Effects of ethanol on electrical parameters of the in vivo rat stomach

The gastric transmural electrical potential difference (PD) and direct-current resistance were measured in the rat in vivo under conditions in which the luminal pH was controlled over the pH range 1.0 to 12.0. Raising the pH above 11.0 caused a reduction in both PD and resistance. This is consistent with basic groups limiting cation permeability through the mucosa. Exposure of the mucosa to 20% ethanol caused a reduction in resistance, PD, and H+ secretion, and an increased appearance of Na+ in the lumen at neutral pH. The pH dependence of the resistance at high pH values was also eliminated, consistent with the elimination or bypassing of channels containing basic groups. Mucosal exposure to 8.5% ethanol reduced the PD and H+ secretion without affecting resistance. The increased appearance of Na+ in the lumen seen with this alcohol solution also occurred following exposure to hyperosmotic sucrose.