Comparative in vitro toxicity of cadmium and lead on redox cycling in typeII pneumocytes

Both cadmium and lead have pulmonary toxicity: cadmium can cause lung cance r, fibrosis and emphysema; lead can induce a moderate interstitial pulmonar y fibrosis. Both metals give rise to depletion of glutathione and depletion of the protein-bound sulfhydryl groups, and lead to the production of reac tive oxygen species. In the primary culture of type Il pneumocytes, which i s one of the most important cell groups from the aspect of glutathione meta bolism and thus redox balance, the effect of cadmium chloride and lead nitr ate upon the enzymes of the glutathione cycle, upon superoxide dismutase an d upon the structure of type II pneumocytes was examined. Depending on the concentration, cadmium inhibited each of these parameters, whereas lead nit rate significantly increased the activity of glutathione reductase while in hibiting other parameters. Both metals induced damage of the membranes of t ype II cells, depending on the concentration, although cadmium caused signi ficantly more damage than lead. The data obtained suggest that both substan ces cause an imbalance in the redox cycle and diversely affect the function and membrane structure of type II pneumocytes. Copyright (C) 2001 John Wil ey & Sons, Ltd.