Characteristics of intestinal phase of gastric secretion

In four dogs provided with special gastroduodenal fistulas allowing for the complete separation of stomach and duodenum without interrupting the vagal connections between them, the magnitude of the gastric and intestinal phases was compared and their contribution to the total gastric response to a meal was established. A liver extract (LE) meal, confined to the stomach and maintained at pH 5.0 by an intragastric titration technique, produced acid output reaching 66% of the maximal response to histamine (MRH). Perfusion of the LE meal into the duodenum resulted in acid secretion amounting to 57% of MRH. The combination of the gastric and intestinal phases caused the highest acid output, amounting to about 90% of MRH. Gastric and intestinal phases induced separately were accompanied by a significant elevation in serum gastrin concentrations which reached the highest values when both phases were evoked simultaneously. Acidification of the intestinal meal resulted in pH-dependent inhibition of gastric secretion falling to the basal values at pH 1.0. These secretory changes were mimicked by exogenous secretin. Serum gastrin levels remained essentially unaffected by the acidification of the intestinal meal while exogenous secretin significantly lowered them. In conclusion, in the intact stomach with undisturbed nervous connections between the stomach and duodenum, a peptone meal in the intestine is capable of evoking a potent gastric acid and pepsin stimulation by a mechanism involving the release of antral hormone.