Abstract
The effects of gastrin, a synthetic pentapeptide (N-t-butyloxycarbonyl-β-Ala. Try. Met. Asp. Phe. NH2; I.C.I. 50,123) and histamine on the secretion of gastric acid have been compared in a perfused stomach preparation using anaesthetised rats. The pentapeptide was shown to possess similar secretory activity to that of gastrin but to be 11 times less potent on a molar basis. It produced acid secretions similar to those produced by histamine when compared in several different ways. Unlike histamine, the pentapeptide was without significant effect on blood pressure or haematocrit in maximally stimulating doses.