells to model these diseases, by examining calcium regulation in myotubes derived from skin, following forced expression of muscle-specific transcription factors. Here we describe a novel adenoviral vector that we used to express equine MyoD in dermal fibroblasts. In permissive conditions, transduced equine and human fibroblasts differentiated into multinucleated myotubes. We demonstrate that these cells have a functional excitation-calcium release mechanism and, similarly to primary muscle-derived myotubes, respond in a dose-dependent manner to increasing concentrations of caffeine. MyoD-induced conversion of equine skin-derived fibroblasts offers an attractive method for evaluating calcium homeostasis defects in vitro without the need for invasive muscle biopsy.
antibodies
2025-11-10 | Ca2+, ROS, IL-6, and p38 MAPK signaling loops underlying alterations in myotube formation induced by a severe MH/CCD mutation in RyR1.
Mutations in the gene encoding the skeletal muscle ryanodine receptor (RyR1) can result in muscle diseases, termed RyR1-related myopathies (RyR1-RM). Examples include malignant hyperthermia (MH), central core disease (CCD), and centronuclear myopathy (CNM). The muscles involved often have more (and mispositioned) nuclei than normal. A subset of the corresponding mutant proteins shows an overactive or leaky sarcoplasmic reticulum (SR) channel behavior that depletes the SR Ca2+ content and increases the level of cytosolic Ca2+. In addition, two remarkable effects of these RyR1 variants have been reported in cultured myogenic cells: enhanced expression of interleukin-6 (IL-6) and stimulation of myoblast fusion (myonuclei accretion). Here, we have investigated whether the latter effect is due to a possible IL-6-dependent autocrine loop. Toward this goal, we analyzed the impact of the overactive Y523S mutant compared with the wild-type RyR1 after expression in C2C12 cells. The results show that this mutation indeed drastically promotes myoblast fusion up to ∼300%. Moreover, this action depends on the sequential activation of SR Ca2+ release, store-operated Ca2+ channels, reactive oxygen species (ROS, cytosolic and mitochondrial), calpain, and calcineurin. In addition, a neutralizing antibody directed against IL-6 and a p38 inhibitor completely suppressed the stimulation of myoblast fusion. Furthermore, in RyR1-expressing cells, myotube formation was promoted by either exogenous IL-6 or conditioned medium obtained from the Y523S-expressing cells. These findings suggest an autocrine mechanism involving the interplay between Ca2+, ROS, IL-6, and p38 signaling pathways in controlling myonuclei density, which could be essential to explain the pathogenesis of RyR1-RM.NEW & NOTEWORTHY Overactive RyR1 mutant proteins are associated with muscle disease; interestingly, they increase the number of myonuclei when expressed in C2C12 cells. We discovered that this alteration depends on a Ca2+/ROS loop, which recruits calpain and calcineurin to stimulate the production of IL-6 and the subsequent autocrine activation of p38. Thus, disease-causing RyR1 mutations require an IL-6 autocrine system to alter myonuclear density. This novel mechanism could be critical to understanding the pathogenesis of congenital myopathies.
2010-06-22 | Store-operated Ca2+ Entry in Malignant Hyperthermia-susceptible Human Skeletal Muscle
In malignant hyperthermia (MH), mutations in RyR1 underlie direct activation of the channel by volatile anesthetics, leading to muscle contracture and a life-threatening increase in core body temperature. The aim of the present study was to establish whether the associated depletion of sarcoplasmic reticulum (SR) Ca2+ triggers sarcolemmal Ca2+ influx via store-operated Ca2+ entry (SOCE). Samples of vastus medialis muscle were obtained from patients undergoing assessment for MH susceptibility using the in vitro contracture test. Single fibers were mechanically skinned, and confocal microscopy was used to detect changes in [Ca2+] either within the resealed t-system ([Ca2+]t-sys) or within the cytosol. In normal fibers, halothane (0.5 mm) failed to initiate SR Ca2+ release or Ca2+t-sys depletion. However, in MH-susceptible (MHS) fibers, halothane induced both SR Ca2+ release and Ca2+t-sys depletion, consistent with SOCE. In some MHS fibers, halothane-induced SR Ca2+ release took the form of a propagated wave, which was temporally coupled to a wave of Ca2+t-sys depletion. SOCE was potently inhibited by "extracellular" application of a STIM1 antibody trapped within the t-system but not when the antibody was denatured by heating. In conclusion, (i) in human MHS muscle, SR Ca2+ depletion induced by a level of volatile anesthetic within the clinical range is sufficient to induce SOCE, which is tightly coupled to SR Ca2+ release; (ii) sarcolemmal STIM1 has an important role in regulating SOCE; and (iii) sustained SOCE from an effectively infinite extracellular Ca2+ pool may contribute to the maintained rise in cytosolic [Ca2+] that underlies MH. In malignant hyperthermia (MH), mutations in RyR1 underlie direct activation of the channel by volatile anesthetics, leading to muscle contracture and a life-threatening increase in core body temperature. The aim of the present study was to establish whether the associated depletion of sarcoplasmic reticulum (SR) Ca2+ triggers sarcolemmal Ca2+ influx via store-operated Ca2+ entry (SOCE). Samples of vastus medialis muscle were obtained from patients undergoing assessment for MH susceptibility using the in vitro contracture test. Single fibers were mechanically skinned, and confocal microscopy was used to detect changes in [Ca2+] either within the resealed t-system ([Ca2+]t-sys) or within the cytosol. In normal fibers, halothane (0.5 mm) failed to initiate SR Ca2+ release or Ca2+t-sys depletion. However, in MH-susceptible (MHS) fibers, halothane induced both SR Ca2+ release and Ca2+t-sys depletion, consistent with SOCE. In some MHS fibers, halothane-induced SR Ca2+ release took the form of a propagated wave, which was temporally coupled to a wave of Ca2+t-sys depletion. SOCE was potently inhibited by "extracellular" application of a STIM1 antibody trapped within the t-system but not when the antibody was denatured by heating. In conclusion, (i) in human MHS muscle, SR Ca2+ depletion induced by a level of volatile anesthetic within the clinical range is sufficient to induce SOCE, which is tightly coupled to SR Ca2+ release; (ii) sarcolemmal STIM1 has an important role in regulating SOCE; and (iii) sustained SOCE from an effectively infinite extracellular Ca2+ pool may contribute to the maintained rise in cytosolic [Ca2+] that underlies MH.
1996-09-01 | Role of Malignant Hyperthermia Domain in the Regulation of Ca2+ Release Channel (Ryanodine Receptor) of Skeletal Muscle Sarcoplasmic Reticulum
A fusion protein encompassing Gly341 of the skeletal muscle ryanodine receptor was used to raise monoclonal antibodies; epitope mapping demonstrates that monoclonal antibody 419 (mAb419) reacts with a sequence a few residues upstream from Gly341. The mAb419 was then used to probe ryanodine receptor (RYR) functions. Our results show that upon incubation of triads vesicles with mAb419 the Ca2+-induced Ca2+ release rate at pCa 8 was increased. Equilibrium evaluation of [3H]ryanodine binding at different [Ca2+] indicates that mAb419 shifted the half-maximal [Ca2+] for stimulation of ryanodine binding to lower value (0.1 versus 1.2 µM). Such functional effects may be due to a direct action of the Ab on the Ca2+ binding domain of the RYR or to the perturbation by the Ab of the intramolecular interaction between the immunopositive region and regulatory domain of the RYR. The latter hypothesis was tested directly using the optical biosensor BIAcore (Pharmacia Biotech Inc.): we show that the immunopositive RYR polypeptide is able to interact with the native RYR complex. Ligand overlays with immunopositive digoxigenin-RYR fusion protein indicate that such an interaction might occur with a calmodulin binding domain (defined by residues 3010-3225) and with a polypeptide defined by residues 799-1172. In conclusion our results suggest that the stimulation by the mAb419 of the RYR channel activity is due to the perturbation of an intramolecular interaction between the immunopositive polypeptide and a Ca2+ regulatory site probably corresponding to a calmodulin binding domain. A fusion protein encompassing Gly341 of the skeletal muscle ryanodine receptor was used to raise monoclonal antibodies; epitope mapping demonstrates that monoclonal antibody 419 (mAb419) reacts with a sequence a few residues upstream from Gly341. The mAb419 was then used to probe ryanodine receptor (RYR) functions. Our results show that upon incubation of triads vesicles with mAb419 the Ca2+-induced Ca2+ release rate at pCa 8 was increased. Equilibrium evaluation of [3H]ryanodine binding at different [Ca2+] indicates that mAb419 shifted the half-maximal [Ca2+] for stimulation of ryanodine binding to lower value (0.1 versus 1.2 µM). Such functional effects may be due to a direct action of the Ab on the Ca2+ binding domain of the RYR or to the perturbation by the Ab of the intramolecular interaction between the immunopositive region and regulatory domain of the RYR. The latter hypothesis was tested directly using the optical biosensor BIAcore (Pharmacia Biotech Inc.): we show that the immunopositive RYR polypeptide is able to interact with the native RYR complex. Ligand overlays with immunopositive digoxigenin-RYR fusion protein indicate that such an interaction might occur with a calmodulin binding domain (defined by residues 3010-3225) and with a polypeptide defined by residues 799-1172. In conclusion our results suggest that the stimulation by the mAb419 of the RYR channel activity is due to the perturbation of an intramolecular interaction between the immunopositive polypeptide and a Ca2+ regulatory site probably corresponding to a calmodulin binding domain.
