The effect of electrical vagal stimulation on canine pancreatic exocrine function

The effect of electrical vagal stimulation on canine pancreatic exocrine function was studied in conscious dogs by stimulating intact thoracic vagus nerves, the distal ends of cut vagus nerves in animals with intact gastric denervation, and the distal ends of cut vagus nerves in dogs whose stomachs had been previously selectively denervated. The effectiveness of the stimulus was confirmed by monitoring gastric hydrogen ion output. The results indicate that stimulation of intact nerves produced minimal alteration in pancreatic output and bicarbonate and protein secretion while significantly increasing gastric fistula hydrogen ion output. Stimulation of the distal ends (efferent fibers) of cut vagus nerves in dogs with intact gastric innervation significantly increased the volume and protein output of the pancreas and the acid output of the stomach. Stimulation of the distal ends of cut right and both vagus nerves in dogs whose stomach had been denervated previously, again, significantly increased the volume and protein output of the pancreas without stimulation of stomach hydrogen ion output. The data presented in this study suggest that the canine pancreas is innervated directly by vagal fibers, which when stimulated produce an increase in protein (enzyme) output and volume of secretion. Maintenance of the pancreatic response following denervation of the stomach suggests that the response is primarily the result of direct vagal innervation and is not produced by gastrin released from the antrum.