Effect of atropine on pancreatic responses to endogenous and exogenous secretin

The role of cholinergic innervation in endogenous release of secretin from the intestinal mucosa, and in exocrine pancreatic secretion was examined by means of atropine administration in 4 chronic gastric-fistula and pancreatic-fistula dogs during pancreatic response to various doses of synthetic secretin and to various rates of intraduodenal acid load. Atropine infused in a dose of 100µg/kg/hr caused a deep and prolonged decrease of pancreatic flow rate and bicarbonate output reaching a maximum of about 70% of the pre-atropine level of pancreatic secretion. The inhibition occurred regardless of the level of pancreatic response examined, and no significant difference between the effects of atropine on pancreatic responses to exogenous and endogenous secretin was found. Intraduodenal infusion of atropine caused significantly greater inhibition of the pancreatic response to intestinal acidification than that to exogenous secretin. This suggests that release of secretin from the intestinal mucosa might be under the cholinergic control of local nerves.