Factors Influencing the Action of Morphine on Acetylcholine Release in the Guinea‐pig Intestine

Morphine depresses the resting output of acetylcholine (Ach) in the guinea-pig ileum (Schaumann, 1957) and also the raised output following electrical stimulation Since the latter effect is consistent with a site of action of morphine on post- ganglionic cholinergic nerves in the intestine This possibility is supported by procaine (10 ug/ml.), hemicholinium, lowered calcium, raised magnesium, and cooling to 250 C. In the present study we have sought further information of the site of action of morphine in the resting intestine by examining its inhibitory effect under a variety of conditions which modify nerve transmission and/or neuro- transmitter release.