The vagus is a mixed nerve containing cholinerrgic and non-cholinergic neurons. Vagal fibers interact with peptidergic neurons of the enteric nervous system which stain immunohistochemically for cholecystokinin

vasoactive intestinal polypeptide

and gastrin releasing peptide. The contribution of these peptidergicneurons in the pancreatic response to vagal stimulation is unknown. We tested the effect of specific inhibitor of these stimulants against vagally mediated exocrine secretion in rats. The response to vagal stimulation was blocked significantly by each of the following:the ganglionic blocker hexamethonium （l00% inhibition）; the muscarinic

cholinergic blocker atropine （85% inhibition）; the specific cholecystokinin-A receptor blocker （91 % inhibition）; and a vasoactive intestinal polypeptide polyclonal antibody （89% inhibition）. This observation is consistent with the hypothesis that potentiating interactions among several agonists mediate the vagal response. Our study

however

dose not exclude acetylcholine as the final commommediator.