COMPARISON OF DRUG-RECEPTOR DISSOCIATION CONSTANTS AT THE MAMMALIAN NEUROMUSCULAR JUNCTION IN THE PRESENCE AND ABSENCE OF HALOTHANE

¹ Department of Anaesthesia, Peter Bent Brigham Hospital, and Department of Pharmacology, Harvard Medical School, Boston, Massachusetts

The dissociation constants of tubocurarine and pancuronium were measured in guineapig lumbrical muscles in the presence of 0 to 4% halothane. The anesthetic did not alter the affinity of the receptor for either neuromuscular blocking agent. Since halothane produced no observable alteration of the receptor, halothane's antagonism of drug-induced depolarization of the neuromuscular junction appears to be exerted at a stage subsequent to reaction with the receptor.