proteins
2025-08-21 | RyR1-mediated Ca2+-induced Ca2+ release plays a negligible role in excitation-contraction coupling of normal skeletal muscle.
Type 1 ryanodine receptor (RyR1) is a Ca2+ release channel in the sarcoplasmic reticulum in skeletal muscle. In excitation-contraction (E-C) coupling, RyR1 opens by depolarization of transverse tubule membrane via physical interaction with dihydropyridine receptor, which is referred to as depolarization-induced Ca2+ release (DICR). RyR1 can also be gated via Ca2+-induced Ca2+ release (CICR), in which binding of Ca2+ directly opens the channel. Thus, RyR1 has two Ca2+ release modes; DICR and CICR, but the physiological role of CICR has been a matter of debate: whether CICR can amplify Ca2+ signals in E-C coupling. To address this issue, we created a mouse model carrying a mutation in the Ca2+-binding site in RyR1 (RyR1-E3896A), which selectively inhibits CICR. Surprisingly, the homozygous RyR1-E3896A mice show no appreciable changes in E-C coupling, ex vivo muscle contraction, in vivo muscle performance, or muscle fiber type. Gain-of-function mutations in RyR1 cause malignant hyperthermia (MH), which is a lethal disease triggered by inhalational anesthetics. The E3896A mutation conferred resistance to isoflurane-induced MH episodes and severe heat stroke triggered by environmental heat stress. Our data suggest that RyR1-mediated CICR plays a negligible role in E-C coupling of normal skeletal muscle but may increase the risk for muscle diseases when excessively activated.
2024-01-26 | Disorders of Intermediaries of Metabolism and Malignant Hyperthermia
Many inherited conditions result from disorders of intermediary metabolism. Many more are discovered annually using advanced gene sequencing and other tools. These diseases cause symptoms because of the accumulation of precursors, absence of the final product, excessive toxic intermediaries, or a combination of all three mechanisms. Many are fatal in childhood, but some are compatible with adult life and pregnancy. A better understanding of the enzymatic deficiencies and new technologies have made recombinant enzyme replacement therapy possible. Along with early diet manipulation, current management allows many patients to live relatively normal lives. Because fertility may not be affected, some of these conditions will be encountered by the anesthesiologist. This chapter describes diseases caused by certain enzyme deficiencies and the by-products that cause symptoms. Some are exacerbated by pregnancy and the stress of labor and delivery. The anesthesiologist plays an essential role in reducing physiologic stress and avoiding triggering agents and routines that cause severe metabolic derangements or cardiopulmonary decompensation. The final portion of the chapter describes the most recent advances in the prevention and treatment of malignant hyperthermia in pregnancy, discussing the impact on mother and baby.
2023-02-08 | Muscle calcium stress cleaves junctophilin1, unleashing a gene regulatory program predicted to correct glucose dysregulation.
Calcium ion movements between cellular stores and the cytosol govern muscle contraction, the most energy-consuming function in mammals, which confers skeletal myofibers a pivotal role in glycemia regulation. Chronic myoplasmic calcium elevation ("calcium stress"), found in malignant hyperthermia-susceptible (MHS) patients and multiple myopathies, has been suggested to underlie the progression from hyperglycemia to insulin resistance. What drives such progression remains elusive. We find that muscle cells derived from MHS patients have increased content of an activated fragment of GSK3β - a specialized kinase that inhibits glycogen synthase, impairing glucose utilization and delineating a path to hyperglycemia. We also find decreased content of junctophilin1, an essential structural protein that colocalizes in the couplon with the voltage-sensing CaV1.1, the calcium channel RyR1 and calpain1, accompanied by an increase in a 44 kDa junctophilin1 fragment (JPh44) that moves into nuclei. We trace these changes to activated proteolysis by calpain1, secondary to increased myoplasmic calcium. We demonstrate that a JPh44-like construct induces transcriptional changes predictive of increased glucose utilization in myoblasts, including less transcription and translation of GSK3β and decreased transcription of proteins that reduce utilization of glucose. These effects reveal a stress-adaptive response, mediated by the novel regulator of transcription JPh44.
2021-02-17 | Pathological conformations of disease mutant Ryanodine Receptors revealed by cryo-EM.
Ryanodine Receptors (RyRs) are massive channels that release Ca2+ from the endoplasmic and sarcoplasmic reticulum. Hundreds of mutations are linked to malignant hyperthermia (MH), myopathies, and arrhythmias. Here, we explore the first MH mutation identified in humans by providing cryo-EM snapshots of the pig homolog, R615C, showing that it affects an interface between three solenoid regions. We also show the impact of apo-calmodulin (apoCaM) and how it can induce opening by bending of the bridging solenoid, mediated by its N-terminal lobe. For R615C RyR1, apoCaM binding abolishes a pathological 'intermediate' conformation, distributing the population to a mixture of open and closed channels, both different from the structure without apoCaM. Comparisons show that the mutation primarily affects the closed state, inducing partial movements linked to channel activation. This shows that disease mutations can cause distinct pathological conformations of the RyR and facilitate channel opening by disrupting interactions between different solenoid regions.
