Increases in endogenous antioxidant enzymes during asbestos inhalation in rats.

Although the pathogenesis of asbestos-induced pulmonary damage is still not completely understood, an important role has been attributed to active oxygen species. In the present paper we present results of a study investigating the effect of crocidolite asbestos inhalation on different lung antioxidant enzymes in rats. During the development of pulmonary fibrosis induced by crocidolite asbestos, lung superoxide dismutase, catalase and selenium-dependent glutathione peroxidase activities increased, indicating an adaptive response to increased pulmonary oxidant stress. However, this adaptive response obviously is not sufficient to protect the lung from asbestos-induced pulmonary damage. Considering the role of active oxygen species in both the fibrotic process and tumor promotion, it is hypothesized that antioxidants may also protect the lung from chronic asbestos-induced pulmonary damage such as bronchogenic carcinoma.