Glucose-induced release of immunoreactive gastric inhibitory polypeptide (IR-GIP) into the duodenal lumen in man.

Duodenal juice was collected before and after an intragastric infusion of 300 ml 25% glucose in five healthy subjects. After extraction with 95% ethanol, IR-GIP in duodenal juice was determined by radioimmunoassay and found to increase from mean basal level of 63 pmol/l to a mean peak of 354 pmol/l after the glucose infusion. The elution diagrams of IR-GIP in glucose-stimulated duodenal juice and the corresponding plasma from a 16 X 400 mm Sephadex G-50 Fine column were similar, and the radioimmunoassay dilution curves of porcine GIP and duodenal juice IR-GIP were superimposable.