CHANGES OF THE ACTIVITIES OF SUPEROXIDE-DISMUTASE AFTER EXPOSURE TO THE FUME OF HEAVY-METALS AND THE SIGNIFICANCE OF ZINC IN THE TISSUE

Pathological changes induced by Cd aerosol [an industrial pollutant] had features common to the changes evoked by oxidants. Female rats were exposed to fumes of Pb, Sb, Zn and Cd (15-100 nmol/m3). One hour after termination of exposure, superoxide dismutase (SOD) activity in erythrocytes of the exposed rats was lower by 15-40%. SOD activity of lung lavage fluid was also lower by 20-35% at the 2nd day after exposure. The inverse values of SOD activity (l/SOD) in erythrocytes and of lung lavage fluid were proportional to the molar exposure level adjusted by the particle size (Dixon plot), irrespective of the difference of the exposed substance. The ratio of dry weight to wet weight of the lung was 4.3-26% lower than the control value on the later period after exposure. With heavy metal exposure, uptake of the exposed metal was proportional to the endogenous Zn concentration, which correlated well with changes of SOD in the lung and erythrocytes. Cd decreased the Zn concentration after exposure.