Role of vagus nerves and gastrin in the gastric phase of acid secretion in male anesthetized rats.

We used the pylorus ligation model to determine the role of vagus nerves and gastrin in acid secretion induced by mechanical and chemical stimulation of the gastric lumen in anesthetized male rats. Gastric distension induced by intragastric instillation of saline resulted in a 17-fold increase in acid secretion over the basal level without an alteration in serum gastrin levels. Distension-stimulated acid secretion was inhibited by bilateral subdiaphragmatic vagotomy but not by CI-988, a gastrin receptor antagonist. Intragastric peptone produced a 71-fold increase in acid secretion over the basal level that was accompanied by a significant increase in serum gastrin levels. Whereas vagotomy almost abolished peptone-stimulated acid secretion, CI-988 inhibited peptone-stimulated acid secretion by only 50%. We conclude that the vagus nerves mediate acid secretion by mechanical and chemical stimulation and that gastrin mediates acid secretion partly by chemical stimulation but not by mechanical stimulation in anesthetized male rats.