Tracheal smooth muscle relaxant effect of ketamine

Abstract

Ketamine is claimed to decrease airways resistance in patients suffering from broncho-constriction. Investigations of its mechanism of action were undertaken using the guineapig tracheal chain, a preparation which reacts to drugs in a manner similar to that of the smooth muscle of human bronchioles. Ketamine was found to possess a direct relaxant effect on the tracheal chain, to antagonize the spasmogenic effects of carbachol and potentiate the antispasmodic effects of adrenaline. Reduction in airway resistance after ketamine anaesthesia is probably the result of a direct relaxant effect on bronchial smooth muscle and a changed response to endogenous humoral substances. © 1974 John Sherratt and Son Ltd.