小颗粒致密低密度脂蛋白氧化特性及对血管内皮细胞脂质过氧化的影响

了解小颗粒致密低密度脂蛋白中抗氧化维生素含量、氧化特性 ,探讨其对血管内皮细胞脂质过氧化的影响。采用二次密度梯度超速离心的方法分离制备小颗粒致密低密度脂蛋白 ,高压液相色谱测定其抗氧化物质维生素A、E和 β 胡萝卜素 ;连续监测小颗粒致密低密度脂蛋白在 2 34nm的吸光度以测定其氧化敏感曲线 ;在血管内皮培养液中分别加入不同浓度的小颗粒致密低密度脂蛋白 ,培养后测定培养液丙二醛的浓度。实验成功分离小颗粒致密低密度脂蛋白 ,与大而轻低密度脂蛋白相比 ,维生素A、E和 β 胡萝卜素等抗氧化物质及总抗氧化能力明显减少 ,只有大而轻低密度脂蛋白的 6 5 %、39%和 2 4 % ,故小颗粒致密低密度脂蛋白氧化的延迟时间只有大而轻低密度脂蛋白的 37.5 % ,但硫代巴比妥酸反应物质值及氧化速率分别是大而轻低密度脂蛋白的 1 .7倍和 1 .2 8倍 ;培养液中丙二醛含量随加入脂蛋白的浓度和作用时间而增高 ,2 4h时小颗粒致密低密度脂蛋白 5 0mg组、1 0 0mg组、1 5 0mg组与相同剂量大而轻低密度脂蛋白组比较丙二醛显著增高 (P <0 .0 5 )。上述结果提示 :小颗粒致密低密度脂蛋白中抗氧化物质及抗氧化能力下降 ,氧化敏感性增高 ,并促进内皮细胞过氧化损伤

The Oxidative Property of Small Dense Low Density Lipoprotein and Its Effect on Lipid Peroxidation of Vascular Endothelial Cell

Aim To clarify the content of antioxidant vitamins and oxidative property in small dense low density lipoprotein (sLDL) and to explore the role of small dense low density lipoprotein in lipid peroxidation of vascular endothelial cell. Methods Small dense low density lipoprotein was obtained by two sequential gradient ultra centrifugation and observed by negative staining electron microscopy; the content antioxidant vitamins such as vitamin A,alpha tocopherol (vitamin E) and beta carotene were measured by high performance liquid chromatography (HPLC). Continuously monitor small dense Low density lipoprotein susceptibility curve at absorbance 234 nm mediated by Cu 2+ . After exposure to small dense low density lipoprotein in vascular endothelial cell the malondialdehyde was measured. Results The small dense low density lipoprotein was isolated successfully. Compared with large buoyant low density lipoprotein, vitamin A,alpha tocopherol (vitamin E) and beta carotene and total antioxidant capacity of sLDL was 65%, 39% and 24% respectively lower and its lag phase was 37.5% lower, but its thiobarbituric acid reacting substances (TBARS) was 1.7 higher, while the the propgagtion phase was 1.28 longer. The malondialdehyde (MDA) content in culture media of 50 mg, 100 mg and 150 mg sLDL groups in 24 hour were significantly higher than those of the same dosage of large buoyant Low density lipoprotein (P<0.05). Conclusion The results suggest sLDL has strong effects on pathogenesis of atherosclerosis which may be related to decreased antioxidant content and antioxidation property and increased susceptibility to oxidation, as well as promoting peroxidation injure of vascular endothelial cell.