The Effects of a Gastric Inhibitory Substance on Gastric Secretion in the Pylorus Ligated Rat1

An extract was prepared from juice secreted by vagally denervated isolated pouches of the gastric antrum in the dog, by dialyzing against water and lyophilization. This gastric inhibitory substance (GIS) was assayed in pylorus ligated rats. Three groups of rats served as controls. One group received no injections, while the two other were injected with saline (1 ml/100 g rat) intravenously (i.v.) or intraperitoneally (i.p.). Two different types of gastric secretion were studied: (a) basal or spontaneous gastric output, and (b) gastric acid response to exogenous gastrin. GIS lowered significantly the basal or spontaneous output of acid, but did not alter the basal output of pepsin significantly. When GIS was injected into animals stimulated by gastrin, there was a highly significant lower output of both acid and pepsin.