SECRETIN - A PHYSIOLOGICAL REGULATOR OF GASTRIC-EMPTYING AND ACID OUTPUT IN DOGS

Secretin has been known to inhibit gastric acid secretion in several s pecies. However, the physiological role of secretin on the postprandia l acid output and gastric emptying in an intact stomach remains contro versial. In the present study, we reinvestigated the role of secretin in physiological dose range and endogenous secretin on gastric acid se cretion and emptying in the stomach without influencing intragastric l uminal pH in dogs. In seven conscious dogs with gastric cannulas, a 4% amino acid meal was administered intragastrically, and three differen t doses of secretin and an antisecretin serum were infused intravenous ly in each dog on separate days. Gastric emptying and net acid output were measured using a dye dilution technique, and plasma secretin and gastrin were determined by specific radioimmunoassays. After the meal, gastric emptying was exponential: acid output peaked at 25 min, and p lasma concentrations of gastrin and secretin peaked at 15 and 60 min, respectively. Intravenous infusion of secretin at 1.25, 2.5, and 5.0 p mol.kg(-1).h(-1) dose dependently increased plasma levels of the pepti de and suppressed postprandial plasma gastrin response and gastric aci d output and emptying of the meal. Immunoneutralization of circulating secretin with a rabbit antisecretin serum abolished the postprandial rise of plasma secretin and significantly increased plasma gastrin, an d augmented gastric emptying as well as acid output. It is concluded t hat, in dogs, secretin plays a physiological role in the regulation of gastric emptying and acid output after a liquid amino acid meal and t hat these effects may be mediated in part by suppression of the releas e of gastrin.