Ulker S, McMaster D, McKeown P P, Bayraktutan U
Department of Medicine, Institute of Clinical Science Block B, Queen's University Belfast, Belfast BT12 6BJ, UK.
Diabetes Obes Metab. 2004 Nov;6(6):442-51. doi: 10.1111/j.1462-8902.2004.00443.x.
Vitamins C and E have protective features in many disease states associated with enhanced oxidative stress. The aim of this study was to investigate whether vitamin(s) C and/or E modulate hyperglycaemia-induced oxidative stress by regulating enzymatic activities of prooxidant, i.e. NAD(P)H oxidase and/or antioxidant enzymes, namely endothelial nitric oxide synthase (eNOS), superoxide dismutase, catalase and glutathione peroxidase, using coronary microvascular endothelial cells (CMEC).
CMEC were cultured under normal (5.5 mM) or high glucose (22 mM) concentrations for 7 days. The enzyme activities were determined by specific assays. The levels of O(2) (-) and nitrite were measured by cytochrome c reduction and Griess assays respectively.
Hyperglycaemia did not alter eNOS activity or overall nitrite generation, an index of NO production. However, it increased NAD(P)H oxidase and antioxidant enzyme activities (p < 0.05). Specific inhibitors of NAD(P)H oxidase, i.e. phenylarsine oxide (0.1-3 microm) and 4-(2-aminoethyl)benzenesulfonyl fluoride (5-100 microm) and vitamins C and E (0.1-1 microm) significantly reduced prooxidant and antioxidant enzyme activities in CMEC exposed to hyperglycaemia (p < 0.01). The differences in enzyme activities were independent of increases in osmolarity generated by high glucose levels as investigated by using equimolar concentrations of mannitol in parallel experiments.
Vitamins C and E may protect CMEC against hyperglycaemia-induced oxidative stress by concomitantly regulating prooxidant and antioxidant enzyme activities.
维生素C和E在许多与氧化应激增强相关的疾病状态中具有保护作用。本研究的目的是使用冠状动脉微血管内皮细胞（CMEC），研究维生素C和/或E是否通过调节促氧化剂（即NAD(P)H氧化酶）和/或抗氧化酶（即内皮型一氧化氮合酶（eNOS）、超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶）的酶活性来调节高血糖诱导的氧化应激。
将CMEC在正常（5.5 mM）或高糖（22 mM）浓度下培养7天。通过特定测定法测定酶活性。分别通过细胞色素c还原法和格里斯法测量O(2) (-)和亚硝酸盐的水平。
高血糖并未改变eNOS活性或总体亚硝酸盐生成（NO产生的指标）。然而，它增加了NAD(P)H氧化酶和抗氧化酶的活性（p < 0.05）。NAD(P)H氧化酶的特异性抑制剂，即苯胂氧化物（0.1 - 3 microm）和4-(2-氨基乙基)苯磺酰氟（5 - 100 microm）以及维生素C和E（0.1 - 1 microm）显著降低了暴露于高血糖的CMEC中的促氧化剂和抗氧化酶活性（p < 0.01）。如在平行实验中使用等摩尔浓度的甘露醇所研究的，酶活性的差异与高糖水平产生的渗透压增加无关。
维生素C和E可能通过同时调节促氧化剂和抗氧化酶活性来保护CMEC免受高血糖诱导的氧化应激。
