PHARMACOLOGIC INTERACTIONS WITH 4-(m-CHLOROPHENYLCARBAMOYLOXY)-2-BUTYNYLTRIMETHYLAMMONIUM CHLORIDE, A SYMPATHETIC GANGLION STIMULANT

¹ Department of Physiology, Monash University, Victoria, Australia

With the use of isometric recordings of contractions of the cat nictitating membrane, comparisons were made between the effects on the superior cervical ganglion of intraarterial injections of some nicotinic and nonnicotinic ganglion-stimulating drugs. Selective depression of the nonnicotinic drugs, but not of 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), was observed after treatment with several drugs or raised calcium, while lowered calcium selectively potentiated the effects of the nonmcotinic drugs. Unlike the nonnicotinic stimulants, DMPP transiently depressed responses to preganglionic electrical stimulation. Moderate doses of DMPP depressed, but large doses sometimes augmented, the response to injections of 4-(m-chlorophenyicarbamyloxy-2-butynyltrimethylammonium chloride (McN-A-343). In confirmation of the work of Trendelenburg and Jones, it was found that the effects of both histamine and McN-A-343 were greatly potentiated following preganglionic stimulation. It was also shown that 5-hydroxytryptamine, but not DMPP, was similarly potentiated.