ROLE OF ANTRUM IN REGULATION OF PANCREATICOBILIARY SECRETION IN HUMANS

Little is known about the role of the gastric phase in the postprandia l pancreaticobiliary response. We evaluated the effect of antral diste nsion on pancreatic, biliary, and gastric secretions and on the releas e of cholecystokinin (CCK), gastrin, and pancreatic polypeptide in fiv e healthy volunteers. Studies were performed using a duodenal tube wit h an inflatable balloon in the antrum and a separate gastric tube. Out puts were compared with responses to a maximal CCK stimulus (caerulein ), and the role of cholinergic mechanisms was investigated using atrop ine. Graded antral distension by 50-, 200-, and 350-ml balloon volumes and constant antral distension by 350 ml elicited a marked stimulatio n of pancreaticobiliary secretions. Mean lipase outputs amounted to 52 -60%, and mean bilirubin outputs reached 14-22% of maximal. Atropine c ompletely abolished pancreaticobiliary responses to antral distension. Antral distension did not affect bicarbonate and gastric secretions. Plasma pancreatic polypeptide levels increased markedly during antral distension, and this effect was completely suppressed by atropine. The re were no changes in circulating gastrin and CCK. These data demonstr ate that antral distension with already small volumes of 50 ml elicits a hitherto unknown potent stimulatory effect, indicating a major role of the antrum in the postprandial pancreaticobiliary response in huma ns, which is mediated by cholinergic mechanisms.