Chemical concentration gradients and electrical properties of gastric mucosa

Abstract

This study explored the possibility that each surface of the gastric epithelial cell contains ion transport systems contributing to the observed transmucosal potential difference ( Vt). The model proposes that Vt arises from a K+ and Cl– diffusion potential across the submucosal face of the epithelial cells in series with the potential generated by electrogenic transport of H+ and Cl– across the mucosal face. The bio-electric effects of changes in the ionic composition of the bathing media and the tissue composition data were used to test this hypothesis. Vt varied with the log of submucosal K+ at constant Cl– and with the log of submucosal Cl– at constant K+; the sum of the slopes averaged 50 mv. Simultaneous tenfold changes in K+ and Cl– in the submucosal solutions resulted in a 53-mv change in Vt, a reasonable agreement with the theoretical value of 58 mv for a system in which the total electrical conductance is given by the sum of the K+ and Cl– conductances. Alterations in Na+ at either surface had no appreciable effect on Vt. Chemical analysis of gastric mucosae and plasma revealed the predicted pattern of K+ (mucosa) > K+ (extracellular), Na+ (mucosa) < Na+ (extracellular), and Cl– (mucosa) < Cl– (extracellular).