Clinical observations suggest that patients with portal hypertension are more prone to erosive gastritis. To test this hypothesis we investigated gastric mucosa of rats with portal hypertension (produced by staged portal vein occlusion) and sham-operated controls before and after intragastric taurocholate. Portal pressure was 36 +/- 3 cm saline in portal hypertensive rats compared with 16 +/- 2 cm in controls (P less than 0.01). Before taurocholate no macroscopic or histologic spontaneous mucosal damage was present, but portal hypertensive rats had extensive submucosal edema. Three hours after intragastric taurocholate (2 ml, 80 mM in 0.1 N HCl), macroscopic injury comprised 13.7 +/- 1.1% of mucosal surface in portal hypertensive rats compared with 3.6 +/- 0.6% in controls (P less than 0.01) confirmed also by histologic morphometry. H+ back-diffusion was 402 +/- 40 microEq/h in portal hypertensive rats and 217 +/- 30 microEq/h in controls (P less than 0.01). We conclude taurocholate induced gastric mucosal injury is enhanced by portal hypertension. Greater H+ back-diffusion in portal hypertensive rats suggests increased mucosal permeability contributed by submucosal edema. We confirm quantitatively in an experimental model that portal hypertension predisposes to gastric mucosal injury.