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.

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 Oral Administration of the Endocannabinoid Anandamide during Lactation: Effects on Hypothalamic Cannabinoid Type 1 Receptor and Food Intake in Adult Mice

2017 ◽  
Vol 2017 ◽  
pp. 1-5 ◽  
Author(s):  
Carolina Aguirre ◽  
Valeska Castillo ◽  
Miguel Llanos
Keyword(s):  
Food Intake ◽  
Oral Dose ◽  
Specific Binding ◽  
Binding Ability ◽  
Western Blots ◽  
Cannabinoid Type 1 Receptor ◽  
Adult Mice ◽  
And Control ◽  
Old Mice

We have previously shown that administration of the endocannabinoid anandamide (AEA) during lactation leads to overweight, increased body fat accumulation, and insulin resistance in adult mice. This study was designed to elucidate if these effects are due to increased food intake, stimulated by an augmented abundance and binding ability of the hypothalamic cannabinoid type 1 receptor (CB1R). With this aim, male mice pups were treated with a daily oral dose of AEA during lactation. Adult mice were also treated with a single oral dose of AEA, to evaluate acute food intake during 4 h. At 21 and 160 days, CB1R protein abundance was calculated by western blot analysis. Capacity of hypothalamic membranes to specifically bind the radioligand3[H]-CP55.940 was also measured. Western blots showed a 72% increase in CB1R abundance in AEA-treated 21-day-old mice, without differences in adult mice. Additionally, specific binding of3[H]-CP55.940 to hypothalamic membranes from adult mice was significantly lower in those mice treated with AEA during lactation. Moreover, AEA did not stimulate acute food intake in both, AEA-treated and control mice. Results suggest that metabolic alterations found in adult mice because of AEA treatment during lactation are not associated with hypothalamic CB1R.

scholarly journals PKA phosphorylation activates the calcium release channel (ryanodine receptor) in skeletal muscle

2003 ◽  
Vol 160 (6) ◽  
pp. 919-928 ◽  
Author(s):  
Steven Reiken ◽  
Alain Lacampagne ◽  
Hua Zhou ◽  
Aftab Kherani ◽  
Stephan E. Lehnart ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Calcium Release Channel ◽  
Skeletal Muscle Function ◽  
Release Channel ◽  
Fk506 Binding Protein ◽  
Ec Coupling ◽  
Increased Activity

The type 1 ryanodine receptor (RyR1) on the sarcoplasmic reticulum (SR) is the major calcium (Ca2+) release channel required for skeletal muscle excitation–contraction (EC) coupling. RyR1 function is modulated by proteins that bind to its large cytoplasmic scaffold domain, including the FK506 binding protein (FKBP12) and PKA. PKA is activated during sympathetic nervous system (SNS) stimulation. We show that PKA phosphorylation of RyR1 at Ser2843 activates the channel by releasing FKBP12. When FKB12 is bound to RyR1, it inhibits the channel by stabilizing its closed state. RyR1 in skeletal muscle from animals with heart failure (HF), a chronic hyperadrenergic state, were PKA hyperphosphorylated, depleted of FKBP12, and exhibited increased activity, suggesting that the channels are “leaky.” RyR1 PKA hyperphosphorylation correlated with impaired SR Ca2+ release and early fatigue in HF skeletal muscle. These findings identify a novel mechanism that regulates RyR1 function via PKA phosphorylation in response to SNS stimulation. PKA hyperphosphorylation of RyR1 may contribute to impaired skeletal muscle function in HF, suggesting that a generalized EC coupling myopathy may play a role in HF.

Malignant Hyperthermia: An Inherited Disorder of Skeletal Muscle Ca2+ Regulation

2001 ◽  
Vol 21 (2) ◽  
pp. 155-168 ◽  
Author(s):  
Charles F. Louis ◽  
Edward M. Balog ◽  
Bradley R. Fruen
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Muscle Relaxants ◽  
Release Channel ◽  
Major Locus ◽  
Channel Proteins ◽  
Ec Coupling ◽  
Physiologic Mechanism ◽  
Intact Muscle ◽  
Life Threatening

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle characterized by muscle contracture and life-threatening hypermetabolic crisis following exposure to halogenated anesthetics and depolarizing muscle relaxants during surgery. Susceptibility to MH results from mutations in Ca2+ channel proteins that mediate excitation–contraction (EC) coupling, with the ryanodine receptor Ca2+ release channel (RyR1) representing the major locus. Here we review recent studies characterizing the effects of MH mutations on the sensitivity of the RyR1 to drugs and endogenous channel effectors including Ca2+ and calmodulin. In addition, we present a working model that incorporates these effects of MH mutations on the isolated RyR1 with their effects on the physiologic mechanism that activates Ca2+ release during EC coupling in intact muscle.

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 A malignant hyperthermia–inducing mutation in RYR1 (R163C): alterations in Ca2+ entry, release, and retrograde signaling to the DHPR

2010 ◽  
Vol 135 (6) ◽  
pp. 619-628 ◽  
Author(s):  
Eric Estève ◽  
José M. Eltit ◽  
Roger A. Bannister ◽  
Kai Liu ◽  
Isaac N. Pessah ◽  
...  
Keyword(s):  
Malignant Hyperthermia ◽  
Conformational Changes ◽  
Rank Order ◽  
Decay Rates ◽  
Release Channel ◽  
Bidirectional Signaling ◽  
New Findings ◽  
Rate Of Decay ◽  
Retrograde Signal

