Le C T, Hollaar L, Van der Valk E J, Franken N A, Van Ravels F J, Wondergem J, Van der Laarse A
Department of Cardiology, University Hospital, Leiden, The Netherlands.
Eur Heart J. 1995 Apr;16(4):553-62. doi: 10.1093/oxfordjournals.eurheartj.a060950.
The primary defence mechanism of myocytes against peroxides and peroxide-derived peroxyl and alkoxyl radicals is the glutathione redox cycle. The purpose of the present study was to increase the turnover rate of this cycle by stimulating the glutathione peroxidase catalysed reaction (2GSH-->GSSG), the glutathione reductase catalysed reaction (GSSG-->2GSH), or both. Neonatal rat heart cell cultures were subjected to a standardized protocol of oxidative stress using 80 mumol.l-1 cumene hydroperoxide (CHPO) for 0-90 min. The consequences of this protocol were described in terms of cellular concentrations of GSH, GSSG, NADPH and ATP, formation of malondialdehyde (MDA), release of GSSG and of ATP catabolites, depression of contraction frequency, cellular calcium overload, and enzyme release. Trolox-C, an analogue of vitamin E, accelerated the glutathione peroxidase reaction leading to lowering of GSH concentration and the GSH/GSSG ratio, less MDA formation, diminished negative chronotropy, delayed calcium overload, and less enzyme release. Glucose was used to accelerate the glutathione reductase reaction by supplying NADPH, leading to higher GSH concentration and a higher GSH/GSSG ratio, less MDA formation, diminished negative chronotropy, unchanged development of calcium overload, and less enzyme release. As a full turn of the glutathione redox cycle involves both the peroxidase and the reductase reactions, the combination of Trolox-C and glucose was superior to either of the two alone: 90 min following addition of CHPO together with Trolox-C and glucose, the GSH concentration and the GSH/GSSG ratio were almost normal, MDA formation was extremely low, calcium overload was markedly delayed, and enzyme release hardly occurred at all. Cells remained beating in the observation period of 30 min. We conclude that the capacity of the glutathione redox cycle to withstand oxidative stress can be increased by stimulation of either the peroxidase reaction or the reductase reaction, and that optimal redox cycling is achieved by stimulation of both reactions.
心肌细胞抵御过氧化物以及过氧化物衍生的过氧自由基和烷氧自由基的主要防御机制是谷胱甘肽氧化还原循环。本研究的目的是通过刺激谷胱甘肽过氧化物酶催化的反应（2GSH→GSSG）、谷胱甘肽还原酶催化的反应（GSSG→2GSH）或两者来提高该循环的周转率。使用80μmol·L-1的氢过氧化异丙苯（CHPO）对新生大鼠心脏细胞培养物进行0至90分钟的标准化氧化应激实验方案。该方案的后果通过细胞内谷胱甘肽（GSH）、氧化型谷胱甘肽（GSSG）、还原型辅酶II（NADPH）和三磷酸腺苷（ATP）的浓度、丙二醛（MDA）的形成、GSSG和ATP分解代谢产物的释放、收缩频率降低、细胞钙超载以及酶释放来描述。维生素E类似物生育三烯酚（Trolox-C）加速了谷胱甘肽过氧化物酶反应，导致GSH浓度和GSH/GSSG比值降低，MDA形成减少，负性变时作用减弱，钙超载延迟，酶释放减少。葡萄糖通过提供NADPH来加速谷胱甘肽还原酶反应，导致GSH浓度升高和GSH/GSSG比值升高，MDA形成减少，负性变时作用减弱，钙超载发展不变，酶释放减少。由于谷胱甘肽氧化还原循环的完整一轮涉及过氧化物酶和还原酶反应，生育三烯酚（Trolox-C）和葡萄糖的组合优于单独使用两者中的任何一种：在加入CHPO以及生育三烯酚（Trolox-C）和葡萄糖90分钟后，GSH浓度和GSH/GSSG比值几乎正常，MDA形成极低，钙超载明显延迟，并且几乎完全没有酶释放。在30分钟的观察期内细胞仍在跳动。我们得出结论，通过刺激过氧化物酶反应或还原酶反应可以提高谷胱甘肽氧化还原循环抵御氧化应激的能力，并且通过刺激这两种反应可实现最佳的氧化还原循环。
