Tonic suppression of gastric acid secretion by endogenous peptides
in neonatal rats.
Rao, R. K., S. Pepperl, and F. Porreca.
Department of Pharmacology, University of Arizona College of
Medicine, Health Sciences Center, Tucson, Arizona 85724
APStracts 2:0111G, 1995.
Stimulation of gastric acid secretion by secretagogues were measured
in developing rats by in vivo and in vitro techniques. Basal acid
outputs in vivo were very low in 8 and 14 day rats as compared to
those in 20 and 30 day rats. In 20 day rats, all secretagogues
increased acid output in vivo, while only carbachol, pentagastrin and
CCK8s were active in 14 day rats. In contrast, basal acid output in
vitro and stimulation by secretagogues did not differ significantly
with age. CCK8s-stimulated acid output in vitro in 14 day rat was
blocked by L-365,260, L-364,718, tetrodotoxin and atropine, but not
by hexamethonium, while gastrin-stimulated acid output was blocked
only by L-365,260. Furthermore, acid output in vivo was elevated 3-4
fold by subcutaneous naloxone-methiodide or L-364,718, but not by L
-365,260, in 14 day rats; none of these antagonists produced an effect
in 20 day rats. These studies show that low basal gastric acid output
in neonatal rats is caused by tonic inhibitory regulation by
endogenous regulatory peptides.
Received 17 November 1994; accepted in final form 22 May 1995.
APS Manuscript Number G453-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 June 1995.