EFFECT OF LUMINAL PH AND NUTRIENT BICARBONATE CONCENTRATION ON RESTITUTION AFTER GASTRIC SURFACE CELL INJURY

Abstract

Frog [Rana catesbeiana] fundic mucous whose surface layers were severely injured by exposure to 1 M NaCl for 10 min in an Ussing chamber uniformly recovered both physiologically and anatomically within 4-6 h. The effects of luminal H+ and nutrient HCO3- concentrations on this process of reconstitution were examined. With 18 mM HCO3, return of the transmucosal potential difference, tissue electrical resistance and short-circuit current toward normal and anatomic recovery occurred at luminal pH 7.4, 5.0 and 4.0, but not at 3.0. An inhibitor of pepsin did not favorably affect the outcome of luminal pH 3.0, but a nutrient HCO3- concentration of 47.8 mM completely prevented the adverse effects of luminal pH 3.0. Reconstitution of epithelial integrity did not occur in the absence of HCO3- at luminal pH 4.0. Thus, low luminal pH inhibits and high nutrient HCO3- concentration supports the epithelial restitution after mucosal damage caused by hyperosmolar NaCl.