View article

Background: Excessive production of nitric oxide, characteristic of inflamed states, may have deleterious effects through its facile conversion (in the presence of O₂) to peroxynitrite, which promotes lipid and sulfhydryl oxidation. This study assessed the effect of peroxynitrite on the rat colon. Methods: Peroxynitrite was administered intrarectally to rats. One, 3,7, and 21 days after treatment, a distal colonic segment was isolated and tissue was obtained for histological evaluation and determination of myeloperoxidase activity and NO_x, and eicosanoids generation. Results: Within 24 hours, the exposed segment was edematous and congested with occasional hemorrhagic mucosal ulceration. On day 7, the lumen was narrow; at day 21, there were signs of stenosis. Histological analysis showed transmucosal necrosis, acute inflammation, and exudative edema 24 hours after treatment. Surface re-epithelization and …