Paraquat toxicity and pulmonary superoxide dismutase: an enzymic deficiency of lung microsomes.

Paraquat stimulates the microsomal generation of superoxide radical, O2-, and hydrogen peroxide, H2O2. The detoxification of these two oxidants is accomplished by superoxide dismutase (SOD) and catalase, respectively. SOD activity could not be detected in lung microsomes but was found in microsomes of both kidney and liver. This deficiency may be involved in the pulmonary specificity of paraquat.