In vivo induced malignant hyperthermia in pigs. II. Metabolism of skeletal muscle mitochondria.

The biochemical characteristics of skeletal muscle mitochondria of malignant hyperthermia (MH) susceptible Dutch Landrace pigs have been investigated before and during an MH attack, induced in vivo by halothane plus succinylcholine. The muscle homogenates have a decreased capacity to synthesize ATP and creatine phosphate during the MH period. Muscle mitochondria prepared from susceptible pigs in an MH period consume less oxygen than do mitochondria isolated before the attack, or mitochondria from control pigs during the challenge. The oxidative phosphorylation is not uncoupled during the critical period. The production of CO2 indicates that the in vitro measured capacity of the MH muscle mitochondria correctly reflects the in vivo condition during the MH attack. The restricted synthesis may be caused by a factor, finding expression in the mitochondria themselves, and obtained or activated during the MH attack.