The anticholinesterase activity of some antiadrenaline agents.

The contractions of the isolated guinea-pig vas deferens in response to stimulation of the sympathetic hypogastric nerve were potentiated by low concentrations and inhibited by high concentrations of the antiadrenaline agents tolazoline, yohimbine, ergotamine, phenoxybenzamine and piperoxan. Eserine potentiated the contractions of the vas deferens produced by hypogastric nerve stimulation. The cholinesterase activity of an extract of vas deferens was decreased by the antiadrenaline agents.

Transmission failure in sympathetic nerves produced by hemicholinium.

It has been shown by others that hemicholinium (alpha,alpha'-dimethylethanolamino-4,4'-biacetophenone) inhibits the synthesis of acetylcholine, an effect which is reversed by choline. Hemicholinium produces a failure of response to nerve stimulation in the following sympathetically innervated preparations: guinea-pig isolated vas deferens, rabbit isolated uterus, rabbit isolated colon, perfused rabbit ear, cat isolated atria and the piloerector muscles in the cat's tail. The blocking action of hemicholinium on the responses to postganglionic sympathetic stimulation resembles its blocking action against cholinergic nerve stimulation observed on rabbit isolated atria with vagus nerves, rabbit isolated vagina with pelvic nerves, and guinea-pig isolated diaphragm with phrenic nerve.