Mg2+ dependence of Ca2+ release from the sarcoplasmic reticulum induced by sevoflurane or halothane in skeletal muscle from humans susceptible to malignant hyperthermia

In both MHS and MHN fibres (i) halothane is a more potent activator of SR Ca2+ release than sevoflurane and (ii) as with halothane, the efficacy of sevoflurane-induced SR Ca2+ release exhibits a marked dependence on cytosolic [Mg2+]. The marked potentiation of SR Ca2+ release after a moderate reduction in cytosolic [Mg2+] suggests that conditions which cause hypomagnesaemia will increase the probability and possibly severity of an MH event. Conversely, maintenance of a normal or slightly increased cytosolic [Mg2+] may reduce the probability of MH.