Aspirin can inhibit gastric mucosal cyclo-oxygenase without causing lesions in rat.
Dose-response relationships between aspirin-induced cyclo-oxygenase inhibition and gastric mucosal injury were studied in rats. Oral or parenteral aspirin, 25 mg/kg, inhibited prostaglandin generation by 87%-95% at 1, 3, and 6 h with no lesion formation. Aspirin, 100 mg/kg, inhibited prostaglandin generation by 95%-98% at 1, 3, and 6 h, but lesions were observed only when aspirin was given orally. Three-hour pretreatment with intraperitoneal aspirin, 12.5 mg/kg, did not enhance the mucosal injury caused by 10 mM acidified taurocholate, although prostaglandin generation was inhibited by 80%. Pretreatment with 25 mg/kg aspirin inhibited prostaglandin generation by 89% and was associated with significant mucosal injury by acidified taurocholate. We conclude that aspirin-induced 95% inhibition of gastric mucosal cyclo-oxygenase is not, by itself, sufficient to produce lesions and inhibition by greater than 80% is required to predispose the gastric mucosa to injury by otherwise mild irritants.
D000284:Administration, Oral; D000818:Animals; D001241:Aspirin / Q000008:administration & dosage / Q000494:pharmacology*; D016861:Cyclooxygenase Inhibitors; D004305:Dose-Response Relationship, Drug; D011464:Epoprostenol / Q000096:biosynthesis; D005753:Gastric Mucosa / Q000187:drug effects* / Q000201:enzymology; D007274:Injections, Intraperitoneal; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013656:Taurocholic Acid / Q000494:pharmacology
D016861:Cyclooxygenase Inhibitors; D013656:Taurocholic Acid; D011464:Epoprostenol; D001241:Aspirin