کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1911390 | 1046815 | 2006 | 6 صفحه PDF | دانلود رایگان |
One-electron oxidation of dopamine by ferricyanide generates a highly reactive free radical intermediate that inactivates the V-type H+-ATPase proton pump in catecholamine storage vesicles, i.e., the driving force in both the vesicular uptake and the storage of catecholamines, in a cell-free in vitro model system at pH 7.0. Electron paramagnetic resonance spectroscopy revealed that a radical with g = 2.0045, formed by this oxidation, was relatively long-lived (t1/2 obs = 79 s at pH 6.5 and 25°C). Experimental evidence is presented that the observed radical most likely represents dopamine semiquinone free radical, although an o-quinone free radical cannot be ruled out. Oxidation of noradrenaline and adrenaline by ferricyanide generated similar isotropic radicals, but of shorter half-lives (i.e., 43 and 5.3 s, respectively), and the efficacy of inactivation of the H+-ATPase correlated with the half-life of the respective catecholamine free radical (i.e., dopamine > noradrenaline ≫ adrenaline). Thus, the generation of relatively long-lived semiquinone free radicals, although at low concentrations, in dopaminergic and noradrenergic neurons may represent a common mechanism of cytotoxicity linked to neurodegeneration of the respective neurons related to Parkinson disease.
Journal: Free Radical Biology and Medicine - Volume 41, Issue 8, 15 October 2006, Pages 1266–1271