Ascorbate- and dehydroascorbic acid-mediated reduction of free radicals in the human erythrocyte.
Ascorbate- and dehydroascorbic acid-mediated reduction of free radicals in the human erythrocyte.
复制标题
DOI：
10.1016/s0021-9258(18)49905-x
复制
发表时间：
1991-02
期刊：
影响因子：
--
通讯作者：
R. Mehlhorn
中科院分区：
文献类型：
--
作者：
R. Mehlhorn
以一氧化氮为持久性自由基模型，研究了抗坏血酸对人红细胞的抗氧化作用。结论是：1）在硫醇存在下衍生自脱氢抗坏血酸（DHA）的抗坏血酸盐和其它还原剂是氮氧自由基的唯一重要还原剂，2）谷胱甘肽和DHA通过不能被抗坏血酸氧化酶抑制的过程还原氮氧自由基，3）在膜可渗透的阳离子氮氧自由基如N，N-二甲基氨基-克里思存在下，通过彻底洗涤可以耗尽红细胞中的抗坏血酸，4）抗坏血酸耗竭的细胞不还原氮氧自由基;然而，当细胞与DHA一起孵育时，氮氧还原恢复，5）在抗坏血酸耗尽的DHA处理的细胞中氮氧还原明显快于DHA和谷胱甘肽的缓冲溶液，6）相对于细胞内抗坏血酸库，几当量的氮氧还原，7）即使当大多数细胞内抗坏血酸盐被氧化时，也观察到持续的氮氧自由基减少，8）叔丁基过氧化氢处理的细胞中氧自由基的自旋捕获随着抗坏血酸盐耗尽而加速，并且随着抗坏血酸盐加载而抑制，9）通过分析膜可渗透的阳离子氮氧化物的初始还原速率，可以定量完整细胞内的抗坏血酸盐，和10）DHA刺激的阳离子氮氧化物的还原在葡萄糖-6-磷酸脱氢酶缺陷的红细胞中比在正常红细胞中更慢且更不广泛。
Nitroxides were used as models of persistent free radicals to study the antioxidant function of ascorbic acid in the human erythrocyte. It was concluded that: 1) ascorbate and other reductant(s) derived from dehydroascorbic acid (DHA) in the presence of thiols are the only significant reducing agents for nitroxides, 2) glutathione and DHA reduce nitroxides by a process that cannot be inhibited by ascorbic acid oxidase, 3) erythrocytes can be depleted of ascorbic acid by exhaustive washing in the presence of membrane-permeable cationic nitroxides such as N,N-dimethylamino-Tempo, 4) ascorbate-depleted cells do not reduce nitroxides; however, nitroxide reduction is restored when the cells are incubated with DHA, 5) reduction of nitroxides in ascorbate-depleted, DHA-treated cells is significantly faster than in buffered solutions of DHA and glutathione, 6) several equivalents of nitroxide are reduced relative to the intracellular ascorbate pool, 7) sustained nitroxide reduction is observed even when most of the intracellular ascorbate is oxidized, 8) spin trapping of oxyradicals in tert-butyl hydroperoxide-treated cells is accelerated with ascorbate depletion and inhibited with ascorbate loading, 9) ascorbate can be quantified within intact cells by analyzing the initial reduction rates of membrane-permeable cationic nitroxides, and 10) DHA-stimulated reduction of cationic nitroxides is slower and less extensive in erythrocytes deficient in glucose-6-phosphate dehydrogenase than in normal erythrocytes.