Bidirectional signaling between the sarcolemmal L-type Ca2+ channel (1,4-dihydropyridine receptor [DHPR]) and the sarcoplasmic reticulum (SR) Ca2+ release channel (type 1 ryanodine receptor [RYR1]) of skeletal muscle is essential for excitation–contraction coupling (ECC) and is a well-understood prototype of conformational coupling. Mutations in either channel alter coupling fidelity and with an added pharmacologic stimulus or stress can trigger malignant hyperthermia (MH). In this study, we measured the response of wild-type (WT), heterozygous (Het), or homozygous (Hom) RYR1-R163C knock-in mouse myotubes to maintained K+ depolarization. The new findings are: (a) For all three genotypes, Ca2+ transients decay during prolonged depolarization, and this decay is not a consequence of SR depletion or RYR1 inactivation. (b) The R163C mutation retards the decay rate with a rank order WT > Het > Hom. (c) The removal of external Ca2+ or the addition of Ca2+ entry blockers (nifedipine, SKF96365, and Ni2+) enhanced the rate of decay in all genotypes. (d) When Ca2+ entry is blocked, the decay rates are slower for Hom and Het than WT, indicating that the rate of inactivation of ECC is affected by the R163C mutation and is genotype dependent (WT > Het > Hom). (e) Reduced ECC inactivation in Het and Hom myotubes was shown directly using two identical K+ depolarizations separated by varying time intervals. These data suggest that conformational changes induced by the R163C MH mutation alter the retrograde signal that is sent from RYR1 to the DHPR, delaying the inactivation of the DHPR voltage sensor.

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.

Functional analysis of the R1086H malignant hyperthermia mutation in the DHPR reveals an unexpected influence of the III-IV loop on skeletal muscle EC coupling

2004 ◽  
Vol 287 (4) ◽  
pp. C1094-C1102 ◽  
Author(s):  
Regina G. Weiss ◽  
Kristen M. S. O’Connell ◽  
Bernhard E. Flucher ◽  
Paul D. Allen ◽  
Manfred Grabner ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Voltage Dependence ◽  
Charge Movement ◽  
Caffeine Concentration ◽  
Maximal Conductance ◽  
Release Channel ◽  
Ec Coupling ◽  
Negative Allosteric Modulator ◽  
Similar Decrease

Malignant hyperthermia (MH) is an inherited pharmacogenetic disorder caused by mutations in the skeletal muscle ryanodine receptor (RyR1) and the dihydropyridine receptor (DHPR) α1S-subunit. We characterized the effects of an MH mutation in the DHPR cytoplasmic III-IV loop of α1S (R1086H) on DHPR-RyR1 coupling after reconstitution in dysgenic (α1S null) myotubes. Compared with wild-type α1S, caffeine-activated Ca2+ release occurred at approximately fivefold lower concentrations in nonexpressing and R1086H-expressing myotubes. Although maximal voltage-gated Ca2+ release was similar in α1S- and R1086H-expressing myotubes, the voltage dependence of Ca2+ release was shifted ∼5 mV to more negative potentials in R1086H-expressing myotubes. Our results demonstrate that α1S functions as a negative allosteric modulator of release channel activation by caffeine/voltage and that the R1086H MH mutation in the intracellular III-IV linker disrupts this negative regulatory influence. Moreover, a low caffeine concentration (2 mM) caused a similar shift in voltage dependence of Ca2+ release in α1S- and R1086H-expressing myotubes. Compared with α1S-expressing myotubes, maximal L channel conductance ( Gmax) was reduced in R1086H-expressing myotubes (α1S 130 ± 10.2, R1086H 88 ± 6.8 nS/nF; P < 0.05). The decrease in Gmax did not result from a change in retrograde coupling with RyR1 as maximal conductance-charge movement ratio ( Gmax/Qmax) was similar in α1S- and R1086H-expressing myotubes and a similar decrease in Gmax was observed for an analogous mutation engineered into the cardiac L channel (R1217H). In addition, both R1086H and R1217H DHPRs targeted normally and colocalized with RyR1 in sarcoplasmic reticulum (SR)-sarcolemmal junctions. These results indicate that the R1086H MH mutation in α1S enhances RyR1 sensitivity to activation by both endogenous (voltage sensor) and exogenous (caffeine) activators.

Characterisation of Type 2N von Willebrand Disease Using Phenotypic and Molecular Techniques

1996 ◽  
Vol 75 (06) ◽  
pp. 959-964 ◽  
Author(s):  
I M Nesbitt ◽  
A C Goodeve ◽  
A M Guilliatt ◽  
M Makris ◽  
F E Preston ◽  
...  
Keyword(s):  
Direct Sequencing ◽  
Von Willebrand Disease ◽  
Molecular Techniques ◽  
Haemophilia A ◽  
Binding Region ◽  
Gene Encoding ◽  
Covalently Linked ◽  
Von Willebrand ◽  
Willebrand Factor

Summaryvon Willebrand factor (vWF) is a multimeric glycoprotein found in plasma non covalently linked to factor VIII (FVIII). Type 2N von Willebrand disease (vWD) is caused by a mutation in the vWF gene that results in vWF with a normal multimeric pattern, but with reduced binding to FVIII.We have utilised methods for the phenotypic and genotypic detection of type 2N vWD. The binding of FVIII to vWF in 69 patients, 36 with type 1 vWD, 32 with mild haemophilia A and one possible haemophilia A carrier with low FVIII levels was studied. Of these, six were found to have reduced binding (five type 1 vWD, one possible haemophilia A carrier), DNA was extracted from these patients and exons 18-23 of the vWF gene encoding the FVIII binding region of vWF were analysed. After direct sequencing and chemical cleavage mismatch detection, a Thr28Met mutation was detected in two unrelated individuals, one of whom appears to be a compound heterozygote for the mutation and a null allele. No mutations were found in the region of the vWF gene encoding the FVIII binding region of vWF in the other four patients

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