OBSERVATIONS ON THE SELECTIVITY OF STIMULANT ACTION OF 4-(m-CHLOROPHENYLCARBAMOYLOXY)-2-BUTYNYLTRI-METHYLAMMONIUM CHLORIDE ON SYMPATHETIC GANGLIA

¹ Department of Physiology, Monash University, Victoria, Australia

The nonnicotinic ganglion stimulant 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium chloride (McN-A-343), was studied for parasympathomimetic activity in cats in vivo and in isolated rat intestine, and was found to have 0.01 to 0.001 of the potency of methacholine. Doses of hemicholinium which abolished the effects of 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) on the isolated rat ileum did not alter the actions of McN-A-343, supporting the view of Roszkowski (1961) that McN-A-343 lacks potent stimulant action in parasympathetic ganglia, but is selective for the sympathetic system. McN-A-343 was shown to have some inhibitory action on the isolated rat intestine, apparently by a nonadrenergic mechanism similar to that described by Burnstock et at. (1964). Pressor responses to McN-A-343, but not to DMPP, in cats were found to be antagonized by physostigmine, neostigmine, procaine and pronethalol. The amplitude of the pressor response to McN-A-343 was shown to vary in different species.