PHENYL RADICAL FORMATION BY OXYHEMOGLOBIN FROM PHENYLHYDRAZINE IN VIVO

氧合血红蛋白与苯肼的反应已收到 几十年来备受关注。这种兴趣的基础是 从苯肼和肼类药物诱导的能力 溶血性贫血。从体外电子获得的大量证据 自旋共振(ESR)实验表明这些事件与自由基有关 导致红细胞溶血。然而，在这份报告之前，没有 证实体内自由基形成的ESR证据已经被证实 呈上了。我们已经成功地利用电子自旋共振检测到了 灌胃给药大鼠血液中的自由基加合物 苯肼，然后在腹膜内注射自旋陷阱 5，5-二甲基-L-N-氧化物(DMPO)。一系列研究的结果 巯基试剂和C-13标记苯肼的实验研究 美国将这一DMPO自由基加合物指定为捕获 血红蛋白衍生的硫基自由基。除了苯肼， 肼类药物异烟肼、异丙肼、苯乙肼和肼 都进行了检查。在这四种药物中，只有苯乙肼和异丙肼能够 诱导DMPO/Hb硫基自由基加合物的形成 活体，而只有苯乙肼和肼丙嗪能够形成这种加合物 在试管中。我们能够减少体内异丙肼诱导的加合物 大鼠经双对硝基苯磷酸盐预处理后形成 芳酰胺酶抑制剂。我们的研究结果支持伊普尼扎德是 在肝脏中被分解成更活跃的代谢物，很可能 异丙肼，随后被释放到血液中。 DMPO/血红蛋白硫基自由基的形成不限于联氨， 但当过氧化氢或芳香族羟胺与 氧合血红蛋白。该物种可能是体内自由基损伤的指示物 到红血球。

The reaction of oxyhemoglobin with phenylhydrazine has received considerable attention for many decades. The basis for this interest stems from the ability of phenylhydrazine and hydrazine-based drugs to induce hemolytic anemia. Considerable evidence obtained from in vitro electron spin resonance (ESR) experiments implicates free radicals in the events leading to red blood cell hemolysis. However, until this report, no corroborating ESR evidence for in vivo free radical formation has been presented. We have successfully employed ESR to detect the formation of a radical adduct in the blood of rats which received an intragastric dose of phenylhydrazine followed by an intraperitoneal injection of the spin trap 5,5-dimethyl-l-pyrroline N-oxide (DMPO). The results of a series of experiments with sulfhydryl reagents and C-13-labelled phenylhydrazine led us to assign this DMPO radical adduct to the trapping of a hemoglobin-derived thiyl free radical. In addition to phenylhydrazine the hydrazine-based drugs isoniazid, iproniazid, phenelzine, and hydralazine were examined. Of the four drugs, only phenelzine and iproniazid were able to induce the formation of the DMPO/hemoglobin thiyl free radical adduct in vivo, whereas only phenelzine and hydralazine were able to form this adduct in vitro. We were able to decrease the in vivo iproniazid-induced adduct formation by pretreating the rats with bis-para-nitrophenylphosphate, an arylamidase inhibitor. Our results support the idea that iproniazid is hydrolyzed in the liver to a more reactive metabolite, most likely isopropylhydrazine, which is subsequently released into the blood stream. DMPO/hemoglobin thiyl free radical formation is not limited to hydrazines, but forms when either hydroperoxides or aromatic hydroxylamines react with oxyhemoglobin. This species may be in vivo indicator of free radical damage to red blood cells.