Porcine malignant hyperthermia. VI: the effects of bilateral adrenalectomy and pretreatment with bretylium on the halothane-induced response.

The effects of bilateral adrenalectomy, together with the i.v. administration of bretylium tosylate 20 mg kg-1 on halothane-induced malignant hyperthermia (MH), were investigated in six Pietrain pigs. All six animals survived the halothane challenge, and failed to show any signs of increased muscle metabolism. Bilateral adrenalectomy alone prevented halothane-induced MH in three out of four Pietrain pigs, whereas the i.v. administration of bretylium alone protected only one pig out of an additional four animals studied. The results show that complete adrenergic blockade inhibits the susceptibility of Pietrain skeletal muscle to halothane and that the adrenal medulla makes an important contribution to this response.