Srivastava S, Dixit B L, Cai J, Sharma S, Hurst H E, Bhatnagar A, Srivastava S K
Division of Cardiology, University of Louisville, Louisville, KY, USA.
Free Radic Biol Med. 2000 Oct 1;29(7):642-51. doi: 10.1016/s0891-5849(00)00351-8.
Lipid peroxidation represents a significant source of erythrocyte dysfunction and aging. Because the toxicity of lipid peroxidation appears to be in part due to aldehydic end products, we examined, in rat erythrocytes, the metabolism of 4-hydroxy-trans-2-nonenal (HNE), one of the most abundant and toxic lipid-derived aldehydes. Packed erythrocytes, 0.1 ml, completely metabolized 20 nmoles of HNE in 20 min. The glutathione conjugate of HNE and 4-hydroxynonanoic acid (HNA) represented 70 and 25% of the total metabolism, respectively. Approximately 70% of the metabolites were extruded to the medium. Upon electrospray ionization mass spectrometry, the glutathione conjugate resolved into two distinct species corresponding to glutathionyl HNE (GS-HNE) and glutathionyl 1,4-dihydroxynonene (GS-DHN). The concentration of GS-DHN formed was twice that of GS-HNE. Inhibition of aldose reductase by sorbinil and tolrestat led to a selective decrease in the formation of GS-DHN, although the extent of HNE glutathiolation was unaffected. Inhibitors of aldehyde or alcohol dehydrogenase, i.e., cyanamide and 4-methyl pyrazole, had no effect on the formation of HNA and GS-DHN, indicating that these enzymes are not significant participants in the erythrocyte HNE metabolism. Thus, oxidation to HNA, conjugation with glutathione, and further reduction of the conjugate by aldose reductase appear to be the major pathways of HNE metabolism in erythrocytes. These pathways may be critical determinants of erythrocyte toxicity due to lipid peroxidation-derived aldehydes.
脂质过氧化是红细胞功能障碍和衰老的一个重要来源。由于脂质过氧化的毒性似乎部分归因于醛类终产物，我们在大鼠红细胞中研究了4-羟基反式-2-壬烯醛（HNE）的代谢，HNE是最丰富且毒性最强的脂质衍生醛类之一。0.1 ml的压积红细胞在20分钟内可完全代谢20纳摩尔的HNE。HNE与谷胱甘肽的结合物以及4-羟基壬酸（HNA）分别占总代谢量的70%和25%。大约70%的代谢产物被排到培养基中。在电喷雾电离质谱分析中，谷胱甘肽结合物分解为两种不同的物质，分别对应谷胱甘肽基HNE（GS-HNE）和谷胱甘肽基1,4-二羟基壬烯（GS-DHN）。形成的GS-DHN的浓度是GS-HNE的两倍。索比尼尔和托瑞司他对醛糖还原酶的抑制导致GS-DHN的形成选择性减少，尽管HNE与谷胱甘肽的结合程度未受影响。醛脱氢酶或醇脱氢酶的抑制剂，即氰胺和4-甲基吡唑，对HNA和GS-DHN的形成没有影响，这表明这些酶在红细胞HNE代谢中不是重要参与者。因此，氧化为HNA、与谷胱甘肽结合以及醛糖还原酶对结合物的进一步还原似乎是红细胞中HNE代谢的主要途径。这些途径可能是脂质过氧化衍生醛类导致红细胞毒性的关键决定因素。
