We evaluated the damage to the gastric epithelium produced by local ischemia-reperfusion (IR) with or without luminal perfusion with 0.1 N HCl. Local gastric ischemia was induced by clamping the left gastric artery. Use of radioactive microsphere technique revealed a significant reduction in blood flow induced only in the corpus (67% reduction). Because no measurable gross lesion was observed in this model, the blood-to-lumen clearance of 51Cr-labeled EDTA (51Cr-EDTA) served as an index of epithelial damage. In the absence of exogenous acid, the histological damage was minimum and could not be quantified. However, a significant increase in 51Cr-EDTA clearance was observed shortly after reperfusion in a manner that depended on the duration of ischemia. This increase in clearance reached a maximum approximately 10 min after reperfusion and returned rapidly toward control levels within 40-50 min after reperfusion. In the presence of exogenous acid, EDTA clearance increased significantly during ischemia, increased further during reperfusion, and did not recover for at least 60 min after reperfusion. The acid infused after reperfusion (no acid before reperfusion) did not significantly aggravate the mucosal damage that followed reperfusion. However, the acid infused before reperfusion (no acid after reperfusion) showed an effect on EDTA clearance similar to that induced by continuous acid perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)