The role of vagal innervation in gastric and pancreatic responses to meals varying in pH.

In three dogs provided with chronic gastric and pancreatic fistulae, gastric acid response to a peptone meal was measured by a method of intragastric titration at pre-selected pH values ranging from 6.0 to 2.0 or at a constant pH during intravenous infusion of secretin in graded doses ranging from 0.25 to 4.0 u./kg.hr. Simultaneously, pancreatic secretion was determined by the standard collection technique and serum gastrin response was measured by radio-immunoassay. In this way the pH profile for the inhibition of gastric response and stimulation of pancreatic secretion as well as serum gastrin response to a peptone meal have been determined and compared with that obtained with exogenous secretin or feeding a liver meal. Truncal vagotomy resulted in a significant decrease of gastric acid response to the meal at all pH levels or at all doses of secretin but the inhibitory effect of gastric acidification or secretin on serum gastrin and gastric acid response to a meal remained unchanged. Vagotomy caused a decrease of pancreatic secretory response to meals at all pH levels and at all doses of secretin except the largest one. Pancreatic secretion stimulated by secretin alone was not affected by vagotomy, whereas that induced by feeding a liver meal was markedly decreased by this procedure. From these studies we have tentatively concluded that the vagus nerve facilitates the release of intestinal hormones and that vagotomy causes a decrease of gastric and pancreatic responses to endogenous but not to exogenous stimuli.