Effects of two benzimidazoles as proton pump inhibitors on water immersion stress-induced gastric ulcers in rats.

This study was designed to clarify effects of proton pump inhibitors, E-3810(2-([4-(3-methoxypropoxy)-3methylpyridine-2-yl]methyl- sulfinyl)-1H-benzimidazol sodium salt) and omeprazole (CAS 73590-58-6), on water immersion stress-induced gastric ulcers in relation to mucosal prostaglandins (PGs) and leukotrienes (LTs). Mucosal PGs were measured by high performance liquid chromatography (HPLC). In untreated rats, 4 kinds of PGs, i.e., 6-keto-PGF1 alpha, PGF2 alpha, PGE2 and PGD2 were detected in gastric mucosa, but no LTs were detected. Water immersion stress for 6 h caused severe hemorrhagic lesions in the fundic portion and, concomitantly, significant decreases in mucosal PG levels. On the other hand, LTC4 and LTD4 were detected after 6 h stress treatment, though LTB4 and LTE4 were not detected throughout the experiments. Peptide-LT (the sum of LTC4 and LTD4) levels were 23.5 +/- 3.2 ng/g tissue 6 h after water immersion stress. Administration of 20 mg/kg of E-3810 or 20 mg/kg of omeprazole mitigated gastric lesions and increases in the mucosal peptide-LT levels, but dit not improve the decrease in mucosal PGs.