Membrane abnormality in malignant hyperthermia.

In this study we report on the effect of halothane exposure on the skeletal muscle membrane and calcium localization in 9 patients with confirmed susceptibility to malignant hyperthermia and compare them with 11 non-susceptible cases of malignant hyperthermia. Two normal muscle specimens with physiologically induced muscle contractures were also included for comparison. Halothane exposure in malignant hyperthermia-susceptible cases showed severe muscle contractures, definite breaks in the plasma membrane with peroxidase penetration, and large number of calcium granules within the mitochondria and sarcoplasmic reticulum. Malignant hyperthermia-non-susceptible cases and muscle with physiological contractures did not show discontinuity of the plasma membrane or excessive calcium deposits. Based on these findings we conclude that the halothane exposure in malignant hyperthermia-susceptible patients causes breaks in the muscle plasma membrane.