COMPARISON OF OXIDIZED LOW-DENSITY-LIPOPROTEIN TOXICITY ON EA.HY-926 CELLS AND HUMAN VEIN ENDOTHELIAL-CELLS - INFLUENCE OF ANTIOXIDANT SYSTEMS

We compared the susceptibility to oxidized LDL cytotoxicity of primary human umbilical vein endothelial cells (HUVEC) and EA.hy 926 cells. E A.hy 926 endothelial cells were more susceptible than HUVEC. To determ ine the basis of this difference, we evaluated the enzymatic antioxida nt machinery in the two cell types. The antioxidant enzyme activities of superoxide dismutase, catalase and glutathione peroxidase were sign ificantly lower in EA.hy cells than in HUVEC: 54%, 71% and 8% of the H UVEC enzyme activities respectively. Pre-incubation of the EA.hy 926 e ndothelial cells with glutathione peroxidase (100 IU/ml) inhibited the cytotoxic effect of oxidized LDL. Superoxide dismutase (300 or 600 IU /ml) and catalase (300 or 600 IU/ml) had no effect. Compared to HUVEC, the higher susceptibility of EA.hy 926 cells to oxidized LDL-induced injury may be associated with lower antioxidant defences, in particula r with lower glutathione peroxidase activity which is known to elimina te lipid hydroperoxides and thereby to prevent the formation of damagi ng peroxyl radical intermediates.