Reduction of paraquat toxicity by superoxide dismutase

The effect of intravenously administered superoxide dismutase on paraquat-treated rats kept either in air or an atmosphere of 90%–95% oxygen was investigated. Of those rats maintained in the oxygen-enriched atmosphere, 50% died within 30 hours whereas, 50 hours elapsed before 50% mortality was observed for the superoxide dismutase-treated rats. Those animals allowed to remain in air were more responsive to superoxide dismutase treatment. Of those animals for which paraquat was fatal, untreated rats showed 50% cumulative mortality within 35 hours after paraquat administration, whereas those rats treated with superoxide dismutase showed 50% mortality after 80 hours. Sections of lung tissue examined at low magnification indicated that the extensive alveolar and vascular damage caused by paraquat was ameliorated with the administration of superoxide dismutase. These findings may have particular relevance in the treatment of paraquat intoxication in humans.