scholarly journals A novel saline-soluble, rapidly-metabolized RyR1 inhibitor rescues volatile anesthesia-induced death and environmental heat stroke in a mouse model relevant to malignant hyperthermia

2020 ◽  
Author(s):  
Toshiko Yamazawa ◽  
Takuya Kobayashi ◽  
Nagomi Kurebayashi ◽  
Masato Konishi ◽  
Satoru Noguchi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Water Solubility ◽  
Heat Stroke ◽  
Release Channel ◽  
Volatile Anesthesia ◽  
Intracellular Ca ◽  
Rapid Clearance

AbstractMutations in the type 1 ryanodine receptor (RyR1), a Ca2+ release channel in skeletal muscle, hyperactivate the channel to cause malignant hyperthermia (MH) and are implicated in severe heat stroke. Dantrolene, the only approved drug for MH, has the disadvantages of having very poor water solubility and long plasma half-life. We show here that a novel RyR1-selective inhibitor, 6,7-(methylenedioxy)-1-octyl-4-quinolone-3-carboxylic acid (Compound 1), effectively rescues MH and heat stroke in several mouse models relevant to MH. Compound 1 reduced resting intracellular Ca2+, inhibited halothane-induced Ca2+ release, suppressed caffeine-induced contracture in skeletal muscle, reduced sarcolemmal cation influx, and prevented or reversed the fulminant MH crisis by isoflurane anesthesia and heat stroke by environmental heat stress. Notably, Compound 1 has great advantages of better water solubility and rapid clearance in vivo over dantrolene. Compound 1 has the potential to be a promising new candidate for effective treatment of patients carrying RyR1 mutations.

scholarly journals A novel RyR1-selective inhibitor prevents and rescues sudden death in mouse models of malignant hyperthermia and heat stroke

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Toshiko Yamazawa ◽  
Takuya Kobayashi ◽  
Nagomi Kurebayashi ◽  
Masato Konishi ◽  
Satoru Noguchi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Mouse Models ◽  
Water Solubility ◽  
Heat Stroke ◽  
Selective Inhibitor ◽  
Release Channel ◽  
Intracellular Ca ◽  
Rapid Clearance

AbstractMutations in the type 1 ryanodine receptor (RyR1), a Ca2+ release channel in skeletal muscle, hyperactivate the channel to cause malignant hyperthermia (MH) and are implicated in severe heat stroke. Dantrolene, the only approved drug for MH, has the disadvantages of having very poor water solubility and long plasma half-life. We show here that an oxolinic acid-derivative RyR1-selective inhibitor, 6,7-(methylenedioxy)-1-octyl-4-quinolone-3-carboxylic acid (Compound 1, Cpd1), effectively prevents and treats MH and heat stroke in several mouse models relevant to MH. Cpd1 reduces resting intracellular Ca2+, inhibits halothane- and isoflurane-induced Ca2+ release, suppresses caffeine-induced contracture in skeletal muscle, reduces sarcolemmal cation influx, and prevents or reverses the fulminant MH crisis induced by isoflurane anesthesia and rescues animals from heat stroke caused by environmental heat stress. Notably, Cpd1 has great advantages of better water solubility and rapid clearance in vivo over dantrolene. Cpd1 has the potential to be a promising candidate for effective treatment of patients carrying RyR1 mutations.

scholarly journals Therapeutic effects of novel type 1 ryanodine receptor inhibitor on malignant hyperthermia

2021 ◽  
Vol 154 (9) ◽  
Author(s):  
Toshiko Yamazawa
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Ryanodine Receptor ◽  
Half Life ◽  
Water Solubility ◽  
Heat Stroke ◽  
Therapeutic Effects ◽  
Ryr1 Gene ◽  
Plasma Half Life

Ca2+-induced Ca2+ release (CICR) is mediated by ryanodine receptors, a Ca2+ release channel in the sarcoplasmic/endoplasmic reticulum (SR/ER), and plays an important role in various tissues. Type 1 ryanodine receptor (RYR1) plays a key role during excitation–contraction coupling of skeletal muscle. Mutations in RYR1 overactivate the channel to cause malignant hyperthermia (MH). MH is a serious complication characterized by skeletal muscle rigidity and elevated body temperature in response to commonly used inhalational anesthetics. Thus far, >300 mutations in the RYR1 gene have been reported in patients with MH. Some heat stroke triggered by exercise or environmental heat stress is also related to MH mutations in the RYR1 gene. The only drug approved for ameliorating the symptoms of MH is dantrolene, which has been first developed in the 1960s as a muscle relaxant. However, dantrolene has several disadvantages for clinical use: poor water solubility, which makes rapid preparation difficult in emergency situations, and long plasma half-life, which causes long-lasting side effects such as muscle weakness. Here, we show that a novel RYR1-selective inhibitor, 6,7-(methylenedioxy)-1-octyl-4-quinolone-3-carboxylic acid (compound 1 [Cpd1]), effectively rescues MH and heat stroke in new mouse model (RYR1-p.R2509C) relevant to MH. Cpd1 has great advantages of higher water solubility and shorter plasma half-life compared with dantrolene. Our data suggest that Cpd1 has the potential to be a promising new candidate for effective treatment of patients carrying RYR1 mutations. Finally, we have recently identified that heat directly activates RYR1, which induces Ca2+ release from intracellular stores. Our results provide direct evidence that heat induces Ca2+ release (HICR) from the SR through the mutants rather than wild type RYR1, causing an immediate rise in the cytosolic Ca2+ concentration.

