Pascoe G A, Fariss M W, Olafsdottir K, Reed D J
Eur J Biochem. 1987 Jul 1;166(1):241-7. doi: 10.1111/j.1432-1033.1987.tb13508.x.
The depletion of cell calcium from isolated rat hepatocytes results in stimulated lipid peroxidation, loss of intracellular and mitochondrial GSH (reduced glutathione), and enhancement of both efflux and oxidation of GSH. These events are followed by cell injury and enhance the susceptibility of the cells to toxic chemicals. It is shown herein that an initial event in the generation of such injury is the depletion of cellular alpha-tocopherol. alpha-Tocopheryl succinate addition (25 microM) to the calcium-depleted cells markedly elevated the alpha-tocopherol content of the cells, inhibited the associated lipid peroxidation, and maintained intracellular GSH levels without affecting its efflux or redox status. This resulted in an enhanced formation of total glutathione after a 5-h incubation, which correlated with the alpha-tocopherol content of the cells, and was greater than that expected by a direct sparing action of vitamin E. Inhibition of hepatocyte glutathione biosynthesis by buthionine sulfoximine (0.5 mM) eliminated the enhancement of GSH formation by vitamin E. Analysis of endogenous and 35S-labelled precursors of glutathione biosynthesis by high-performance liquid chromatography demonstrated that the depletion of cellular alpha-tocopherol resulted in the efflux of glutathione precursors. It is concluded that cell injury associated with alpha-tocopherol depletion is partly the result of the efflux of glutathione precursors, and hence diminished biosynthesis and intracellular levels of GSH. These losses and resultant cell injury are preventable by maintenance of cellular alpha-tocopherol levels.
从分离的大鼠肝细胞中耗尽细胞内钙会导致脂质过氧化增强、细胞内和线粒体内谷胱甘肽（还原型谷胱甘肽）丧失，以及谷胱甘肽外排和氧化增加。这些事件随后会引发细胞损伤，并增强细胞对有毒化学物质的易感性。本文表明，这种损伤发生过程中的初始事件是细胞内α-生育酚的耗尽。向缺钙细胞中添加α-生育酚琥珀酸酯（25微摩尔）可显著提高细胞内α-生育酚含量，抑制相关的脂质过氧化，并维持细胞内谷胱甘肽水平，而不影响其外排或氧化还原状态。这导致在5小时孵育后总谷胱甘肽的形成增加，这与细胞内α-生育酚含量相关，且大于维生素E直接节约作用所预期的量。用丁硫氨酸亚砜胺（0.5毫摩尔）抑制肝细胞谷胱甘肽生物合成消除了维生素E对谷胱甘肽形成的增强作用。通过高效液相色谱法分析谷胱甘肽生物合成的内源性和35S标记前体表明，细胞内α-生育酚的耗尽导致谷胱甘肽前体的外排。得出的结论是，与α-生育酚耗尽相关的细胞损伤部分是谷胱甘肽前体外排的结果，因此谷胱甘肽的生物合成和细胞内水平降低。通过维持细胞内α-生育酚水平可预防这些损失及由此导致的细胞损伤。
