AJP - Gastrointestinal and Liver Physiology, Vol 250, Issue 5 617-G624, Copyright © 1986 by American Physiological Society
Ontogeny of gastric mucosal permeability responses to luminal H+ and bile salt in the rat
B. L. Tepperman, D. B. Barr and M. C. Palmer
Gastric mucosal responses to intraluminal instillation of acid (10, 50, and
150 mM HCl) and acidified solutions of sodium taurocholate (10 mM) were
measured in rats between 5 and 60 days after birth. Net loss of H+ and gain
of Na+, K+, and protein into the gastric lumen remained low and stable up
to 25 days after birth. After that there were dose-dependent increases in
H+ loss and Na+ and K+ appearance in the gastric lumen. Luminal protein
appearance did not change with any concentration of acid tested in any of
the ages examined. Gastric instillation of sodium taurocholate resulted in
an increase in the rate of H+ loss as well as Na+ and K+ appearance in
neonatal rats after 12-14 days. Protein appeared in the recovered gastric
instillate and increased in parallel with Na+ and K+. In response to bile
salt treatment, ulcers were only evident after 35 days of age. Injection of
8-day-old rats with corticosterone acetate (250 mg/kg) did not affect the
ionic fluxes or protein output in response to acid alone or acidified bile
salt solutions. These studies indicate that intragastric acid loads did not
increase the ionic permeability of the gastric mucosa until 25 days after
birth. The permeability changes occur earlier (day 12-14) if sodium
taurocholate is added to the acid instillate. Prior to that time the
mucosal permeability characteristics of the neonatal rat stomach are not
altered by instillation of either acid loads alone or bile salt
solutions.(ABSTRACT TRUNCATED AT 250 WORDS)
