Diltiazem inhibits halothane-induced contractions in malignant hyperthermia-susceptible muscles in vitro.

The ability of diltiazem to suppress halothane and halothane-caffeine induced contractures in malignant hyperthermia (MH) susceptible pig muscle, was tested in vitro. Muscle specimens were divided into two groups and tested with a modified halothane-caffeine contracture test. One group acted as the control; the other group was pretreated with diltiazem 20 mumol litre-1. The control muscles developed contractures attributable to halothane and halothane-caffeine, whereas the diltiazem-treated specimens did not. Increases in muscle twitch tension as a result of halothane or halothane-caffeine exposure occurred in treated and untreated specimens, but were significantly delayed in the presence of diltiazem. Muscle exhaustion observed after halothane and halothane-caffeine exposure in the control specimens did not occur in the diltiazem treated muscles.