Skeletal muscle mitochondrial respiration of malignant hyperthermia-susceptible patients. Ca2+-induced uncoupling and free fatty acids.

1. Skeletal muscle mitochondria of malignant hyperthermia (MH)-susceptible patients showed normal oxidative phosphorylation but were more easily uncoupled than normal by exogenous Ca2+. 2. Fatty acids, in stimulating the mitochondrial ATPase activity, are responsible for the enhanced State 4 respiration in MH-susceptible patients. 3. These results imply that skeletal muscle mitochondria and free fatty acids are associated with the development of MH syndrome.