Localization of Receptors Inhibiting Gastric Emptying in the Gut

Abstract

Five dogs were prepared, each with three fistulas; one fistula was placed in the stomach, the other in the first part of the duodenum, 5 cm from the pylorus, and the third at the junction of the duodenum and the jejunum. By combinations of test meals and perfusions, either a part of or the whole duodenum or jejunum was tested with 550 to 850-milliosmolar solutions (glucose, glycine, mannitol, or sodium chloride), 100 mm HCl, 10 or 20 mm sodium oleate and 40 mm tryptophan for their effect on gastric emptying. Phenol red was used as a nonabsorbable marker. Gastric emptying was not slowed by perfusion of the whole duodenum with the hypertonic solutions of glucose, glycine, mannitol and sodium chloride, or with 10 or 20 mm sodium oleate. In contrast, significant slowing of gastric emptying occurred with jejunal perfusion of the hypertonic solutions and sodium oleate. Jejunal perfusion of 100 mm HCl slowed gastric emptying, but perfusion of the second to fourth parts of the duodenum did not. Tryptophan slowed gastric emptying when allowed to perfuse the first 5 cm of the duodenum, the second to fourth parts of the duodenum, and also the jejunum. The findings from this study indicate that the jejunum has receptors for inhibition of gastric emptying responsive to tryptophan, acid, fat, and hypertonic solutions. In contrast, the duodenum has receptors responsive to tryptophan.