The portal hypertensive gastric mucosa: histologic, ultrastructural, and functional analysis after aspirin-induced damage.

We assessed macroscopic, histologic, ultrastructural, and functional features of aspirin-induced gastric mucosal injury in portal hypertensive and sham-operated rats. Portal hypertension was produced by staged portal vein ligation. Four hours after intragastric acidified aspirin administration, intraluminal pH in portal hypertensive rats was 6.6 +/- 0.2 and 4.3 +/- 0.5 in sham-operated controls (p less than 0.01). Gross mucosal damage was significantly greater in portal hypertensive rats compared with controls (18 +/- 2 versus 7 +/- 1% of total mucosal area). Histologic deep necrosis involved 22 +/- 2% of mucosal section lengths in portal hypertensive rats compared with 7 +/- 1% in sham-operated rats (p less than 0.01). In portal hypertensive rats, histologic and ultrastructural evaluation demonstrated capillary endothelial abnormalities, arterialization of submucosal veins, and markedly greater severity of microvascular damage than in sham-operated controls. Neutralized aspirin (pH, 7.0) did not produce any significant damage detectable grossly, histologically, or by transmission electron microscopy in portal hypertensive rats. We conclude that acid-dependent aspirin-induced gastric mucosal damage is significantly increased in portal hypertension.