Suzuki-Nishimura T, Swartz H M
Dartmouth Medical School, Hanover, NH 03755-3863.
Free Radic Biol Med. 1994 Nov;17(5):473-9. doi: 10.1016/0891-5849(94)90174-0.
There is a need to understand the metabolism of nitroxides because of their usefulness in measurements in living cells of complex phenomena, such as biophysical properties, redox metabolism, and the concentration of oxygen at specific sites. As part of a systematic study of the metabolism of nitroxides in cells, the authors studied Chinese hamster ovary (CHO) cells and mouse macrophage tumor (M5076) cells, using a set of lipophilic nitroxides based on 5 doxyl stearate: the free acid, the methyl ester of the acid, and a phosphatidylcholine with two doxyl stearates esterified to the glycerol. The rates of metabolism of these nitroxides under anoxia differed significantly as a function of both the type of cell and the type of nitroxide. The rates of reduction of the three lipophilic nitroxides depended on their localization. The rates of reduction were first order for all three lipophilic nitroxides, and the only products detected were the respective hydroxylamines. Effects of freeze-thawing and incubation temperature differed in the two cell lines. The authors conclude that the metabolism of nitroxides in different cell lines can be quite different. This may be especially important in understanding studies using nitroxides in living cells, functional organs, and in vivo.
由于氮氧化物在测量活细胞中的复杂现象（如生物物理特性、氧化还原代谢以及特定部位的氧气浓度）方面具有实用性，因此有必要了解其代谢情况。作为对细胞中氮氧化物代谢进行系统研究的一部分，作者使用了一组基于5-硬脂酰氧基硬脂酸酯的亲脂性氮氧化物，研究了中国仓鼠卵巢（CHO）细胞和小鼠巨噬细胞瘤（M5076）细胞：游离酸、该酸的甲酯以及一种甘油上酯化有两个5-硬脂酰氧基硬脂酸酯的磷脂酰胆碱。在缺氧条件下，这些氮氧化物的代谢速率因细胞类型和氮氧化物类型的不同而存在显著差异。三种亲脂性氮氧化物的还原速率取决于它们的定位。所有三种亲脂性氮氧化物的还原速率均为一级反应，且检测到的唯一产物是各自的羟胺。冻融和孵育温度对这两种细胞系的影响有所不同。作者得出结论，不同细胞系中氮氧化物的代谢可能存在很大差异。这在理解使用氮氧化物进行的活细胞、功能器官及体内研究时可能尤为重要。