scholarly journals Increased basal metabolic rate in mice susceptible to malignant hyperthermia and heat stroke

2021 ◽  
Vol 154 (9) ◽  
Author(s):  
Matteo Serano ◽  
Laura Pietrangelo ◽  
Cecilia Paolini ◽  
Flavia A. Guarnier ◽  
Feliciano Protasi
Keyword(s):  
Malignant Hyperthermia ◽  
Heat Stroke ◽  
Gene Encoding ◽  
Release Channel ◽  
Western Blots ◽  
Ec Coupling ◽  
Mitochondrial Volume ◽  
Total Body ◽  
Old Mice

Ryanodine receptor type-1 (RYR1) and Calsequestrin-1 (CASQ1) proteins, located in the sarcoplasmic reticulum (SR), are two of the main players in skeletal excitation–contraction (EC) coupling. Mutations in the human RYR1 gene (encoding for the SR Ca2+ release channel) and ablation in mice of CASQ1 (a SR Ca2+ binding protein) cause hypersensitivity to halogenated anesthetics (malignant hyperthermia [MH] susceptibility) and to heat (heat stroke; HS). As both MH and HS are characterized by excessive cytosolic Ca2+ levels and hypermetabolic responses, we studied the metabolism of 4-mo-old mice from two different lines that are MH/HS susceptible: knock-in mice carrying a human MH mutation (RYR1YS) and CASQ1-knockout (ko) mice. RYR1YS and, to a lesser degree, CASQ1-null mice show an increased volume of oxygen consumption (VO2) and a lower respiratory quotient (RQ) compared with WT mice (indicative of a metabolism that relies more on lipids). This finding is accompanied by a reduction in total body fat mass in both Y522S and CASQ1-null mice (again, compared with WT). In addition, we found that RYR1YS and CASQ1-null mice have an increased food consumption (+26.04% and +25.58% grams/day, respectively) and higher basal core temperature (+0.57°C and +0.54°C, respectively) compared with WT mice. Finally, Western blots and electron microscopy indicated that, in hyperthermic mice, (1) SERCA (used to remove myoplasmic Ca2+) and UCP3 (responsible for a thermogenic process that dissipates mitochondrial H+ gradient) are overexpressed, and (2) mitochondrial volume and percentage of damaged mitochondria are both increased. In conclusion, the MH/HS phenotype in RYR1YS and CASQ1-null mice is associated with an intrinsically increased basal metabolism.

Elevated resting [Ca2+]i in myotubes expressing malignant hyperthermia RyR1 cDNAs is partially restored by modulation of passive calcium leak from the SR

2007 ◽  
Vol 292 (5) ◽  
pp. C1591-C1598 ◽  
Author(s):  
Tianzhong Yang ◽  
Eric Esteve ◽  
Isaac N. Pessah ◽  
Tadeusz F. Molinski ◽  
Paul D. Allen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Malignant Hyperthermia ◽  
Muscle Relaxants ◽  
Wild Type ◽  
Inhalation Anesthetics ◽  
Structural Conformation ◽  
Intracellular Ca ◽  
Percent Decrease

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle triggered in susceptible individuals by inhalation anesthetics and depolarizing skeletal muscle relaxants. This syndrome has been linked to a missense mutation in the type 1 ryanodine receptor (RyR1) in more than 50% of cases studied to date. Using double-barreled Ca2+ microelectrodes in myotubes expressing wild-type RyR1 ( WTRyR1) or RyR1 with one of four common MH mutations ( MHRyR1), we measured resting intracellular Ca2+ concentration ([Ca2+]i). Changes in resting [Ca2+]i produced by several drugs known to modulate the RyR1 channel complex were investigated. We found that myotubes expressing any of the MHRyR1s had a 2.0- to 3.7-fold higher resting [Ca2+]i than those expressing WTRyR1. Exposure of myotubes expressing MHRyR1s to ryanodine (500 μM) or (2,6-dichloro-4-aminophenyl)isopropylamine (FLA 365; 20 μM) had no effects on their resting [Ca2+]i. However, when myotubes were exposed to bastadin 5 alone or to a combination of ryanodine and bastadin 5, the resting [Ca2+]i was significantly reduced ( P < 0.01). Interestingly, the percent decrease in resting [Ca2+]i in myotubes expressing MHRyR1s was significantly greater than that for WTRyR1. From these data, we propose that the high resting myoplasmic [Ca2+]i in MHRyR1 expressing myotubes is due in part to a related structural conformation of MHRyR1s that favors “passive” calcium leak from the sarcoplasmic reticulum.

