Effect of atropine on pancreatic responses to endogenous and exogenous cholecystokinin

Abstract

The role of cholinergic innervation in endogenous release of cholecystokinin from the intestinal mucosa and in exocrine pancreatic secretion was examined by means of atropine administration in 3 chronic gastric-fistula and pancreatic-fistula dogs during pancreatic responses to various rates of intraduodenal amino acid mixture and to various doses of intravenous cholecystokinin producing equal rates of pancreatic protein secretion. Atropine infused in a dose of 100 µg/kg-hr caused a deep and prolonged decrease in pancreatic flow rate, protein and bicarbonate output, reaching a maximum of about 80% of the pre-atropine level of pancreatic secretion. The inhibition occurred regardless of the level of pancreatic response examined. Atropine also caused an inhibition of pancreatic responses to smaller doses of exogenous cholecystokinin but did not affect responses to larger doses. The maximal observed pancreatic protein secretion in response to intraduodenal administration of amino acids was about 80% of the highest response to cholecystokinin. This study suggests that the release of cholecystokinin from the intestinal mucosa might be cholinergically dependent.