Ontogeny of gastric mucosal permeability responses to luminal H+ and bile salt in the rat
Tepperman, B.L.; Barr, D.B.; Palmer, M.C.
American Journal of Physiology 250(5 Pt 1): G617-G624
1986
ISSN/ISBN: 0002-9513 PMID: 3010735 Document Number: 275412
Gastric mucosal responses to intraluminal instillation of hydrochloric acid (10, 50 and 150 mM) and acidified solutions of sodium taurocholate (10 mM) were estimated in rats between 5 and 60 days after birth. Net loss of hydrogen+ and gain of sodium+, potassium+ 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 to 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 old. Injection of corticosterone acetate (250 mg/kg) did not affect the ionic fluxes or protein output in response to acid alone or acidified bile salt solutions. The 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 to 14) if sodium taurocholate is added to the acid instillate. Before that time the mucosal permeability characteristics of the neonatal rat stomach are not changed by instillation of acid loads alone or bile salt solutions. The development of the permeability response of the neonatal rat stomach to acid or bile salts does not seem to be affected by administration of adrenal steroids.