Radi R, Beckman J S, Bush K M, Freeman B A
Department of Anesthesiology, University of Alabama, Birmingham 35233.
Arch Biochem Biophys. 1991 Aug 1;288(2):481-7. doi: 10.1016/0003-9861(91)90224-7.
Endothelial cells, macrophages, neutrophils, and neuronal cells generate superoxide (O2-) and nitric oxide (.NO) which can combine to form peroxynitrite anion (ONOO-). Peroxynitrite, known to oxidize sulfhydryls and to yield products indicative of hydroxyl radical (.OH) reaction with deoxyribose and dimethyl sulfoxide, is shown herein to induce membrane lipid peroxidation. Peroxynitrite addition to soybean phosphatidylcholine liposomes resulted in malondialdehyde and conjugated diene formation, as well as oxygen consumption. Lipid peroxidation was greater at acidic and neutral pH, with no significant lipid peroxidation occurring above pH 9.5. Addition of ferrous (Fe+2) or ferric (Fe+3) iron did not enhance lipid peroxide formation over that attributable to peroxynitrite alone. Diethylenetetraminepentacetic acid (DTPA) or iron removal from solutions by ion-exchange chromatography decreased conjugated diene formation by 25-50%. Iron did not play an essential role in initiating lipid peroxidation, since DTPA and iron depletion of reaction systems were only partially inhibitory. In contrast, desferrioxamine had an even greater concentration-dependent inhibitory effect, completely abolishing lipid peroxidation at 200 microM. The strong inhibitory effect of desferrioxamine on lipid peroxidation was due to direct reaction with peroxynitrous acid in addition to iron chelation. We conclude that the conjugate acid of peroxynitrite, peroxynitrous acid (ONOOH), and/or its decomposition products, i.e., .OH and nitrogen dioxide (.NO2), initiate lipid peroxidation without the requirement of iron. These observations demonstrate a potential mechanism contributing to O2-(-)and .NO-mediated cytotoxicity.
内皮细胞、巨噬细胞、中性粒细胞和神经元细胞会产生超氧化物（O2-）和一氧化氮（·NO），它们可结合形成过氧亚硝酸盐阴离子（ONOO-）。过氧亚硝酸盐已知可氧化巯基，并产生与脱氧核糖和二甲基亚砜发生羟基自由基（·OH）反应的产物，本文显示其可诱导膜脂质过氧化。向大豆磷脂酰胆碱脂质体中添加过氧亚硝酸盐会导致丙二醛和共轭二烯形成，以及耗氧。在酸性和中性pH条件下脂质过氧化程度更高，在pH 9.5以上未发生明显的脂质过氧化。添加亚铁（Fe+2）或铁（Fe+3）并不会比单独由过氧亚硝酸盐引起的脂质过氧化增加更多。二乙烯三胺五乙酸（DTPA）或通过离子交换色谱法从溶液中去除铁会使共轭二烯形成减少25 - 50%。铁在引发脂质过氧化过程中并不起关键作用，因为反应体系中DTPA和铁的消耗只是部分具有抑制作用。相比之下，去铁胺具有更强的浓度依赖性抑制作用，在200 microM时完全消除脂质过氧化。去铁胺对脂质过氧化的强烈抑制作用是由于除了铁螯合作用外，还与过氧亚硝酸直接反应。我们得出结论，过氧亚硝酸盐的共轭酸、过氧亚硝酸（ONOOH）和/或其分解产物，即·OH和二氧化氮（·NO2），可引发脂质过氧化，无需铁的参与。这些观察结果证明了一种导致O2-(-)和·NO介导的细胞毒性的潜在机制。
