EFFECTS OF ALPHA-TOCOPHEROL ON ANTIOXIDANT ENZYME-ACTIVITY IN HUMAN FIBROBLAST-CULTURES

The activities of superoxide dismutase (SOD), glutathione peroxidase ( GPx) and catalase (Cat) were determined in human fibroblast cultures a t four concentrations of exogenous alpha-tocopherol: 0.2, 2.5, 10 and 50 mug/ml of culture medium, or without alpha-tocopherol. Relationship s between alpha-tocopherol levels and the activities of SOD and GPx we re identified. The cellular alpha-tocopherol level correlated with GPx activity (p less-than-or-equal-to 0.01) and inversely correlated with SOD activity (p less-than-or-equal-to 0.003), but only when alpha-toc opherol was added to the culture medium. The variations in the cellula r GPx/SOD ratio depended on the level of cellular alpha-tocopherol (p less-than-or-equal-to 0.001). Furthermore, there was a strong inverse correlation between SOD and GPx activity (p less-than-or-equal-to 0.00 01). Cat activity did not correlate either with cellular alpha-tocophe rol concentration, or with SOD or GPx activity. These results underlin e the complex interplay between alpha-tocopherol and other antioxidant systems in human fibroblast cultures.