As early as 1939, the ability of human gastric juice to inhibit gastric secretion when administered intravenously to dogs was described. Subsequent investigations showed a similar effect of human saliva on animals. The nature of the gastric secretion-inhibiting substances identified in human gastric juices and in human saliva remains unknown. Exploring this subject, Menguy and Berlinski1 collected from healthy fasting subjects saliva and secretions from the ducts of parotid, submaxillary, and sublingual glands. The samples of saliva were dialyzed and lyophilized. The material was dissolved in a phosphate buffer and administered intravenously to experimental, anesthetized animals. The amount of gastric inhibitory substance in a measured sample of saliva or glandular secretion was estimated by the percentage of inhibition of gastric secretion as compared to that of the controls.
The concentration of gastric inhibitory substance in whole human saliva appeared to depend predominantly on the secretions from the sublingual glands. Since