Halothane-induced rigidity and associated glycolytic and energy phosphate changes in red and white fibres of skeletal muscle of the pig

The exposure of a group of Piètrain pigs to halothane at the levels required to induce anaesthesia initiated muscular rigidity and hyperthermia in all individuals of the group whereas a group of Irish Landrace pigs did not respond adversely to the anaesthetic. The speed at which rigidity developed in the halothane sensitive animals was a remarkable feature of the syndrome. Biochemically, the condition was characterized by depletion of energy phosphates and extensive glycolysis in both anaerobic (white) and oxidatively metabolizing (red) myofibres in vivo. The natural actomyosin ATPase of Piètrain muscle had a slightly higher capacity to split MgATP2− than that from Landrace muscle but the difference in inherent activity was not sufficient to account for the extremely high rates of ATP turnover and glycolysis in the MHS susceptible pigs nor for the elevated rates usually associated with Piètrain muscle.