2020-12-10 | Molecular Modification of Transient Receptor Potential Canonical 6 Channels Modulates Calcium Dyshomeostasis in a Mouse Model Relevant to Malignant Hyperthermia
Background Pharmacologic modulation has previously shown that transient receptor potential canonical (TRPC) channels play an important role in the pathogenesis of malignant hyperthermia. This study tested the hypothesis that genetically suppressing the function of TRPC6 can partially ameliorate muscle cation dyshomeostasis and the response to halothane in a mouse model relevant to malignant hyperthermia. Methods This study examined the effect of overexpressing a muscle-specific nonconducting dominant-negative TRPC6 channel in 20 RYR1-p.R163C and 20 wild-type mice and an equal number of nonexpressing controls, using calcium- and sodium-selective microelectrodes and Western blots. Results RYR1-p.R163C mouse muscles have chronically elevated intracellular calcium and sodium levels compared to wild-type muscles. Transgenic expression of the nonconducting TRPC6 channel reduced intracellular calcium from 331 ± 34 nM (mean ± SD) to 190 ± 27 nM (P < 0.0001) and sodium from 15 ± 1 mM to 11 ± 1 mM (P < 0.0001). Its expression lowered the increase in intracellular Ca2+ of the TRPC6-specific activator hyperforin in RYR1-p.R163C muscle fibers from 52% (348 ± 37 nM to 537 ± 70 nM) to 14% (185 ± 11 nM to 210 ± 44 nM). Western blot analysis of TRPC3 and TRPC6 expression showed the expected increase in TRPC6 caused by overexpression of its dominant-negative transgene and a compensatory increase in expression of TRPC3. Although expression of the muscle-specific dominant-negative TRPC6 was able to modulate the increase in intracellular calcium during halothane exposure and prolonged life (35 ± 5 min vs. 15 ± 3 min; P < 0.0001), a slow, steady increase in calcium began after 20 min of halothane exposure, which eventually led to death. Conclusions These data support previous findings that TRPC channels play an important role in causing the intracellular calcium and sodium dyshomeostasis associated with RYR1 variants that are pathogenic for malignant hyperthermia. However, they also show that modulating TRPC channels alone is not sufficient to prevent the lethal effect of exposure to volatile anesthetic malignant hyperthermia–triggering agents. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New
other
2023-01-26 | The potential value of exosomes as adjuvants for novel biologic local anesthetics
The side effects of anesthetic drugs are a key preoperative concern for anesthesiologists. Anesthetic drugs used for general anesthesia and regional blocks are associated with a potential risk of systemic toxicity. This prompted the use of anesthetic adjuvants to ameliorate these side effects and improve clinical outcomes. However, the adverse effects of anesthetic adjuvants, such as neurotoxicity and gastrointestinal reactions, have raised concerns about their clinical use. Therefore, the development of relatively safe anesthetic adjuvants with fewer side effects is an important area for future anesthetic drug research. Exosomes, which contain multiple vesicles with genetic information, can be released by living cells with regenerative and specific effects. Exosomes released by specific cell types have been found to have similar effects as many local anesthetic adjuvants. Due to their biological activity, carrier efficacy, and ability to repair damaged tissues, exosomes may have a better efficacy and safety profile than the currently used anesthetic adjuvants. In this article, we summarize the contemporary literature about local anesthetic adjuvants and highlight their potential side effects, while discussing the potential of exosomes as novel local anesthetic adjuvant drugs.
2021-10-25 | The Use of Continuous Blood Purification for the Treatment of Malignant Hyperthermia in an Infant.
Malignant hyperthermia (MH) is a rare and potentially life-threatening pharmacogenetic disorder encountered during general anesthesia, with the incidence higher in children than in adults. Dantrolene is the specific antagonist of MH, but it is not readily available in China, thus developing alternative treatment protocols is of great practical importance. Herein, the authors report a two-month-old infant who underwent holmium laser epiglottis retrofitting through a bronchoscope, but developed limb muscular stiffness, tachypnea, tachycardia, and hyperthermia after sevoflurane exposure. After the diagnosis of MH, corresponding supportive treatment was implemented. Because there was no dantrolene available, continuous blood purification and mechanical ventilation were performed. A few days later, the boy recovered without any complications. Based on the authors' successful clinical practice, the authors consider continuous blood purification as a reliable treatment for MH. But its feasibility still needs to be clarified after multicenter clinical observations.
2018-05-01 | Towards the immortalisation of primary human myoblasts derived from patients susceptible to malignant hyperthermia and their non-susceptible relatives
Malignant hyperthermia (MH) is a pharmacogenetic condition whereby in susceptible individuals, a rapid hypermetabolic response results from skeletal muscle calcium dysregulation 1. Current studies into MH are limited by the utility of non-human skeletal muscle models or human non-skeletal muscle cell lines such as HEK-293 cells 2,3. Furthermore, experiments that use primary human tissue are inherently limited because of the rapid onset of replicative senescence that has been observed 4. Thus, there is a crucial need to develop methods that will extend the life of cells derived from patients who are susceptible to MH (MHS) and their non-susceptible relatives (MHN) in order to allow an improved understanding of the mechanisms that underlie the pathophysiology of the human MH reaction. This study aims to develop such human skeletal muscle cell lines derived from patients with unique mutations associated with MH as well as those from their MHN relatives. Human biopsy samples taken for the diagnostic in vitro contracture tests were processed as previously described to isolate human myoblasts 5. Myoblasts from three MHS patients, three MHN family members and a non-related MHN individual, were infected using the γ-retroviral system to deliver genes encoding CDK-4 (cyclin dependent kinase) and hTERT (human telomerase reverse transcriptase). Successfully infected cells were selected using both puromycin (0.3 μg/ml) and hygromycin (50 μg/ml) for at least two weeks. Cells were then allowed to proliferate to over 10 doublings before undergoing fluorescent activated cell sorting (FACS) for CD56 and CD82 antigens in order to produce monoclonal and polyclonal pure myoblast cell lines. Myoblasts from two MHS patients and four MHN patients survived dual antibiotic selection for at least two weeks. These cells proliferated from approximately 10 000 cells to over one million cells prior to undergoing FACS, following which they were clonally expanded. All immortalised samples were found to contain cells positive for both CD56 and CD82, a combination which has recently been reported to be a marker of myoblasts that are able to differentiate into myotubes 6. The immortalisation of these six primary human samples from MHS and MHN patients is novel the best of our knowledge. The cells are currently undergoing further characterisation in order to produce a regenerative pool of cells that will have the ability to replicate by more than 100 doublings and potentially providing over 1 × 1030 cells per sample 4. This will yield sufficient human cells derived from MHS and MHN patients that can then be used for numerous detailed studies investigating the fundamental mechanisms involved in MH. 1.Hopkins PM., British Journal of Anaesthesia . 2011; 107: 48–56.2.Bannister RA, Estaeve E, Eltit JM, et al. The Journal of General Physiology. 2010; 135: 629–40.3.Murayama T, Kurebayashi N, Ogawa N, et al. Human Mutation. 2016; 37: 1231–41.4.Mamchaoui K, Trollet C, Bigot A, et al. Skeletal Muscle. 2011; 1: 31.5.Rando TA, Blau HM. Journal of Cell Biology. 1994; 125: 1275–87.6.Alexander MS, Rozkalne A, Colletta A, et al. Cell Stem Cell. 2016; 19: 800–07.
2014-06-24 | Oligonol Supplementation Affects Leukocyte and Immune Cell Counts after Heat Loading in Humans
Oligonol is a low-molecular-weight form of polyphenol and has antioxidant and anti-inflammatory activity, making it a potential promoter of immunity. This study investigates the effects of oligonol supplementation on leukocyte and immune cell counts after heat loading in 19 healthy male volunteers. The participants took a daily dose of 200 mg oligonol or a placebo for 1 week. After a 2-week washout period, the subjects were switched to the other study arm. After each supplement, half-body immersion into hot water was made, and blood was collected. Then, complete and differential blood counts were performed. Flow cytometry was used to enumerate and phenotype lymphocyte subsets. Serum concentrations of interleukin (IL)-1β and IL-6 in blood samples were analyzed. Lymphocyte subpopulation variables included counts of total T cells, B cells, and natural killer (NK) cells. Oligonol intake attenuated elevations in IL-1β (an 11.1-fold change vs. a 13.9-fold change immediately after heating; a 12.0-fold change vs. a 12.6-fold change 1h after heating) and IL-6 (an 8.6-fold change vs. a 9.9-fold change immediately after heating; a 9.1-fold change vs. a 10.5-fold change 1h after heating) immediately and 1 h after heating in comparison to those in the placebo group. Oligonol supplementation led to significantly higher numbers of leukocytes (a 30.0% change vs. a 21.5% change immediately after heating; a 13.5% change vs. a 3.5% change 1h after heating) and lymphocytes (a 47.3% change vs. a 39.3% change immediately after heating; a 19.08% change vs. a 2.1% change 1h after heating) relative to those in the placebo group. Oligonol intake led to larger increases in T cells, B cells, and NK cells at rest (p < 0.05, p < 0.05, and p < 0.001, respectively) and immediately after heating (p < 0.001) in comparison to those in the placebo group. In addition, levels of T cells (p < 0.001) and B cells (p < 0.001) were significantly higher 1 h after heating in comparison to those in the placebo group. These results demonstrate that supplementation with oligonol for 1 week may enhance the immune function under heat and suggest a potential useful adjunct to chemotherapy in malignant diseases.
small molecules
2026-07-28 | Cooperative roles of W882 and W996 in state-dependent dantrolene stabilization within the RyR1 P1 domain.
