Cocaine-like effect of ketamine on vascular adrenergic neurones

Abstract

The influence of ketamine on adrenergic and cholinergic responses was studied in the rabbit pulmonary artery in vitro. Ketamine and cocaine potentiated smooth muscle contractions elicited by nonadrenaline, adrenaline and transmural electrical stimulation of adrenergic neurone terminals. Arterial contractions elicited by tyramine were enhanced by ketamine, while cocaine blocked them. Ketamine moved the concentration-response curve of carbachol slightly to the right. Nicotine-induced contractions were blocked by ketamine and cocaine. The adrenergic neurone blocking effect of bretylium and dimethylphenylpiperazinium on the response to transmural stimulation was prevented by ketamine. The uptake of 3H-noradrenaline by rabbit isolated aorta was inhibited by ketamine and cocaine. It is concluded that ketamine inhibits the membrane amine pump in the terminals of postganglionic adrenergic neurones in a cocaine-like manner. © 1973.