Non-step intracellular voltage response of epithelial and oxyntic cells in frog gastric mucosa

Intracellular analyses of the electrical potential response to current pulses were performed in epithelial and oxyntic cells of the frog gastric mucosa. Independently of the use of Cl- or SO(2-)4 solutions and of the transmucosal potential difference measured, the resistance and slow potential changes observed across the mucosal surface of epithelial cells are not different from those registered across the serosal surface. In the oxyntic cells the resistance and slow potential changes are significantly higher across the mucosal than across the serosal surface, when the solution in contact with the serosal surface is positive with respect to the solution in contact with the mucosal surface. These differences were not observed when the transmucosal potential difference was reversed. It is proposed that the ionic concentration changes, by effect of current flow across the mucosa, occur in the oxyntic cells and that these changes are the origin of the slow transmucosal potential change. The epithelial cells act as a passive shunt.