AJP - Gastrointestinal and Liver Physiology, Vol 247, Issue 2 171-G175, Copyright © 1984 by American Physiological Society
Bethanechol prevents inhibition of gastric acid secretion by gastric inhibitory polypeptide
P. Soon-Shiong, H. T. Debas and J. C. Brown
Earlier studies of gastric inhibitory polypeptide (GIP) have shown that it
is a powerful inhibitor of acid secretion in denervated gastric pouches.
Other studies, however, have shown that it is a weak inhibitor in
innervated stomach preparations. In this study we evaluated the inhibitory
action of GIP in four dogs, each provided with both a vagally denervated
(Heidenhain) pouch and a gastric fistula of the innervated stomach. The
effect of intravenous infusion of pure porcine GIP (1 microgram X kg-1 X
h-1) on pentagastrin dose response was studied with and without background
infusion of bethanechol (25 micrograms X kg-1 X h-1). GIP powerfully
inhibited pentagastrin-stimulated acid secretion from the Heidenhain pouch
but not from the gastric fistula. The maximal inhibition was 76% for the
Heidenhain pouch and 29% for the gastric fistula. Despite the attainment of
high levels of circulating immunoreactive GIP (greater than 3,000 pg/ml)
early after the onset of infusion of the peptide, inhibition occurred
relatively late, suggesting that this action of GIP might be mediated by
the release of some other substance(s). Background infusion of bethanechol
totally abolished the inhibitory action of GIP in both the Heidenhain pouch
and gastric fistula.
