Failure of gastric inhibitory polypeptide to inhibit pentagastrin-stimulated acid secretion in vagotomized human subjects.

Five vagotomized male subjects were given graded doses of pentagastrin without and with a background infusion of 2 microgram/kg/hr of gastric inhibitory polypeptide (GIP). An insulin infusion test (0.1 units/kg/hr) showed that the vagotomies were complete. GIP infusion failed to inhibit pentagastrin-stimulated acid and pepsin secretion even though plasma GIP concentration reached a plateau much higher than that measured after ingestion of a meal. We conclude that GIP does not inhibit pentagastrin-stimulated gastric acid secretion in vagotomized human subjects.