The intestinal phase of gastric secretion.

The intestinal phase hormone, elaborated by the jejunum in response to an intestinal meal or simple distension, produces profound gastric hypersecretion when it escapes hepatic degradation through a portacaval anastomosis. The hormone is released within 30 min of the application of the stimulus and rapidly reaches peak concentration in the portal blood. Intravenous infusion into a donor dog of active portal plasma from a shunted, intestinally fed dog stimulates gastric acid secretion after a delay of approximately 1 h, and requires a mean 1 1/2 h to stimulate peak secretion, which suggests that intermediate steps may be necessary before the hormone can effectively stimulate the parietal cell mass. The pig develops portacaval-shunt-related gastric acid hypersecretion in response to food comparable to that observed in the dog and in man. Porcine jejunal mucosa is thus an appropriate source for isolation of the intestinal phase hormone. Pig intestinal mucosal extract contains a heat-stable acidic peptide which is a potent stimulator of gastric acid secretion. Administration of crude intestinal mucosal extract elicits gastric acid secretion after a brief delay, again indicating that some intermediate reactions occur before the target organ--the parietal cell mass--is stimulated.