Action of atropine on the pancreatic secretory response to secretin before and after cutting the extrinsic nerves of the pancreas in dogs.

In two sets of dogs with gastric and pancreatic fistulas, we studied the effect of atropine on the pancreatic secretory response to intravenous secretin before and after cutting the extrinsic nerves of the pancreas, i.e., celiac and superior mesenteric ganglionectomy alone or truncal vagotomy plus celiac and superior mesenteric ganglionectomy. Neither truncal vagotomy alone nor ganglionectomy alone, nor the two together, altered the incremental bicarbonate response to secretin. Irrespective of the degree of integrity of the extrinsic vagal and splanchnic innervation of the pancreas, intravenous atropine (14 nmol/kg X h) significantly (p less than 0.05) depressed the incremental bicarbonate responses to the two lowest (5.2 and 10.3 pmol/kg X h) doses of secretin by 85% and 61%, respectively, but had no significant effect on responses to high doses. We conclude that the pancreatic bicarbonate response to secretin, and the action of atropine on that response, are independent of an intact extrinsic innervation of the gland. The observation of the persistent inhibitory action of atropine after extrinsic denervation of the pancreas is compatible with the hypothesis that endogenous cholinergic activity augments the pancreatic bicarbonate response to secretin.