Koshida H, Kotake Y
National Biomedical Center for Spin Trapping and Free Radicals, Oklahoma Medical Research Foundation, Oklahoma City.
Life Sci. 1994;55(6):463-70. doi: 10.1016/0024-3205(94)90058-2.
Recent findings have suggested that nitric oxide (NO) reacts with superoxide anion (O2-) to form a potential oxidant, peroxynitrite anion, which then decays to hydroxyl radical and nitrogen dioxide. In order to ascertain this hypothesis in human polymorphonuclear leukocytes (PMNs) which release both NO and O2-, we studied oxidation of L-cysteine (CYS) and bovine serum albumin (BSA) by PMNs and cell-free O2(-)-generating system of hypoxanthine (HX)-xanthine oxidase (XO) reaction. Oxidation of CYS by HX-XO was equally inhibited by superoxide dismutase (SOD) and catalase (CAT), and that of BSA by HX-XO was inhibited weakly by SOD and strongly by CAT. PMNs stimulated with phorbol 12-myristate 13-acetate increased the oxidation rates of CYS and BSA, and they were inhibited by SOD and CAT almost in a similar way to those by HX-XO. The NO synthase inhibitor, NG-monomethyl-L-arginine (NMMA), was confirmed to have an inhibitory effect on the inhibition of platelet aggregation by PMNs, and L-arginine (ARG) reversed this effect. However, pretreatment of PMNs with either of NMMA, or ARG, or both did not change the oxidation rates of CYS and BSA. We could not confirm the hypothesis at least in human PMNs that interaction of NO with O2- forms powerful oxidants to sulfhydryls of CYS and BSA. These results suggest that oxidation of sulfhydryls of CYS and BSA by PMNs is primarily dependent on reactive oxygen species, and is not modified by NO production.
最近的研究结果表明，一氧化氮（NO）与超氧阴离子（O2-）反应形成一种潜在的氧化剂——过氧亚硝酸盐阴离子，然后它会分解为羟基自由基和二氧化氮。为了在释放NO和O2-的人类多形核白细胞（PMN）中验证这一假设，我们研究了PMN以及次黄嘌呤（HX）-黄嘌呤氧化酶（XO）反应的无细胞O2(-)生成系统对L-半胱氨酸（CYS）和牛血清白蛋白（BSA）的氧化作用。HX-XO对CYS的氧化受到超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的同等抑制，而HX-XO对BSA的氧化受到SOD的微弱抑制和CAT的强烈抑制。用佛波醇12-肉豆蔻酸酯13-乙酸酯刺激的PMN提高了CYS和BSA的氧化速率，并且它们受到SOD和CAT的抑制，其方式与HX-XO的抑制方式几乎相似。NO合酶抑制剂NG-单甲基-L-精氨酸（NMMA）被证实对PMN抑制血小板聚集具有抑制作用，而L-精氨酸（ARG）可逆转这种作用。然而，用NMMA、ARG或两者对PMN进行预处理均未改变CYS和BSA的氧化速率。至少在人类PMN中，我们无法证实NO与O2-相互作用形成对CYS和BSA巯基有强大氧化作用的氧化剂这一假设。这些结果表明，PMN对CYS和BSA巯基的氧化主要依赖于活性氧，并且不受NO生成的影响。
