DIFFERENCES BETWEEN ATROPINE-LIKE AND GANGLIONIC BLOCKING AGENTS IN THEIR ACTION ON THE MOUSE PUPIL

¹ Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois

The influence of carbaminoylcholine (Cch, 2 mg/kg, s.c.) on the mydriasis produced by cholinergic blocking agents was determined in mice. Pretreatment with Cch did not alter the mydriasis produced by atropine, scopolamine, and benactyzine (tertiary amines having postganglionic parasympathetic blocking property). On the other hand, the mydriatic effect of ganglionic blocking agents (hexamethonium, mecamylamine, and p-phenylbenzyl tropanium bromide) was inhibited by Cch. The pretreatment decreased to a variable but not significant extent the mydriatic effect of those quaternary ammonium compounds which have both atropinelike and ganglionic blocking properties.

The interaction found between Ceh and cholinergic blocking drugs (atropine-like and ganglionic blocking) on the mouse pupil appears to be useful in determining their site of cholinergic blockade. The method is not suitable for measuring the absolute quantity of the ganglionic blocking action of drugs which exhibit both ganglionic and postganglionic blockade, but may give an estimate of the predominance of one or the other action.