Dantrolene is a clinically approved therapeutic used to suppress abnormal calcium release associated with malignant hyperthermia linked to RyR1 mutations. Cryo-electron microscopy studies have revealed a putative dantrolene-binding cavity within the RyR1 P1 domain and highlighted several residues associated with ligand recognition. However, the dynamic molecular interactions governing ligand stabilization within this region remain incompletely understood. MM/GBSA calculations, conformational entropy analyses, and potential of mean force (PMF) profiling were employed to investigate the local binding dynamics of dantrolene within isolated RyR1 P1-domain complexes. Comparative analyses of the P1 domain from open- and closed-state conformations of RyR1 revealed that the closed-state complex provides a more stable binding environment characterized by lower backbone fluctuations, enhanced ligand-protein contacts, stabilization of a distal loop region (residues 1006-1028), and higher ligand dissociation barriers. Per-residue energetic decomposition and interaction analyses identified W882 and W996 as major contributors to ligand stabilization through cooperative hydrogen bonding and π-mediated interactions. Alanine substitution of these residues increased ligand conformational flexibility and substantially reduced the energetic barriers associated with ligand dissociation, whereas R1000 exhibited comparatively smaller contributions to overall binding stability. Overall, these computational findings are consistent with previous experimental observations and provide atomistic insight into the interaction networks and structural determinants underlying state-dependent stabilization of dantrolene in a cryo-EM-derived RyR1 P1-domain binding model.
2026-05-31 | Anesthesia Management in a Patient With a History of Fulminant Malignant Hyperthermia and a Homozygous RYR1 p.Arg530His Variant Undergoing Laparoscopic Surgery: A Case Report.
BACKGROUND Malignant hyperthermia (MH) is a rare but potentially fatal pharmacogenetic disorder triggered by volatile anesthetics or suxamethonium, most commonly associated with variants in the ryanodine receptor type 1 (RYR1) gene. Patients with confirmed or suspected MH susceptibility are advised to avoid triggering agents and undergo regional anesthesia or total intravenous anesthesia (TIVA). Remimazolam, an ultra-short-acting benzodiazepine approved in Japan for general anesthesia, has been shown in vitro not to increase intracellular calcium concentrations in cells expressing MH-associated RYR1 variants. However, clinical evidence regarding its safety in genetically confirmed MH remains limited. CASE REPORT An 80-year-old man with a history of fulminant MH at age 39, successfully treated with dantrolene, was scheduled for laparoscopic inguinal hernia repair. Previous calcium-induced calcium release testing confirmed MH susceptibility. Genetic analysis revealed homozygosity for the RYR1 c.1589G>A (p.Arg530His) variant, classified as likely pathogenic. Given his history and cardiovascular comorbidities, remimazolam-based TIVA was selected. Anesthesia was induced and maintained with remimazolam, remifentanil, and rocuronium under strict MH precautions, including immediate availability of dantrolene. Intraoperative end-tidal carbon dioxide, core temperature, and hemodynamics remained stable, with no signs of MH. Neuromuscular blockade was reversed with sugammadex, and recovery was uneventful without postoperative complications. CONCLUSIONS Remimazolam-based TIVA was successfully administered in a patient with genetically confirmed MH susceptibility carrying a homozygous likely pathogenic RYR1 variant. The perioperative course was uneventful, suggesting that remimazolam-based TIVA may be a feasible anesthetic approach in selected high-risk MH-susceptible patients, including those with severe prior episodes and significant cardiovascular comorbidities.
2026-05-26 | Beyond the first bout: Adaptations to repeated injuries across physiological and pathological conditions.
Skeletal muscle exhibits remarkable plasticity following injury, yet most research has focused on responses to a single bout of eccentric contractions. This review addresses adaptations to repeated eccentric contraction-induced injuries across physiological and pathological conditions, with emphasis on insights from preclinical rodent models. In healthy muscle, the repeated bout effect (RBE) reduces strength loss and accelerates recovery after subsequent bouts. However, these adaptations are highly condition dependent. Aging can attenuate the RBE, while dystrophic muscle remains vulnerable to repeated injury despite compensatory remodeling. Other factors, including but not limited to, chronic alcohol intake and malignant hyperthermia can influence these responses, though their effects vary and do not universally abolish adaptation. Collectively, these findings highlight that the trajectory of muscle adaptation depends on its physiological state and underlying pathology. Understanding these condition-specific mechanisms is essential for developing targeted strategies to optimize recovery, maximize adaptations, and preserve muscle health across diverse populations.
2026-04-11 | Use of total intravenous anesthesia with propofol and a vaporizer-free ventilator to prevent recurrence of malignant hyperthermia in a dog.
Malignant hyperthermia (MH) is a rare, life-threatening perioperative complication most commonly triggered by inhalant anesthetics or depolarizing neuromuscular blocking agents. Genetic variants affecting skeletal muscle are believed to underlie the susceptibility to MH. Although total intravenous anesthesia (TIVA) has been employed in human patients with MH susceptibility as a nontriggering alternative, comparable data and standardized protocols are limited in veterinary medicine. A 13-year-old spayed female Toy Poodle dog with a history of suspected MH during isoflurane anesthesia 4 years earlier, characterized by a rapid increase in body temperature (42.0 °C) and end-tidal carbon dioxide tension (PE´CO2), and successfully treated with active cooling and dantrolene administration, presented for treatment of an asymptomatic tongue mass. General anesthesia was planned to facilitate a thorough oral examination and biopsy. TIVA with propofol was performed to prevent MH recurrence, using a vaporizer-free ventilator. Following anesthetic premedication with buprenorphine (20 μg kg-1, intravenously) and atropine sulfate (25 μg kg-1, subcutaneously), anesthesia was induced with propofol to allow endotracheal intubation and maintained with a propofol variable rate intravenous infusion (0.4-0.5 mg kg-1 minute-1) under mechanical ventilation with 100% oxygen. Dantrolene was available but was not required. During the 37-minute anesthetic period, rectal temperature gradually decreased, and PE´CO2 remained stable. Inspired isoflurane fraction was undetectable during the perioperative period. Recovery was smooth, and postoperative blood tests revealed only mild creatine kinase elevation. Whole-genome sequencing of peripheral blood DNA revealed a missense variant in the ryanodine receptor gene (RYR1), identical to a known human MH-causing mutation (p.Arg2435His). This case suggests that propofol-based TIVA combined with a vaporizer-free ventilator can safely prevent MH recurrence in genetically susceptible dogs, highlighting the importance of eliminating all potential MH triggers in susceptible individuals.
2026-02-06 | Continuous Epidural Anesthesia for Living-related Renal Transplant in a Patient With Malignant Hyperthermia and Reduced Cardiac Function: A Case Report and Narrative Review of the Literature.
