Zeng H, Spencer N Y, Hogg N
Biophysics Research Institute and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Am J Physiol Heart Circ Physiol. 2001 Jul;281(1):H432-9. doi: 10.1152/ajpheart.2001.281.1.H432.
S-nitrosoglutathione (GSNO) is an inhibitor of platelet aggregation and has also been shown to protect the ischemic heart from reperfusion-mediated injury. Although GSNO is often used in cell culture as a source of nitric oxide, the mechanisms of GSNO metabolism are not well established. We show here that GSNO decomposition by bovine aortic endothelial cells has an absolute dependence on the presence of cystine in the cell culture medium. In addition, GSNO decay is inhibited by diethyl maleate, an intracellular glutathione scavenger, but not by buthionine sulfoximine, a glutathione synthesis inhibitor. This indicates that thiols in general, rather than specifically glutathione, are the major factors that influence GSNO decay. Only 40% of the nitroso group of GSNO could be recovered as nitrite/nitrate, suggesting that the primary route of GSNO decay is reductive and that nitric oxide is only a minor product of GSNO decay. We conclude that the intracellular thiol pool causes the reduction of extracellular disulfides to thiols, which then directly reduce GSNO.
S-亚硝基谷胱甘肽（GSNO）是血小板聚集的抑制剂，并且已被证明还能保护缺血心脏免受再灌注介导的损伤。尽管GSNO在细胞培养中常被用作一氧化氮的来源，但其代谢机制尚未完全明确。我们在此表明，牛主动脉内皮细胞对GSNO的分解绝对依赖于细胞培养基中胱氨酸的存在。此外，细胞内谷胱甘肽清除剂马来酸二乙酯可抑制GSNO的降解，但谷胱甘肽合成抑制剂丁硫氨酸亚砜胺则无此作用。这表明一般的硫醇而非特定的谷胱甘肽是影响GSNO降解的主要因素。GSNO中只有40%的亚硝基基团能以亚硝酸盐/硝酸盐的形式回收，这表明GSNO降解的主要途径是还原性的，且一氧化氮只是GSNO降解的次要产物。我们得出结论，细胞内硫醇池导致细胞外二硫键还原为硫醇，然后硫醇直接还原GSNO。
