Effect of Secretin on Acid and Pepsin Secretion in Cat and Dog

Abstract

Secretin in doses which produced a maximal inhibition of gastric secretion in the dog and maximal stimulation of pancreatic secretion in the cat had no effect on gastrin-stimulated gastric secretion in the cat. Irrigation of the duodenum with acid produced a much smaller inhibition of gastrin-stimulated gastric secretion in the cat than in the dog, thus suggesting that endogenous secretin is not so important for the control of acid secretion in the cat as in the dog. We conclude that the disparity between the action of secretin on gastric secretion in the cat and dog represents a true species difference. Identical doses (on a body weight basis) of secretin, however, produced strong stimulation of pepsin secretion in both the cat and dog. Stimulation was produced by continuous intravenous infusions of secretin in doses submaximal for pancreatic secretion. In addition the effect of natural secretin was reproduced exactly by the synthetic hormone, indicating that the stimulation of pepsin secretion is a property of the secretin molecule. Endogenous secretin, released by either exogenous acid in the duodenum or by closing the gastric fistula, reproduced the effect of the exogenous secretin or pepsin secretion. We conclude, therefore, that the stimulation of pepsin secretion is a physiological action of secretin.