PROOXIDANT ROLE OF SUPEROXIDE-DISMUTASE IN ULTRAVIOLET-A-INDUCED LIPID-PEROXIDATION IN CULTURED NORMAL HUMAN SKIN FIBROBLASTS

Exposure of cultured normal human skin fibroblasts to ultraviolet A tr iggers lipid peroxidation, In sharp contrast with the tert-butylhydrop eroxide-induced lipid peroxidation, the ultraviolet-A-induced lipid pe roxidation is inhibited by treating cells with diethyldithiocarbamate. Diethyldithiocarbamate decreases superoxide dismutase activity and, t o a lesser extent, the total glutathione level. Catalase and glutathio ne peroxidase, however, are unaffected. The decrease in the superoxide dismutase activity parallels an inhibition of H2O2 formation in both irradiated and unirradiated cells. The protection against lipid peroxi dation may thus be associated with superoxide dismutase inhibition. Me mbrane damage revealed by neutral red uptake is not prevented by dieth yldithiocarbamate.