EFFECT OF LEAD ON OXYGEN FREE-RADICAL METABOLISM - INHIBITION OF SUPEROXIDE-DISMUTASE ACTIVITY

The effect of lead ion on superoxide dismutase activity (SOD) and on t he rate of spontaneous 6 hydroxydopamine oxidation was studied in vitr o, since lead is a well known established toxin effecting the central nervous system, bone marrow, bone and kidney and is thus a major publi c health problem throughout the world. Lead strongly inhibits SOD acti vity in vitro in an SOD 6 hydrodopamine system in direct proportion to its concentration in a range between 0.167 mug/ml and 0.67 mug/ml in the final reaction mixture. This inhibition of SOD activity was more p ronounced with 6 hydroxydopamine concentrations of 0.066 mg/ml of reac tion mixture than with a concentration of 0.033 mg/ml of reaction mixt ure. Lead had no effect on oxidation of 6 hydroxydopamine in vitro. Le ad is thus shown to be capable in vitro of inhibiting SOD activity and thus reducing oxygen free radical (OFR) destruction. This may contrib ute to cell membrane damage and be one of the mechanisms of lead toxic ity on many organs.