Role of polymorphonuclear leukocytes and oxygen-derived free radicals in chronic gastric lesion induced by acetic acid in rat

This study examined the role of oxygen derived free radicals, the potential involvement of neutrophils and the possible mucosal vascular permeability changes involved in the pathogenesis and evolution of gastric mucosal lesions induced by acetic acid in the rat. Myeloperoxidase activity was assayed and used as an index of leukocyte infiltration. Application of acetic acid produced a significant increase in this activity 7 and 14 days after induction of chronic injury. Administration of hydroxyurea intraperitoneally was associated with a decrease in the severity of chronic ulceration and neutrophil infiltration into the gastric lesion, This effect was detectable enzymatically and microscopically. Orally administered allopurinol did not produce any beneficial effects on either the macroscopic and histological appearance or on vascular permeability. These results suggest that oxygen-derived free radicals may contribute to the formation and development of chronic lesions and that oxygen derived free radicals were generated from neutrophils, but not from the xanthine oxidase pathway. These inflammatory cells may, therefore, have a lesive role in the origin and course of acetic acid ulcer disease.