The effects of calmodulin antagonist drugs on isolated sarcoplasmic reticulum from malignant hyperpyrexia susceptible swine

1. 1. Because calcium antagonist drugs increase contracture in both control and malignant hyperpyrexia susceptible (MHS) skeletal muscle, the effect of these drugs on the sacroplasmic reticulum (SR) was investigated. 2. 2. The calmodulin antagonist drugs inhibited the Ca 2+ dependent ATPase activity and the ATP-dependent Ca 2+ uptake, and accelerated the efflux of Ca 2+ from isolated SR preparations from both control and MHS skeletal muscle. These effects of calmodulin antagonist drugs on SR Ca 2+ transport functions were consistent with their in vitro pharmacological effects on control and MHS muscle.