Kidney transplantation is most often performed under general anesthesia, with or without regional anesthesia for adjunctive pain control. Select patients may benefit from neuraxial anesthesia as their primary anesthetic, especially when their comorbidities preclude the safe provision of general anesthesia. In this report, we describe the case of a 75-year-old man with malignant hyperthermia and ischemic cardiomyopathy who underwent a living-related kidney transplant under epidural anesthesia. Intraoperative hemodynamics were stable, and pain control was excellent; the surgeon reported no difficulties during the procedure. Allograft function was immediate and robust, and postoperative pain was well-controlled. The patient denied any side effects from the epidural block. We then summarize relevant literature from the 1960s through the present time regarding neuraxial blocks as the primary anesthetic for kidney transplantation and address considerations around the performance of neuraxial anesthesia in patients with end-stage renal disease. We also discuss common hesitations with neuraxial anesthesia and summarize the available data on patient-centered outcomes. Neuraxial anesthesia affords benefits of similar hemodynamics, similar allograft function, and improved postoperative pain control for patients undergoing kidney transplantation, compared to general anesthesia. Spinal, epidural, or combined spinal-epidural techniques should be given consideration when designing an anesthetic for patients with certain comorbidities that heighten the risk of a general anesthetic.
gene therapies
2026-03-30 | Advances in malignant hyperthermia: pathophysiology, diagnosis and management
Malignant hyperthermia (MH) is a rare genetic disorder triggered by volatile anaesthestics and depolarizing muscle relaxants like sevoflurane, desflurane, and succinylcholine. It is mainly associated with pathogenic variants in the RYR1 and CACNA1S genes that disrupt calcium regulation in skeletal muscles, causing uncontrolled calcium release from the sarcoplasmic reticulum and a hypermetabolic crisis with rhabdomyolysis, muscle rigidity, hypercapnia, hyperthermia, and multiorgan failure. Since its first clinical description in the 1960s, clinical signs such as tachycardia, rising end-tidal CO₂ (ETCO₂), and sudden hyperthermia remain essential for detection. Diagnosis relies on invasive muscle contracture tests like the Caffeine-Halothane contracture test (CHCT) and in vitro contracture test (IVCT). Next-generation sequencing (NGS) identifies mutations in RYR1, CACNA1S, and related excitation–contraction coupling genes. Despite incomplete genotype-phenotype correlations, mechanisms including oxidative stress and sodium-calcium channel dysregulation improve understanding of MH susceptibility. Management requires immediate cessation of triggering agents, intravenous dantrolene, and supportive care including cooling, correction of acidosis, electrolyte control, and monitoring of cardiac and renal complications. Patients should be monitored for recurrence within 24 hours and receive genetic counselling, medical alert identification, and family screening due to autosomal dominant inheritance. Emerging research explores CRISPR/Cas9 correction of RYR1 mutations, antisense oligonucleotide therapy to suppress mutant transcripts, and antioxidants N-acetylcysteine and Trolox to reduce reactive oxygen species-mediated muscle injury; animal studies show improved calcium regulation but human trials are needed. Preventive measures include temperature and ETCO₂ monitoring, regional anaesthesia in obstetrics, and total intravenous anaesthesia, when necessary, supported by collaboration among anaesthesiologists, geneticists, intensivists, and surgeons.
2025-07-25 | Calsequestrin-1 Deficiency Induced Malignant Hyperthermia-Like Skeletal Injury through Mitochondrial Disorder.
Calsequestrin-1 (CASQ1) is a candidate gene defect for malignant hyperthermia (MH) with significant skeletal muscle symptoms and injury, in which mitochondrial dysfunction may play an important role. However, the mechanisms underlying the mitochondrial changes are unknown. In this study we aimed to investigate the possible mechanisms for mitochondrial disorder using calseguestrin-1 knockout (Casq1-KO) mice. Casq1-KO mouse skeletal muscle injury was detected by the measurement of grip strength, and hematoxylin-eosin (H&E) and Gomori immune-staining. Mitochondrial function was evaluated by assessments of membrane potential (MMP), ATP production, and mitochondrial Ca2+ level. Western blot and malondialdehyde (MDA) assays were used to evaluate mitochondrial oxidative stress. AAV9-carrying CMV-Casq1 gene transfection was applied to confirm the effect of Casq1 deficiency on the skeletal muscle. The results showed that Casq1-KO mice exhibited obvious skeletal muscle dysfunction, structural change, and promotions of reactive oxygen species (ROS) production and its signal pathway activation. Significant decreases in ATP production and MMP, and an increase in mitochondrial Ca2+ level were observed in Casq1-KO skeletal mitochondria compared with those of WT. Interestingly, the expression of mitochondrial Ca2+ channel (MICU1), an important mitochondrial Ca2+ regulatory protein, was remarkably reduced in Casq1-KO skeletal mitochondria. Transduction of AAV9-CMV-Casq1 into Casq1-KO skeletal muscle recovered the Casq1 and MICU1 expression, mitochondrial Ca2+ level, MMP, and ATP production, with significant mitigation of skeletal oxidative stress and injuries. In conclusion, Casq1 deficiency or dysfunction could induce skeletal muscle injuries directly. Depressed MICU1 expression with an increased mitochondrial Ca2+ and ROS production may contribute significantly to the skeletal myopathy in malignant hyperthermia-like skeletal syndrome.
2022-06-13 | Variants in ASPH cause exertional heat illness and are associated with malignant hyperthermia susceptibility
Abstract Exertional heat illness (EHI) and malignant hyperthermia (MH) are life threatening conditions associated with muscle breakdown in the setting of triggering factors including volatile anesthetics, exercise, and high environmental temperature. To identify new genetic variants that predispose to EHI and/or MH, we performed genomic sequencing on a cohort with EHI/MH and/or abnormal caffeine-halothane contracture test. In five individuals, we identified rare, pathogenic heterozygous variants in ASPH , a gene encoding junctin, a regulator of excitation-contraction coupling. We validated the pathogenicity of these variants using orthogonal pre-clinical models, CRISPR-edited C2C12 myotubes and transgenic zebrafish. In total, we demonstrate that ASPH variants represent a new cause of EHI and MH susceptibility.
2019-02-15 | Masseter muscle rigidity and the role of DNA analysis to confirm malignant hyperthermia susceptibility
Malignant hyperthermia (MH) is an uncommon, autosomal dominant disorder of skeletal muscle, triggered by inhalational anaesthetics or depolarizing muscle relaxants. Masseter muscle rigidity (MMR) can be regarded as potentially a preceding sign for an MH reaction. Susceptibility to MH can be determined by the in vitro contracture test (IVCT) or DNA analysis where a familial variant is known. Our aims were to review patients with MMR, where IVCT and DNA analysis had been undertaken, to determine if DNA analysis could be used as an initial screening tool for MH susceptibility, and, by reviewing standard monitored variables (SMVs), to determine if any clinical characteristics could be used to differentiate between MMR patients who are MH susceptible (MHS) and those who are not. Patients with MMR were identified from the Palmerston North Hospital MH Reactions Database. IVCT and DNA analysis results were documented. DNA testing was performed retrospectively in the majority of patients as many patients had presented before DNA analysis was available. Forty-one patients were analysed. Fourteen were DNA positive/IVCT positive and six DNA positive only (48% in total), seven were IVCT positive/DNA negative and 14 were IVCT normal. Increased creatine kinase (>18,000 units/L) was consistent with MH susceptibility. Severity of MMR was not linked to MH susceptibility. This study confirmed that DNA analysis can be used as a first-line test for MH susceptibility in patients presenting with MMR (consistent with European MH Group recommendations). Creatine kinase was the only SMV that was significantly different between MHS and MH normal individuals.
2014-10-16 | Adenovirus-mediated expression of myogenic differentiation factor 1 (MyoD) in equine and human dermal fibroblasts enables their conversion to caffeine-sensitive myotubes.
Several human and animal myopathies, such as malignant hyperthermia (MH), central core disease and equine recurrent exertional rhabdomyolysis (RER) are confirmed or thought to be associated with dysfunction of skeletal muscle calcium regulation. For some patients in whom the genetic cause is unknown, or when mutational analysis reveals genetic variants with unclear pathogenicity, defects are further studied through use of muscle histopathology and in vitro contraction tests, the latter in particular, when assessing responses to ryanodine receptor agonists, such as caffeine. However, since muscle biopsy is not always suitable, researchers have used cultured cells to model these diseases, by examining calcium regulation in myotubes derived from skin, following forced expression of muscle-specific transcription factors. Here we describe a novel adenoviral vector that we used to express equine MyoD in dermal fibroblasts. In permissive conditions, transduced equine and human fibroblasts differentiated into multinucleated myotubes. We demonstrate that these cells have a functional excitation-calcium release mechanism and, similarly to primary muscle-derived myotubes, respond in a dose-dependent manner to increasing concentrations of caffeine. MyoD-induced conversion of equine skin-derived fibroblasts offers an attractive method for evaluating calcium homeostasis defects in vitro without the need for invasive muscle biopsy.
antibodies
2025-11-10 | Ca2+, ROS, IL-6, and p38 MAPK signaling loops underlying alterations in myotube formation induced by a severe MH/CCD mutation in RyR1.
