Bioscience reports
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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 (RyRI) representing the major locus. Here we review recent studies characterizing the effects of MH mutations on the sensitivity of the RyRI 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 RyRI with their effects on the physiologic mechanism that activates Ca2+ release during EC coupling in intact muscle.
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Malignant hyperthermia (MH) is a pharmacogenetic disease which predisposes to the trigger of a life-threatening, hypermetabolic syndrome by potent inhaled anesthetics and by depolarizing skeletal muscle relaxants. Heat production in the anesthetized MH can be profound with 5-fold increases in oxygen consumption. ⋯ Possible mechanisms by which continuous release of calcium from skeletal muscle sarcoplasmic reticulum stores can produce the profound hyperthermia are discussed. Mutations in the gene coding the ryanodine receptor calcium release channel have been found in MH families and these mutant channels may be the functional basis for MH.