MECHANICAL-PROPERTIES OF NORMAL AND MALIGNANT HYPERTHERMIA SUSCEPTIBLE PORCINE MUSCLE - EFFECTS OF HALOTHANE AND OTHER DRUGS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 213  (1) , 91-96
Abstract
Malignant hyperthemia, which can be initiated in susceptible humans and swine by the volatile anesthetic halothane [HT], appears to result from abnormal responses in skeletal muscle. The primary defect in susceptible muscles was inferred by observing their responses to certain drugs. The responses of cut muscle cell preparations, such as those used in the diagnostic caffeine test, were compared with those of intact muscle cells. The effects of HT, caffeine [CF], succinylcholine [SC] and catecholamines [CM] on the mechanical properties of intact muscle cells from normal pigs, mice and frogs and susceptible pigs were investigated. The results from intact and paired cut cell preparations were qualitatively similar. HT (2%) caused a 30% decrease in peak tetanic tension in susceptible porcine muscle but < 10% change in other muscles. HT potentiated twitch tension in frog and susceptible pig muscle. The latter was 4 times more sensitive to CF twitch potentiation than normal muscle. Porcine intercostal muscles were more sensitive to CF than limb extensor muscles, and the difference between normal and susceptible muscle was less with intercostal muscles. SC and CM had small and opposite effects on porcine muscles; when used together in combination with HT there was little effect on normal muscle but a dramatic decrease in tetanic tension and rapid onset of contracture in susceptible muscle.