[Protective effect of magnesium on the damaged cultured endothelial cells induced by oxidized low density lipoprotein].

The protective effect of magnesium on endothelial cells induced by H2O2 and t-butyl hydroperoxide and the subsequent alterations of extracellular superoxide dismutase (EC-SOD) and cellular selenium-dependent and non-selenium-dependent GSH-Px are investigated in this study. Low density lipoproteins (LDLs) are isolated from poeled healthy human fresh sera by ultracentrifugation. Conjugate diene was measured for assessing the susceptibility of LDL to oxidation mediated by Cu2+. The extent of LDL modification is determined by measuring the formation of thiobarbituric acid reaction substances (TBARS). In addition, human umbilical vein endothelial cells are used to assess the effect of magnesium on damage induced by oxidized LDL (ox-LDL). The extent of cellular lipid peroxides is determined by measuring the formation of TBARS. Results show that (1) the presence of Mg2+ resulted in a protracted lag phase at doses of 0.3, 0.6, 1.2 and 2.4 mmol/L, as well as the presence of Mg2+ at doses of 0.3 and 0.6 mmol/L decreases the production of TBARS when LDL is oxidized by the addition of Cu2+; (2) the formation of TBARS is significantly reduced in the group of ox-LDL + Mg2+ at doses of 0.3, 0.6, 1.2 and 2.4 mmol/L. The activity of EC-SOD, GSH-Px with and without selenium in the group of ox-LDL + Mg2+ at all doses increases significantly compared with ox-LDL group. It is concluded that magnesium inhibits LDL oxidation mediated by Cu2+ and protected endothelial cells from lipid peroxidation and reinforces the activities of antioxidant enzymes.