Mutations in the gene encoding the skeletal muscle ryanodine receptor (RyR1) can result in muscle diseases, termed RyR1-related myopathies (RyR1-RM). Examples include malignant hyperthermia (MH), central core disease (CCD), and centronuclear myopathy (CNM). The muscles involved often have more (and mispositioned) nuclei than normal. A subset of the corresponding mutant proteins shows an overactive or leaky sarcoplasmic reticulum (SR) channel behavior that depletes the SR Ca2+ content and increases the level of cytosolic Ca2+. In addition, two remarkable effects of these RyR1 variants have been reported in cultured myogenic cells: enhanced expression of interleukin-6 (IL-6) and stimulation of myoblast fusion (myonuclei accretion). Here, we have investigated whether the latter effect is due to a possible IL-6-dependent autocrine loop. Toward this goal, we analyzed the impact of the overactive Y523S mutant compared with the wild-type RyR1 after expression in C2C12 cells. The results show that this mutation indeed drastically promotes myoblast fusion up to ∼300%. Moreover, this action depends on the sequential activation of SR Ca2+ release, store-operated Ca2+ channels, reactive oxygen species (ROS, cytosolic and mitochondrial), calpain, and calcineurin. In addition, a neutralizing antibody directed against IL-6 and a p38 inhibitor completely suppressed the stimulation of myoblast fusion. Furthermore, in RyR1-expressing cells, myotube formation was promoted by either exogenous IL-6 or conditioned medium obtained from the Y523S-expressing cells. These findings suggest an autocrine mechanism involving the interplay between Ca2+, ROS, IL-6, and p38 signaling pathways in controlling myonuclei density, which could be essential to explain the pathogenesis of RyR1-RM.NEW & NOTEWORTHY Overactive RyR1 mutant proteins are associated with muscle disease; interestingly, they increase the number of myonuclei when expressed in C2C12 cells. We discovered that this alteration depends on a Ca2+/ROS loop, which recruits calpain and calcineurin to stimulate the production of IL-6 and the subsequent autocrine activation of p38. Thus, disease-causing RyR1 mutations require an IL-6 autocrine system to alter myonuclear density. This novel mechanism could be critical to understanding the pathogenesis of congenital myopathies.
2010-06-22 | Store-operated Ca2+ Entry in Malignant Hyperthermia-susceptible Human Skeletal Muscle
In malignant hyperthermia (MH), mutations in RyR1 underlie direct activation of the channel by volatile anesthetics, leading to muscle contracture and a life-threatening increase in core body temperature. The aim of the present study was to establish whether the associated depletion of sarcoplasmic reticulum (SR) Ca2+ triggers sarcolemmal Ca2+ influx via store-operated Ca2+ entry (SOCE). Samples of vastus medialis muscle were obtained from patients undergoing assessment for MH susceptibility using the in vitro contracture test. Single fibers were mechanically skinned, and confocal microscopy was used to detect changes in [Ca2+] either within the resealed t-system ([Ca2+]t-sys) or within the cytosol. In normal fibers, halothane (0.5 mm) failed to initiate SR Ca2+ release or Ca2+t-sys depletion. However, in MH-susceptible (MHS) fibers, halothane induced both SR Ca2+ release and Ca2+t-sys depletion, consistent with SOCE. In some MHS fibers, halothane-induced SR Ca2+ release took the form of a propagated wave, which was temporally coupled to a wave of Ca2+t-sys depletion. SOCE was potently inhibited by "extracellular" application of a STIM1 antibody trapped within the t-system but not when the antibody was denatured by heating. In conclusion, (i) in human MHS muscle, SR Ca2+ depletion induced by a level of volatile anesthetic within the clinical range is sufficient to induce SOCE, which is tightly coupled to SR Ca2+ release; (ii) sarcolemmal STIM1 has an important role in regulating SOCE; and (iii) sustained SOCE from an effectively infinite extracellular Ca2+ pool may contribute to the maintained rise in cytosolic [Ca2+] that underlies MH. In malignant hyperthermia (MH), mutations in RyR1 underlie direct activation of the channel by volatile anesthetics, leading to muscle contracture and a life-threatening increase in core body temperature. The aim of the present study was to establish whether the associated depletion of sarcoplasmic reticulum (SR) Ca2+ triggers sarcolemmal Ca2+ influx via store-operated Ca2+ entry (SOCE). Samples of vastus medialis muscle were obtained from patients undergoing assessment for MH susceptibility using the in vitro contracture test. Single fibers were mechanically skinned, and confocal microscopy was used to detect changes in [Ca2+] either within the resealed t-system ([Ca2+]t-sys) or within the cytosol. In normal fibers, halothane (0.5 mm) failed to initiate SR Ca2+ release or Ca2+t-sys depletion. However, in MH-susceptible (MHS) fibers, halothane induced both SR Ca2+ release and Ca2+t-sys depletion, consistent with SOCE. In some MHS fibers, halothane-induced SR Ca2+ release took the form of a propagated wave, which was temporally coupled to a wave of Ca2+t-sys depletion. SOCE was potently inhibited by "extracellular" application of a STIM1 antibody trapped within the t-system but not when the antibody was denatured by heating. In conclusion, (i) in human MHS muscle, SR Ca2+ depletion induced by a level of volatile anesthetic within the clinical range is sufficient to induce SOCE, which is tightly coupled to SR Ca2+ release; (ii) sarcolemmal STIM1 has an important role in regulating SOCE; and (iii) sustained SOCE from an effectively infinite extracellular Ca2+ pool may contribute to the maintained rise in cytosolic [Ca2+] that underlies MH.
1996-09-01 | Role of Malignant Hyperthermia Domain in the Regulation of Ca2+ Release Channel (Ryanodine Receptor) of Skeletal Muscle Sarcoplasmic Reticulum
A fusion protein encompassing Gly341 of the skeletal muscle ryanodine receptor was used to raise monoclonal antibodies; epitope mapping demonstrates that monoclonal antibody 419 (mAb419) reacts with a sequence a few residues upstream from Gly341. The mAb419 was then used to probe ryanodine receptor (RYR) functions. Our results show that upon incubation of triads vesicles with mAb419 the Ca2+-induced Ca2+ release rate at pCa 8 was increased. Equilibrium evaluation of [3H]ryanodine binding at different [Ca2+] indicates that mAb419 shifted the half-maximal [Ca2+] for stimulation of ryanodine binding to lower value (0.1 versus 1.2 µM). Such functional effects may be due to a direct action of the Ab on the Ca2+ binding domain of the RYR or to the perturbation by the Ab of the intramolecular interaction between the immunopositive region and regulatory domain of the RYR. The latter hypothesis was tested directly using the optical biosensor BIAcore (Pharmacia Biotech Inc.): we show that the immunopositive RYR polypeptide is able to interact with the native RYR complex. Ligand overlays with immunopositive digoxigenin-RYR fusion protein indicate that such an interaction might occur with a calmodulin binding domain (defined by residues 3010-3225) and with a polypeptide defined by residues 799-1172. In conclusion our results suggest that the stimulation by the mAb419 of the RYR channel activity is due to the perturbation of an intramolecular interaction between the immunopositive polypeptide and a Ca2+ regulatory site probably corresponding to a calmodulin binding domain. A fusion protein encompassing Gly341 of the skeletal muscle ryanodine receptor was used to raise monoclonal antibodies; epitope mapping demonstrates that monoclonal antibody 419 (mAb419) reacts with a sequence a few residues upstream from Gly341. The mAb419 was then used to probe ryanodine receptor (RYR) functions. Our results show that upon incubation of triads vesicles with mAb419 the Ca2+-induced Ca2+ release rate at pCa 8 was increased. Equilibrium evaluation of [3H]ryanodine binding at different [Ca2+] indicates that mAb419 shifted the half-maximal [Ca2+] for stimulation of ryanodine binding to lower value (0.1 versus 1.2 µM). Such functional effects may be due to a direct action of the Ab on the Ca2+ binding domain of the RYR or to the perturbation by the Ab of the intramolecular interaction between the immunopositive region and regulatory domain of the RYR. The latter hypothesis was tested directly using the optical biosensor BIAcore (Pharmacia Biotech Inc.): we show that the immunopositive RYR polypeptide is able to interact with the native RYR complex. Ligand overlays with immunopositive digoxigenin-RYR fusion protein indicate that such an interaction might occur with a calmodulin binding domain (defined by residues 3010-3225) and with a polypeptide defined by residues 799-1172. In conclusion our results suggest that the stimulation by the mAb419 of the RYR channel activity is due to the perturbation of an intramolecular interaction between the immunopositive polypeptide and a Ca2+ regulatory site probably corresponding to a calmodulin binding domain.
proteins
2025-08-21 | RyR1-mediated Ca2+-induced Ca2+ release plays a negligible role in excitation-contraction coupling of normal skeletal muscle.
