镁对人体低密度脂蛋白氧化修饰的影响

目的 :　观察镁对人体低密度脂蛋白 (LDL)氧化修饰的影响。方法 :　一次性密度梯度超速离心法制备人天然 LDL,共轭二烯法检测 Mg2 +对 Cu2 +介导的 LDL氧化反应敏感性的影响 ,硫代巴比妥酸反应物 (TBARS)法检测 Mg2 +对 Cu2 +和内皮细胞介导的 LDL氧化修饰程度的影响。结果 :　 1 .LDL+Cu2 + +Mg2 +各剂量组 LDL氧化反应潜伏期较 LDL+Cu2 +组明显延长 ;2 .LDL+Cu2 + +0 .3mmol/L Mg2 +组和 LDL+Cu2 + +0 .6mmol/L Mg2 +组 TBARS低于 LDL+Cu2 + 组 ,P<0 .0 1 ;3.在内皮细胞介导的 LDL氧化体系中 ,补 Mg2 + 各剂量组 TBARS低于空白对照组 ,LDL+Mg2 +各剂量组 TBARS低于 LDL组 ,差异均具有显著性 (P<0 .0 5)。结论 :　在一定实验条件下 Mg2 +可阻断 LDL的氧化反应

EFFECT OF MAGNESIUM SUPPLEMENTATION ON OXIDATIVE MODIFICATION OF HUMAN LOW DENSITY LIPOPROTEIN

Objective: The effects of magnesium on the oxidation of low density lipoprotein (LDL) were systematically investigated by two different oxidation systems. Methods: LDLs were isolated from pooled healthy human fresh sera by ultracentrifugation. Oxidation of LDL was induced by adding Cu 2+ or co-cultured with cultured human umbilical vein endothelial cells. Conjugate diene was measured to assess the susceptibility of LDL to oxidation. The extent of LDL modification was determined by measuring the formation of thiobarbituric acid reaction substances (TBARS). Results: (1)The presence of Mg 2+ resulted in a protracted lag phase at doses of 0.3 mmol/L, 0.6 mmol/L, 1.2 mmol/L, and 2.4 mmol/L, as well as decreased production of TBARS when LDL was oxidized by the addition of Cu 2+ , at doses of 0.3 mmol/L and 0.6 mmol/L Mg 2+ .(2)Treatment of LDL with Mg 2+ (0.3 mmol/L, 0.6 mmol/L, 1.2 mmol/L, and 2.4 mmol/L) reduced the production of TBARS during endothelial cell-mediated LDL oxidation, P< 0.05 . Conclusion: Magnesium protects LDL from oxidation.