scholarly journals Functional Calsequestrin-1 Is Expressed in the Heart and Its Deficiency Is Causally Related to Malignant Hyperthermia-Like Arrhythmia

Circulation ◽  
2021 ◽  
Author(s):  
Zhipeng Sun ◽  
Luqi Wang ◽  
Lu Han ◽  
Yue Wang ◽  
Yuan Zhou ◽  
...  
Keyword(s):  
Heart Rate ◽  
Ventricular Tachycardia ◽  
Malignant Hyperthermia ◽  
Ex Vivo ◽  
Heat Stroke ◽  
Time Lapse ◽  
Underlying Mechanism ◽  
Neonatal Rat ◽  
Polymorphic Ventricular Tachycardia

Background: Calsequestrins (Casqs), comprising the Casq1 and Casq2 isoforms, buffer Ca 2+ and regulate its release in the sarcoplasmic reticulum (SR) of skeletal and cardiac muscle, respectively. Human inherited diseases associated with mutations in CASQ1 or CASQ2 include malignant hyperthermia/environmental heat stroke (MH/EHS) and catecholaminergic polymorphic ventricular tachycardia. However, patients with an MH/EHS event often suffer from arrhythmia for which the underlying mechanism remains unknown. Methods: Working hearts from conventional ( Casq1 -KO) and cardiac-specific ( Casq1 -CKO) Casq1 knockout mice were monitored in vivo and ex vivo by electrocardiogram and electrical mapping, respectively. MH was induced by 2% isoflurane and treated intraperitoneally with dantrolene. Time-lapse imaging was used to monitor intracellular Ca 2+ activity in isolated mouse cardiomyocytes or neonatal rat ventricular myocytes (NRVMs) with knockdown, over-expression or truncation of the Casq1 gene. Conformational change in both Casqs was determined by crosslinking Western blot analysis. Results: Like MH/EHS patients, Casq1 -KO and Casq1 -CKO mice had faster basal heart rate, and ventricular tachycardia upon exposure to 2% isoflurane, which could be relieved by dantrolene. Basal sinus tachycardia and ventricular ectopic electrical triggering also occurred in Casq1 -KO hearts ex vivo . Accordingly, the ventricular cardiomyocytes from Casq1 -CKO mice displayed dantrolene-sensitive increased Ca 2+ waves and diastole premature Ca 2+ transients/oscillations upon isoflurane. NRVMs with Casq1-knockdown had enhanced spontaneous Ca2+ sparks/transients upon isoflurane, while cells over-expressing Casq1 exhibited decreased Ca2+ sparks/transients that were absent in cells with truncation of 9 amino acids at the C-terminus of Casq1. Structural evaluation showed that most of the Casq1 protein was present as a polymer and physically interacted with RyR2 in the ventricular SR. The Casq1 isoform was also expressed in human myocardium. Mechanistically, exposure to 2% isoflurane or heating at 41ºC induced Casq1 oligomerization in mouse ventricular and skeletal muscle tissues, leading to a reduced Casq1/RyR2 interaction and increased RyR2 activity in the ventricle. Conclusions: Casq1 is expressed in the heart, where it regulates SR Ca 2+ release and heart rate. Casq1 deficiency independently causes MH/EHS-like ventricular arrhythmia by trigger-induced Casq1 oligomerization and a relief of its inhibitory effect on RyR2-mediated Ca 2+ release, thus revealing a new inherited arrhythmia and a novel mechanism for MH/EHS arrhythmogenesis.

scholarly journals Defective Acetylcholine Receptor Subunit Switch Precedes Atrophy of Slow-Twitch Skeletal Muscle Fibers Lacking ERK1/2 Kinases in Soleus Muscle

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Shuo Wang ◽  
Bonnie Seaberg ◽  
Ximena Paez-Colasante ◽  
Mendell Rimer
Keyword(s):  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Soleus Muscle ◽  
Muscle Fibers ◽  
Neuromuscular Synapse ◽  
Fiber Morphology ◽  
Skeletal Muscle Fibers ◽  
Slow Twitch

