Effect of ethanol on canine gastric epithelial ultrastructure and transmucosal potential difference.

We correlated changes in the gastric transmucosal potential difference (PD), as an indicator of the integrity of the gastric mucosal barrier, with morphological evidence of injury in dogs which had received either intragastric saline or 5, 10, 15, or 30% ethanol. Increasing degrees of morphological damage were accompanied by greater, more rapid changes in PD. Furthermore, ultrastructural changes occurred within surface epithelial cells, not in the deeper parietal or zymogen cells, and initially did not involve disruption of the apical cell membrane. Typically, the tight junctions also were not affected, although in a minority of dogs small bleblike separations of the tight junctions were seen. We consider the gastric mucosal barrier to be represented morphologically by the interconnecting sheet of gastric epithelial cells and that ethanol breaks the barrier by first causing intracellular injury.