Type 1 ryanodine receptor (RyR1) is a Ca2+ release channel in the sarcoplasmic reticulum in skeletal muscle. In excitation-contraction (E-C) coupling, RyR1 opens by depolarization of transverse tubule membrane via physical interaction with dihydropyridine receptor, which is referred to as depolarization-induced Ca2+ release (DICR). RyR1 can also be gated via Ca2+-induced Ca2+ release (CICR), in which binding of Ca2+ directly opens the channel. Thus, RyR1 has two Ca2+ release modes; DICR and CICR, but the physiological role of CICR has been a matter of debate: whether CICR can amplify Ca2+ signals in E-C coupling. To address this issue, we created a mouse model carrying a mutation in the Ca2+-binding site in RyR1 (RyR1-E3896A), which selectively inhibits CICR. Surprisingly, the homozygous RyR1-E3896A mice show no appreciable changes in E-C coupling, ex vivo muscle contraction, in vivo muscle performance, or muscle fiber type. Gain-of-function mutations in RyR1 cause malignant hyperthermia (MH), which is a lethal disease triggered by inhalational anesthetics. The E3896A mutation conferred resistance to isoflurane-induced MH episodes and severe heat stroke triggered by environmental heat stress. Our data suggest that RyR1-mediated CICR plays a negligible role in E-C coupling of normal skeletal muscle but may increase the risk for muscle diseases when excessively activated.
2024-01-26 | Disorders of Intermediaries of Metabolism and Malignant Hyperthermia
Many inherited conditions result from disorders of intermediary metabolism. Many more are discovered annually using advanced gene sequencing and other tools. These diseases cause symptoms because of the accumulation of precursors, absence of the final product, excessive toxic intermediaries, or a combination of all three mechanisms. Many are fatal in childhood, but some are compatible with adult life and pregnancy. A better understanding of the enzymatic deficiencies and new technologies have made recombinant enzyme replacement therapy possible. Along with early diet manipulation, current management allows many patients to live relatively normal lives. Because fertility may not be affected, some of these conditions will be encountered by the anesthesiologist. This chapter describes diseases caused by certain enzyme deficiencies and the by-products that cause symptoms. Some are exacerbated by pregnancy and the stress of labor and delivery. The anesthesiologist plays an essential role in reducing physiologic stress and avoiding triggering agents and routines that cause severe metabolic derangements or cardiopulmonary decompensation. The final portion of the chapter describes the most recent advances in the prevention and treatment of malignant hyperthermia in pregnancy, discussing the impact on mother and baby.
2023-02-08 | Muscle calcium stress cleaves junctophilin1, unleashing a gene regulatory program predicted to correct glucose dysregulation.
Calcium ion movements between cellular stores and the cytosol govern muscle contraction, the most energy-consuming function in mammals, which confers skeletal myofibers a pivotal role in glycemia regulation. Chronic myoplasmic calcium elevation ("calcium stress"), found in malignant hyperthermia-susceptible (MHS) patients and multiple myopathies, has been suggested to underlie the progression from hyperglycemia to insulin resistance. What drives such progression remains elusive. We find that muscle cells derived from MHS patients have increased content of an activated fragment of GSK3β - a specialized kinase that inhibits glycogen synthase, impairing glucose utilization and delineating a path to hyperglycemia. We also find decreased content of junctophilin1, an essential structural protein that colocalizes in the couplon with the voltage-sensing CaV1.1, the calcium channel RyR1 and calpain1, accompanied by an increase in a 44 kDa junctophilin1 fragment (JPh44) that moves into nuclei. We trace these changes to activated proteolysis by calpain1, secondary to increased myoplasmic calcium. We demonstrate that a JPh44-like construct induces transcriptional changes predictive of increased glucose utilization in myoblasts, including less transcription and translation of GSK3β and decreased transcription of proteins that reduce utilization of glucose. These effects reveal a stress-adaptive response, mediated by the novel regulator of transcription JPh44.
2021-02-17 | Pathological conformations of disease mutant Ryanodine Receptors revealed by cryo-EM.
Ryanodine Receptors (RyRs) are massive channels that release Ca2+ from the endoplasmic and sarcoplasmic reticulum. Hundreds of mutations are linked to malignant hyperthermia (MH), myopathies, and arrhythmias. Here, we explore the first MH mutation identified in humans by providing cryo-EM snapshots of the pig homolog, R615C, showing that it affects an interface between three solenoid regions. We also show the impact of apo-calmodulin (apoCaM) and how it can induce opening by bending of the bridging solenoid, mediated by its N-terminal lobe. For R615C RyR1, apoCaM binding abolishes a pathological 'intermediate' conformation, distributing the population to a mixture of open and closed channels, both different from the structure without apoCaM. Comparisons show that the mutation primarily affects the closed state, inducing partial movements linked to channel activation. This shows that disease mutations can cause distinct pathological conformations of the RyR and facilitate channel opening by disrupting interactions between different solenoid regions.
2020-12-10 | Molecular Modification of Transient Receptor Potential Canonical 6 Channels Modulates Calcium Dyshomeostasis in a Mouse Model Relevant to Malignant Hyperthermia
Background Pharmacologic modulation has previously shown that transient receptor potential canonical (TRPC) channels play an important role in the pathogenesis of malignant hyperthermia. This study tested the hypothesis that genetically suppressing the function of TRPC6 can partially ameliorate muscle cation dyshomeostasis and the response to halothane in a mouse model relevant to malignant hyperthermia. Methods This study examined the effect of overexpressing a muscle-specific nonconducting dominant-negative TRPC6 channel in 20 RYR1-p.R163C and 20 wild-type mice and an equal number of nonexpressing controls, using calcium- and sodium-selective microelectrodes and Western blots. Results RYR1-p.R163C mouse muscles have chronically elevated intracellular calcium and sodium levels compared to wild-type muscles. Transgenic expression of the nonconducting TRPC6 channel reduced intracellular calcium from 331 ± 34 nM (mean ± SD) to 190 ± 27 nM (P < 0.0001) and sodium from 15 ± 1 mM to 11 ± 1 mM (P < 0.0001). Its expression lowered the increase in intracellular Ca2+ of the TRPC6-specific activator hyperforin in RYR1-p.R163C muscle fibers from 52% (348 ± 37 nM to 537 ± 70 nM) to 14% (185 ± 11 nM to 210 ± 44 nM). Western blot analysis of TRPC3 and TRPC6 expression showed the expected increase in TRPC6 caused by overexpression of its dominant-negative transgene and a compensatory increase in expression of TRPC3. Although expression of the muscle-specific dominant-negative TRPC6 was able to modulate the increase in intracellular calcium during halothane exposure and prolonged life (35 ± 5 min vs. 15 ± 3 min; P < 0.0001), a slow, steady increase in calcium began after 20 min of halothane exposure, which eventually led to death. Conclusions These data support previous findings that TRPC channels play an important role in causing the intracellular calcium and sodium dyshomeostasis associated with RYR1 variants that are pathogenic for malignant hyperthermia. However, they also show that modulating TRPC channels alone is not sufficient to prevent the lethal effect of exposure to volatile anesthetic malignant hyperthermia–triggering agents. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New
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2023-01-26 | The potential value of exosomes as adjuvants for novel biologic local anesthetics
The side effects of anesthetic drugs are a key preoperative concern for anesthesiologists. Anesthetic drugs used for general anesthesia and regional blocks are associated with a potential risk of systemic toxicity. This prompted the use of anesthetic adjuvants to ameliorate these side effects and improve clinical outcomes. However, the adverse effects of anesthetic adjuvants, such as neurotoxicity and gastrointestinal reactions, have raised concerns about their clinical use. Therefore, the development of relatively safe anesthetic adjuvants with fewer side effects is an important area for future anesthetic drug research. Exosomes, which contain multiple vesicles with genetic information, can be released by living cells with regenerative and specific effects. Exosomes released by specific cell types have been found to have similar effects as many local anesthetic adjuvants. Due to their biological activity, carrier efficacy, and ability to repair damaged tissues, exosomes may have a better efficacy and safety profile than the currently used anesthetic adjuvants. In this article, we summarize the contemporary literature about local anesthetic adjuvants and highlight their potential side effects, while discussing the potential of exosomes as novel local anesthetic adjuvant drugs.