Abstract To test the role of extracellular-signal regulated kinases 1 and 2 (ERK1/2) in slow-twitch, type 1 skeletal muscle fibers, we studied the soleus muscle in mice genetically deficient for myofiber ERK1/2. Young adult mutant soleus was drastically wasted, with highly atrophied type 1 fibers, denervation at most synaptic sites, induction of “fetal” acetylcholine receptor gamma subunit (AChRγ), reduction of “adult” AChRε, and impaired mitochondrial biogenesis and function. In weanlings, fiber morphology and mitochondrial markers were mostly normal, yet AChRγ upregulation and AChRε downregulation were observed. Synaptic sites with fetal AChRs in weanling muscle were ~3% in control and ~40% in mutants, with most of the latter on type 1 fibers. These results suggest that: (1) ERK1/2 are critical for slow-twitch fiber growth; (2) a defective γ/ε-AChR subunit switch, preferentially at synapses on slow fibers, precedes wasting of mutant soleus; (3) denervation is likely to drive this wasting, and (4) the neuromuscular synapse is a primary subcellular target for muscle ERK1/2 function in vivo.

Mechanisms of Pi regulation of the skeletal muscle SR Ca2+ release channel

2000 ◽  
Vol 278 (3) ◽  
pp. C601-C611 ◽  
Author(s):  
Edward M. Balog ◽  
Bradley R. Fruen ◽  
Patricia K. Kane ◽  
Charles F. Louis
Keyword(s):  
Skeletal Muscle ◽  
Single Channel ◽  
Adenine Nucleotides ◽  
Muscle Fibers ◽  
Open Probability ◽  
Release Channel ◽  
High Concentrations ◽  
Channel Open Time ◽  
Stimulation Of

Inorganic phosphate (Pi) accumulates in the fibers of actively working muscle where it acts at various sites to modulate contraction. To characterize the role of Pi as a regulator of the sarcoplasmic reticulum (SR) calcium (Ca2+) release channel, we examined the action of Pi on purified SR Ca2+ release channels, isolated SR vesicles, and skinned skeletal muscle fibers. In single channel studies, addition of Pi to the cis chamber increased single channel open probability ( P o; 0.079 ± 0.020 in 0 Pi, 0.157 ± 0.034 in 20 mM Pi) by decreasing mean channel closed time; mean channel open times were unaffected. In contrast, the ATP analog, β,γ-methyleneadenosine 5′-triphosphate (AMP-PCP), enhanced P o by increasing single channel open time and decreasing channel closed time. Pi stimulation of [3H]ryanodine binding by SR vesicles was similar at all concentrations of AMP-PCP, suggesting Pi and adenine nucleotides act via independent sites. In skinned muscle fibers, 40 mM Pi enhanced Ca2+-induced Ca2+ release, suggesting an in situ stimulation of the release channel by high concentrations of Pi. Our results support the hypothesis that Pi may be an important endogenous modulator of the skeletal muscle SR Ca2+ release channel under fatiguing conditions in vivo, acting via a mechanism distinct from adenine nucleotides.

Altered E-C coupling in triads isolated from malignant hyperthermia-susceptible porcine muscle

1995 ◽  
Vol 268 (6) ◽  
pp. C1381-C1386 ◽  
Author(s):  
R. el-Hayek ◽  
M. Yano ◽  
B. Antoniu ◽  
J. R. Mickelson ◽  
C. F. Louis ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Dihydropyridine Receptor ◽  
Normal Muscle ◽  
Direct Stimulation ◽  
Release Channel ◽  
Malignant Hyperthermia Susceptible ◽  
T Tubules ◽  
Junctional Foot Protein ◽  
Stimulation Of

Triad vesicles were isolated from normal (N) and homozygous malignant hyperthermia-susceptible (MHS) porcine skeletal muscle, and two types of sarcoplasmic reticulum Ca2+ release were investigated: 1) polylysine-induced Ca2+ release (direct stimulation of the junctional foot protein), and 2) depolarization-induced Ca2+ release (stimulation of the junctional foot protein via the dihydropyridine receptor). At submaximal concentrations of polylysine, the rates of induced Ca2+ release from the MHS triads were greater than from normal triads. The T tubules of polarized triads were depolarized by the K(+)-to-Na+ ionic replacement protocol. Higher grades of T-tubule depolarization resulted in higher rates of Ca2+ release from both MHS and normal triads but, when compared at a given grade of T-tubule depolarization, the release rate was always greater from the MHS than from normal triads. Thus the activity of the SR Ca2+ release channel is always higher in MHS than in normal muscle at a given submaximal dose of release trigger. This difference is observed when the channel is stimulated directly by polylysine or indirectly via a depolarization-induced activation of the T-tubule dihydropyridine receptor.

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