Oxyntomodulin (glucagon-37) and its C-terminal octapeptide inhibit gastric acid secretion

Abstract Oxyntomodulin (OXM) is a peptide isolated from porcine intestine which consists of the whole glucagon sequence with a basic octapeptide (KA 8 ) at its C-terminal end. In this study, the effect of OXM and KA 8 on pentagastrin-stimulated gastric acid secretion has been studied in conscious rats and cats. In rats, OXM (25–450 pmol·kg −1 ) as well as KA 8 (7.5–60 nmol·kg −1 ) inhibited pentagastrin-stimulated gastric acid output in a dose-dependent manner; KA 8 was about 100-times less potent than OXM. In cats, KA 8 (90 nmol·kg −1 ) was also an inhibitor of acid secretion. We conclude that OXM, or a closely related peptide, could be a physiological modulator of gastric acid secretion, and that the C-terminal octapeptide of OXM is implicated in this effect.