Comparison of the action of cholinomimetics and pentagastrin on gastric secretion in dogs.

Stimulation of acid secretion by muscarinic cholinomimetic agents depended on the periodic interdigestive activity of the stomach. This explains the peak and following fade. Pentagastrin stimulated gastric secretion after a fixed interval and did not depend on the interdigestive activity. Neither gastrin nor methacholine directly contracted the gallbladder in the doses used. A sustained secretion of gastric acid and pepsin, such as follows a meal, required both hormonal stimulation and gastric distension. The magnitude of the acid response from Heidenhain pouches following meals suggested that pentagastrin doses commonly used experimentally greatly exceed the physiological.