Calcium currents and asymmetric charge movement in malignant hyperpyrexia.

In both control pigs and pigs susceptible to malignant hyperpyrexia (MH), the size of the calcium current (ICa) and the amount of asymmetric charge movement varied considerably between different gracilis muscle fibers but appeared to vary in parallel. The mean amount of both ICa and charge movement were slightly but significantly smaller in MH-susceptible (MHS) muscle compared with normal muscle. Halothane (1% v/v) reduced both parameters by almost 50%. One interpretation of the data is that the signal, which couples depolarization to calcium release from the sarcoplasmic reticulum, is abnormal in MHS muscle.