In vitro effect of ephedrine, adrenaline, noradrenaline and isoprenaline on halothane-induced contractures in skeletal muscle from patients potentially susceptible to malignant hyperthermia

Abstract

Summary: We have measured the effects of ephedrine, adrenaline, noradrenaline and isoprenaline on halothaneinduced contractures in muscle biopsies from patients potentially susceptible to malignant hyperthermia (MH). At concentrations of 4-24 mmol litre-1, ephedrine induced in vitro contractures in halothane 0.44 mmol litre-1-prechallenged muscle, whilst adrenaline, noradrenaline and isoprenaline had no effect. There was a shift of the ephedrine concentration-response curve to theleft and an increased maximum muscle contracturein the MH susceptible group compared with the MH negative group (P < 0.001). We conclude that ephedrine increased halothane-induced muscle contractures in vitro either by an unknown pharmacological mechanism or by an adrenergic stimulation which was different from those of the other investigatedadrenoceptoragonists. (Br. J. Anaesth. 1993; 70:76-79) © 1993 British Journal of Anaesthesia.