Studies on a Gastric inhibitory Substance Isolated from Juice of the Gastric Antrum in the Dog

Six mongrel dogs were prepared with vagally denervated antral pouches and Heidenhain fundic poucnes. An extract was prepared from juice secreted by the antrum by dialyzing against water and lyophilization. This gastric inhibitory substance (GIS) was assayed in the dog from which it was prepared. Three types of gastric secretion were studied: histamine-stimulated (50-200 µg per hour i.v.), gastrin-stimulated (1-3 mg per hour i.v.), and the response to a test meal consisting of 200 g strained beef liver homogenate. GIS injected in doses of I mg/kg body weight in a single i.v. dose reduced gastric acid secretion by 50-75 per cent. The gastric secretion of pepsin was not significantly altered by the injection of GIS. No severe side reactions were observed after the injection of GIS, except an elevation of body temperature. However, the relation between body temperature and inhibition was probably different from that encountered by others utilizing bacterial pyrogen.