Kadiiska M B, Hanna P M, Mason R P
National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Toxicol Appl Pharmacol. 1993 Dec;123(2):187-92. doi: 10.1006/taap.1993.1236.
The electron spin resonance (ESR) spin trapping technique was employed to study the role of Cu(II) in the generation of hydroxyl radical during paraquat (PQ2+) intoxication in rats. A secondary radical trapping technique was used for the detection of hydroxyl radical generated in vivo during copper-mediated PQ2+ toxicity. According to this technique (Burkitt and Mason, Proc. Natl. Acad. Sci. USA 88, 8440-8444, 1991), the hydroxyl radical generated reacts with dimethyl sulfoxide (DMSO) in vivo to form the methyl radical, which is then spin trapped by phenyl-N-tert-butylnitrone (PBN). The relatively stable methyl radical adduct of PBN was detected in the bile of rats 2 hr after treatment with simultaneous doses of CuSO4, PQ2+, PBN, and DMSO, whereas no radical adducts were detected in the absence of administered PQ2+. Bile samples were collected into Cu(I)- and Fe(II)-stabilizing agents in order to prevent the occurrence of radical adducts generated ex vivo in bile during its collection. The analysis of radical adducts excreted via the biliary route provide strong ESR evidence for the generation of the hydroxyl radical as a result of the known futile enzymatic redox cycling of PQ2+, with copper playing an essential mediatory role. No radical adducts were detected when either CuSO4 or PQ2+ was excluded. From a different perspective, in vivo copper-dependent hydroxyl radical generation could be said to be promoted by PQ2+. This is the first report of ESR evidence for this synergetic hydroxyl radical generation by copper and PQ2+ in a whole animal.
采用电子自旋共振（ESR）自旋捕获技术研究铜离子（Cu(II)）在百草枯（PQ2+）诱导的大鼠中毒过程中羟自由基生成中的作用。采用二级自由基捕获技术检测铜介导的PQ2+毒性过程中体内生成的羟自由基。根据该技术（Burkitt和Mason，《美国国家科学院院刊》88，8440 - 8444，1991），生成的羟自由基在体内与二甲基亚砜（DMSO）反应形成甲基自由基，然后被苯基 - N - 叔丁基硝酮（PBN）自旋捕获。在用硫酸铜、PQ2+、PBN和DMSO同时给药处理2小时后，在大鼠胆汁中检测到相对稳定的PBN甲基自由基加合物，而在未给予PQ2+时未检测到自由基加合物。将胆汁样本收集到含有Cu(I)和Fe(II)稳定剂的容器中，以防止在胆汁收集过程中体外生成自由基加合物。通过胆汁途径排泄的自由基加合物分析为PQ2+已知的无效酶促氧化还原循环产生羟自由基提供了有力的ESR证据，其中铜起重要的介导作用。当排除硫酸铜或PQ2+时未检测到自由基加合物。从不同角度来看，可以说PQ2+促进了体内铜依赖性羟自由基的生成。这是关于铜和PQ2+在完整动物中协同产生羟自由基的ESR证据的首次报道。
