Effects of diversion and reperfusion of pancreaticobiliary juice on amylase release from isolated rat pancreas.

Diversion of pancreaticobiliary juice from the small intestine results in resetting of the normal negative-feedback regulation of exocrine pancreatic secretion. The mechanism by which this process occurs is not well understood. To examine this regulatory process, we investigated the effects of pancreaticobiliary juice diversion and reperfusion on exocrine pancreas using isolated rat pancreatic acini. Two groups of rats were surgically prepared for pancreaticobiliary juice diversion and reperfusion. Both groups received a liquid diet via a duodenal cannula and saline by intravenous infusion for 24 hours following surgery. Forty-eight hours after the surgery and infusions, the rats were sacrificed, and acinar cells were quickly isolated from each pancreas. Amylase release from isolated acini was measured in response to doses of cholecystokinin octapeptide (CCK-8) and carbachol. Acinar cell receptor binding was measured by using CCK-8 labeled with iodine 125 and N-tritium-methscopolamine bromide as radioligands. Amylase release in response to both CCK-8 and carbachol was significantly decreased in the diversion group when compared with that of the reperfusion group. Receptor binding sites of CCK-8 and methscopolamine bromide were similar in the diversion and reperfusion groups. The results suggest that cholecystokinin- and carbachol-mediated amylase response is affected by pancreaticobiliary juice diversion through a process that most likely involves alteration of post-receptor-mediated intracellular signaling pathways.