Richard M J, Guiraud P, Leccia M T, Beani J C, Favier A
Laboratoire de Biochimie C, Centre Hospitalier Régional Universitaire A. Michallon, Grenoble, France.
Biol Trace Elem Res. 1993 May-Jun;37(2-3):187-99. doi: 10.1007/BF02783794.
In purified system zinc has been shown to have an antioxidant role. Its effects on the resistance of cultured cells towards oxidative stress in vitro were examined. Diploid human skin fibroblasts were grown for 21 d in culture media (RPMI 1640 containing 15% fetal calf serum) added with different zinc (Zn) concentrations (100, 125, and 150 microM as Zinc chlorur ZnCl2). In comparison, cell controls were grown in standard culture media (6.5 microM Zn). The intracellular zinc levels of treated fibroblasts increased from 3- to 7-fold (2330 +/- 120 ng/mg protein in 150-microM Zn-treated cells versus 331 +/- 21 ng/mg protein in control cells). The intracellular copper increased 3- fold whereas the iron content slightly but not significantly decreased. The index of basal lipid peroxidation measured as thiobarbituric acid reactants (TBARs) of zinc-supplemented cells was lower than that of non zinc supplemented controls (0.89 mumol/g protein in 150 microM Zn-treated cells versus 1.59 mumol/g protein in controls). At these high doses of zinc, fibroblasts expressed lower antioxidant metalloenzymes activities. Diminished TBARs in Zn treated cells tends to support that Zn acts protectively against free radical mediated damage. However when the cells were challenged with extracellular oxidant stresses mediated by hypoxanthine/xanthine oxidase or hydrogen peroxide (H2O2), an increased toxicity in Zn-supplemented cells was observed. When we applied an intracellular oxidative stress as UV-B or UV-A radiation, Zn-treated fibroblasts were more resistant than cells grown in normal medium. If Zn has shown antioxidant effect in some in vitro or in vivo systems our observations clearly demonstrate that this role is not mediated by antioxidant metalloenzymes.
在纯化系统中，锌已被证明具有抗氧化作用。研究了其对体外培养细胞抵抗氧化应激能力的影响。将二倍体人皮肤成纤维细胞在添加不同锌（Zn）浓度（100、125和150微摩尔，以氯化锌ZnCl2形式）的培养基（含15%胎牛血清的RPMI 1640）中培养21天。相比之下，细胞对照组在标准培养基（6.5微摩尔锌）中培养。经处理的成纤维细胞的细胞内锌水平增加了3至7倍（150微摩尔锌处理的细胞中为2330±120纳克/毫克蛋白质，而对照细胞中为331±21纳克/毫克蛋白质）。细胞内铜增加了3倍，而铁含量略有下降但不显著。以硫代巴比妥酸反应物（TBARs）衡量的补充锌细胞的基础脂质过氧化指数低于未补充锌的对照组（150微摩尔锌处理的细胞中为0.89微摩尔/克蛋白质，而对照组中为1.59微摩尔/克蛋白质）。在这些高剂量锌的情况下，成纤维细胞表达的抗氧化金属酶活性较低。锌处理细胞中TBARs的减少倾向于支持锌对自由基介导的损伤具有保护作用。然而，当细胞受到次黄嘌呤/黄嘌呤氧化酶或过氧化氢（H2O2）介导的细胞外氧化应激挑战时，观察到补充锌的细胞毒性增加。当我们施加紫外线B或紫外线A辐射作为细胞内氧化应激时，锌处理的成纤维细胞比在正常培养基中生长的细胞更具抗性。如果锌在某些体外或体内系统中显示出抗氧化作用，我们的观察结果清楚地表明，这种作用不是由抗氧化金属酶介导的。
