Liu D, Ling X, Wen J, Liu J
Department of Neurology, University of Texas Medical Branch, Galveston, Texas 77555-0653, USA.
J Neurochem. 2000 Nov;75(5):2144-54. doi: 10.1046/j.1471-4159.2000.0752144.x.
To determine whether reactive nitrogen species contribute to secondary damage in CNS injury, the time courses of nitric oxide, peroxynitrite, and nitrotyrosine production were measured following impact injury to the rat spinal cord. The concentration of nitric oxide measured by a nitric oxide-selective electrode dramatically increased immediately following injury and then quickly declined. Nitro-L-arginine reduced nitric oxide production. The extracellular concentration of peroxynitrite, measured by perfusing tyrosine through a microdialysis fiber into the cord and quantifying nitrotyrosine in the microdialysates, significantly increased after injury to 3.5 times the basal level, and superoxide dismutase and nitro-L-arginine completely blocked peroxynitrite production. Tyrosine nitration examined immunohistochemically significantly increased at 12 and 24 h postinjury, but not in sham-control sections. Mn(III) tetrakis(4-benzoic acid)-porphyrin (a novel cell-permeable superoxide dismutase mimetic) and nitro-L-arginine significantly reduced the numbers of nitrotyrosine-positive cells. Protein-bound nitrotyrosine was significantly higher in the injured tissue than in the sham-operated controls. These results demonstrate that traumatic injury increases nitric oxide and peroxynitrite production, thereby nitrating tyrosine, including protein-bound tyrosine. Together with our previous report that trauma increases superoxide, our results suggest that reactive nitrogen species cause secondary damage by nitrating protein through the pathway superoxide + nitric oxide peroxynitrite protein nitration.
为了确定活性氮物质是否会导致中枢神经系统损伤中的继发性损伤，在大鼠脊髓受到撞击损伤后，测量了一氧化氮、过氧亚硝酸盐和硝基酪氨酸生成的时间进程。通过一氧化氮选择性电极测量的一氧化氮浓度在损伤后立即显著增加，然后迅速下降。硝基-L-精氨酸减少了一氧化氮的生成。通过将酪氨酸通过微透析纤维灌注到脊髓中并对微透析液中的硝基酪氨酸进行定量来测量的过氧亚硝酸盐的细胞外浓度在损伤后显著增加至基础水平的3.5倍，超氧化物歧化酶和硝基-L-精氨酸完全阻断了过氧亚硝酸盐的生成。免疫组织化学检测的酪氨酸硝化在损伤后12小时和24小时显著增加，但在假手术对照组切片中未增加。锰（III）四（4-苯甲酸）-卟啉（一种新型的可穿透细胞的超氧化物歧化酶模拟物）和硝基-L-精氨酸显著减少了硝基酪氨酸阳性细胞的数量。损伤组织中蛋白质结合的硝基酪氨酸显著高于假手术对照组。这些结果表明，创伤性损伤会增加一氧化氮和过氧亚硝酸盐的生成，从而使酪氨酸硝化，包括蛋白质结合的酪氨酸。连同我们之前关于创伤会增加超氧化物的报告，我们的结果表明，活性氮物质通过超氧化物 +一氧化氮→过氧亚硝酸盐→蛋白质硝化的途径使蛋白质硝化，从而导致继发性损伤。
