Interactions of gastric blood flow, barrier breaker, and hydrogen ion back diffusion during ulcer formation in the rat.

A rat gastric chamber preparation was used to determine the interrelations between H+ back diffusion, mucosal blood flow, the area of mucosa treated with bile salts and ulcer formation. The rate of H+ back diffusion was found to be dependent on both mucosal blood flow and the area of mucosa exposed to bile salts. It is concluded that, although H+ back diffusion is a convenient measure of barrier permeability under conditions of normal mucosal blood flow, during mucosal ischemia this parameter fails to reflect permeability because of decreased mucosal clearance of H+. These findings would explain apparent controversy whereby ulceration occurs under shock conditions in the absence of apparent H+ back diffusion.