Experimental study of the etiology of paraquat lung *
The actual mechanism which paraquat damages the lung is unknown, and effective treatment has not yet been established. In this study, levels in activated oxygen in the bronchoalveolar lavage (BAL) fluid of paraquat-treated rats were measured using 2-methyl-6-(p-methoxyphenyl) -3, 7-dihydroimidazo (1,2-alpha) pyrazin-3-one (MCLA), a chemiluminescent probe. Paraquet-treated rats were divided into three groups; a high exposure group (120 mg/kg ip.), a moderate exposure group (60 mg/kg ip.), and a low exposure group (30 mg/kg ip.). The results of arterial blood gas analysis, and hematological findings, and pathological findings were also considered. Result showed that the activated oxygen significantly increased in every group, and that these increases were completely suppressed with superoxide dismutase (SOD). In the low exposure group in particular, a significant increase was noticed on day 6 after exposure. Such a finding has never been made before. Pathologically, polymorpho-nuclear leukocytes (PMNs) infilitrated the pulmonary alveolar interstitium and appeared in BAL fluid simultaneously with the increase in activated oxygen. These results indicate that superoxide anion plays a significant role in the formation of paraquat lung, especially in low exposure groups. Superoxide anion continued to participate in the formation of paraquat lung for at least one week. Considering the pathological findings, the suppression of PMNs function for at least a week after exposure would be necessary for the effective treatment of paraquat lung. (Accepted on October 25, 2000) Kawasaki Igakkaishi 27(1): 31-40, 2001