2021-10-25 | The Use of Continuous Blood Purification for the Treatment of Malignant Hyperthermia in an Infant.
Malignant hyperthermia (MH) is a rare and potentially life-threatening pharmacogenetic disorder encountered during general anesthesia, with the incidence higher in children than in adults. Dantrolene is the specific antagonist of MH, but it is not readily available in China, thus developing alternative treatment protocols is of great practical importance. Herein, the authors report a two-month-old infant who underwent holmium laser epiglottis retrofitting through a bronchoscope, but developed limb muscular stiffness, tachypnea, tachycardia, and hyperthermia after sevoflurane exposure. After the diagnosis of MH, corresponding supportive treatment was implemented. Because there was no dantrolene available, continuous blood purification and mechanical ventilation were performed. A few days later, the boy recovered without any complications. Based on the authors' successful clinical practice, the authors consider continuous blood purification as a reliable treatment for MH. But its feasibility still needs to be clarified after multicenter clinical observations.
2018-05-01 | Towards the immortalisation of primary human myoblasts derived from patients susceptible to malignant hyperthermia and their non-susceptible relatives
Malignant hyperthermia (MH) is a pharmacogenetic condition whereby in susceptible individuals, a rapid hypermetabolic response results from skeletal muscle calcium dysregulation 1. Current studies into MH are limited by the utility of non-human skeletal muscle models or human non-skeletal muscle cell lines such as HEK-293 cells 2,3. Furthermore, experiments that use primary human tissue are inherently limited because of the rapid onset of replicative senescence that has been observed 4. Thus, there is a crucial need to develop methods that will extend the life of cells derived from patients who are susceptible to MH (MHS) and their non-susceptible relatives (MHN) in order to allow an improved understanding of the mechanisms that underlie the pathophysiology of the human MH reaction. This study aims to develop such human skeletal muscle cell lines derived from patients with unique mutations associated with MH as well as those from their MHN relatives. Human biopsy samples taken for the diagnostic in vitro contracture tests were processed as previously described to isolate human myoblasts 5. Myoblasts from three MHS patients, three MHN family members and a non-related MHN individual, were infected using the γ-retroviral system to deliver genes encoding CDK-4 (cyclin dependent kinase) and hTERT (human telomerase reverse transcriptase). Successfully infected cells were selected using both puromycin (0.3 μg/ml) and hygromycin (50 μg/ml) for at least two weeks. Cells were then allowed to proliferate to over 10 doublings before undergoing fluorescent activated cell sorting (FACS) for CD56 and CD82 antigens in order to produce monoclonal and polyclonal pure myoblast cell lines. Myoblasts from two MHS patients and four MHN patients survived dual antibiotic selection for at least two weeks. These cells proliferated from approximately 10 000 cells to over one million cells prior to undergoing FACS, following which they were clonally expanded. All immortalised samples were found to contain cells positive for both CD56 and CD82, a combination which has recently been reported to be a marker of myoblasts that are able to differentiate into myotubes 6. The immortalisation of these six primary human samples from MHS and MHN patients is novel the best of our knowledge. The cells are currently undergoing further characterisation in order to produce a regenerative pool of cells that will have the ability to replicate by more than 100 doublings and potentially providing over 1 × 1030 cells per sample 4. This will yield sufficient human cells derived from MHS and MHN patients that can then be used for numerous detailed studies investigating the fundamental mechanisms involved in MH. 1.Hopkins PM., British Journal of Anaesthesia . 2011; 107: 48–56.2.Bannister RA, Estaeve E, Eltit JM, et al. The Journal of General Physiology. 2010; 135: 629–40.3.Murayama T, Kurebayashi N, Ogawa N, et al. Human Mutation. 2016; 37: 1231–41.4.Mamchaoui K, Trollet C, Bigot A, et al. Skeletal Muscle. 2011; 1: 31.5.Rando TA, Blau HM. Journal of Cell Biology. 1994; 125: 1275–87.6.Alexander MS, Rozkalne A, Colletta A, et al. Cell Stem Cell. 2016; 19: 800–07.
2014-06-24 | Oligonol Supplementation Affects Leukocyte and Immune Cell Counts after Heat Loading in Humans
Oligonol is a low-molecular-weight form of polyphenol and has antioxidant and anti-inflammatory activity, making it a potential promoter of immunity. This study investigates the effects of oligonol supplementation on leukocyte and immune cell counts after heat loading in 19 healthy male volunteers. The participants took a daily dose of 200 mg oligonol or a placebo for 1 week. After a 2-week washout period, the subjects were switched to the other study arm. After each supplement, half-body immersion into hot water was made, and blood was collected. Then, complete and differential blood counts were performed. Flow cytometry was used to enumerate and phenotype lymphocyte subsets. Serum concentrations of interleukin (IL)-1β and IL-6 in blood samples were analyzed. Lymphocyte subpopulation variables included counts of total T cells, B cells, and natural killer (NK) cells. Oligonol intake attenuated elevations in IL-1β (an 11.1-fold change vs. a 13.9-fold change immediately after heating; a 12.0-fold change vs. a 12.6-fold change 1h after heating) and IL-6 (an 8.6-fold change vs. a 9.9-fold change immediately after heating; a 9.1-fold change vs. a 10.5-fold change 1h after heating) immediately and 1 h after heating in comparison to those in the placebo group. Oligonol supplementation led to significantly higher numbers of leukocytes (a 30.0% change vs. a 21.5% change immediately after heating; a 13.5% change vs. a 3.5% change 1h after heating) and lymphocytes (a 47.3% change vs. a 39.3% change immediately after heating; a 19.08% change vs. a 2.1% change 1h after heating) relative to those in the placebo group. Oligonol intake led to larger increases in T cells, B cells, and NK cells at rest (p < 0.05, p < 0.05, and p < 0.001, respectively) and immediately after heating (p < 0.001) in comparison to those in the placebo group. In addition, levels of T cells (p < 0.001) and B cells (p < 0.001) were significantly higher 1 h after heating in comparison to those in the placebo group. These results demonstrate that supplementation with oligonol for 1 week may enhance the immune function under heat and suggest a potential useful adjunct to chemotherapy in malignant diseases.
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Drug Discovery Landscape
3 orphan drug designations for Malignant hyperthermia of anesthesia, including 1 approved therapy.
3 orphan drug designations for Malignant hyperthermia of anesthesia, including 1 approved therapy.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
Dantrolene sodium, hemiheptahydrate [Agilus] | small molecules | EMA | 2021-05-20 | — | Norgine B.V. |
Dantrolene sodium | small molecules | EMA | 2014-11-19 | — | Maxia Strategies-Europe Limited |
dantrolene sodium suspension for injection [RYANODEX] | small molecules | FDA | 2013-08-16 | 2014-07-22 | Eagle Pharmaceuticals, Inc. |
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