Effects of Synthetic Vasoactive Intestinal Peptide (VIP), Secretin and Their Partial Sequences on Gastric Secretion

Abstract
The effects of synthetic porcine VIP [vasoactive intestinal peptide] and secretin on pentagastrin-stimulated gastric secretion were compared in dogs equipped with gastric fistulae. VIP inhibited both acid and pepsin secretion. Percent inhibition of acid secretion by VIP varied with the dose of pentagastrin: dose-response analysis showed inhibition to be of the competitive type. Percent inhibition of acid secretion by secretin did not vary with the dose of pentagastrin and was consistent with inhibition of the noncompetitive type. Carboxyl-terminal partial sequences of VIP and secretin, at approximately 10 times the molar doses of the parent peptides, had no detectable inhibitory effect.