Pro-oxidant 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 triggers lipid peroxidation. In sharp contrast with the tert-butylhydroperoxide-induced lipid peroxidation, the ultraviolet-A-induced lipid peroxidation is inhibited by treating cells with diethyldithiocarbamate. Diethyldithiocarbamate decreases superoxide dismutase activity and, to a lesser extent, the total glutathione level. Catalase and glutathione 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 peroxidation may thus be associated with superoxide dismutase inhibition. Membrane damage revealed by neutral red uptake is not prevented by diethyldithiocarbamate.