ox-LDL和生理浓度抗坏血酸对人脐静脉内皮细胞eNOS活性的影响

EFFECTS OF OXIDIZED LOW DENSITY LIPOPROTEIN AND L-ASCORBIC ACID OF PHYSIOLOGICAL CONCENTRATION ON CULTURED HUMAN UMBILICAL ENDOTHELIAL CELLS

目的 探讨氧化低密度脂蛋白（ox-LDL）和生理浓度抗坏血酸对乙酰胆碱诱导的内皮型一氧化氮合酶（eNOS）活性及一氧化氮（NO）生成量的影响及其可能机制。方法 在培养人脐静脉内皮细胞（HUVECs）中加入25、50、100mg／L的ox-LDL和生理浓度抗坏血酸作用24h后，测定NO生成量、eNOS活性及细胞内谷胱甘肽（GSH）含量。结果 ox-LDL以剂量依赖方式降低乙酰胆碱诱发的eNOS活性，减少NO的生成；生理浓度抗坏血酸改善eNOS活性，同时增加NO生成，差异均有显著性（F=50．075、48．400，q=3．773～19．998，P〈0．05、0．01）。而细胞内GSH的含量在ox-LDL（50mg／L）组与抗坏血酸组无明显差异。结论 ox-LDL通过降低eNOS活性而减少NO的生成。生理浓度抗坏血酸通过直接影响eNOS活性而抑制该效应，此与其抗氧化作用无关。

Objective To investigate the effects and its mechanism of oxidized low-density lipoprotein （ox-LDL） and L-ascorbic acid of physiological concentration on endothelial nitric oxide synthase （eNOS） activity and nitric oxide （NO） production induced by acetylcholine in human umbilical vein endothelial ceils. Methods The endotheliai ceils were incubated with L-ascorbic acid （ 100 μmol/L） and subsequently exposed to different concentrations of ox-LDL from 0 to 100 mg/L for 24 h at 37 ℃. NO production, eNOS activity, and level of glutathione were measured. Results ox-LDL decreased eNOS activity and NO production in a dose-dependent manner. L-ascorbic acid at physiological concentration enhanced eNOS activity and NO production, with significant differences between the two groups （F=50. 075, 48. 400;q=3. 773-19. 998; P〈0. 05,0.01）. However, level of glutathione in cell lysate was not changed between ox-LDL （50 mg/L） group and L-ascorbic acid group. Conclusion ox-LDL may decrease NO production via attenuating NOS activity in HUVECs. L-ascorbic acid at physiological concentration ameliorates eNOS activity without antioxidation.