Gastric mucosal blood flow in ethanol-induced mucosal damage in the rat

Gastric mucosal blood flow in ethanol-induced mucosal damage was studied in urethane-anaesthetised rats by reference to ¹⁴C-aminopyrine clearance in the gastric mucosa. Irrigation of the stomach with 30% ethanol in acid saline (100 mM HCl plus 50 mM NaCl) for 40 min broke the gastric mucosal barrier, as indicated by an increased outflow of Na⁺ and K⁺ ions and back-diffusion of H⁺ ions. Gastric mucosal blood flow also increased about 2-fold, decreasing after cessation of ethanol irrigation along with the net ion fluxes. The increase in gastric mucosal blood flow occasioned by 10, 20 and 30% ethanol in acid saline was directly proportional to the net fluxes of H⁺, Na⁺ and K⁺ ions. When the stomach was irrigated with 30% ethanol in a less acid medium (10 mM HCl, 90 mM choline chloride plus 50 mM NaCl) there was still a significant increase in the outflow of Na⁺ and K⁺ ions, but only a slight back-diffusion of H⁺ ions. During this low rate of acid back-diffusion 30% ethanol reduced gastric mucosal blood flow by about 50%. The results suggest that ethanol-induced mucosal damage in the rat is associated with an increase in gastric mucosal blood flow only if combined with back-diffusion of H⁺ ions.