Benga G, Ionescu M, Popescu O, Pop V I
Mol Pharmacol. 1983 May;23(3):771-8.
ESR spectra of erythrocyte membranes labeled with a maleimide spin label (MSL) show two types of label environment: a weakly immobilized component and a strongly immobilized component. Chlorpromazine (CPZ) markedly altered the spectra: at pH 8.0, 3 mM CPZ reduced the amplitude of the spectrum by 40%, and the weakly immobilized component was almost completely removed. In order to clarify the mechanisms of these spectral changes the protein release from erythrocyte membranes induced by CPZ has been followed. CPZ had a weak solubilizing effect on erythrocyte membranes: less than 1% of the membrane protein was released, mainly Band 6. By comparison with the protein release induced by low-salt treatment it was found that the "detergent-like" property of CPZ cannot explain the alterations in the ESR spectra. The nature of the spectral changes induced by CPZ was different from that of changes induced by lowering the pH to 4.5; correlated with other data this shows that changes in organization or conformation of membrane protein cannot explain the CPZ-induced alterations in the ESR spectra. These spectral changes appeared to be due to the reduction by CPZ of the nitroxide free radical. This was documented by the marked reduction of spin concentration of the labeled ghosts in the presence of CPZ resulting in a decrease in amplitude of the ESR spectrum of MSL-labeled erythrocyte ghosts induced by CPZ. The reduction by CPZ of the nitroxide free radical was compared with that induced by ascorbate. It was found that CPZ preferentially reduces the mobile component of the ESR spectrum of MSL-labeled ghosts. The action of CPZ in reducing free radicals may have consequences for patients receiving long-term treatment with phenothiazine derivatives.
用马来酰亚胺自旋标记物（MSL）标记的红细胞膜的电子自旋共振（ESR）光谱显示出两种标记环境：一种是弱固定化成分，另一种是强固定化成分。氯丙嗪（CPZ）显著改变了光谱：在pH 8.0时，3 mM CPZ使光谱幅度降低了40%，并且弱固定化成分几乎完全消失。为了阐明这些光谱变化的机制，对CPZ诱导的红细胞膜蛋白释放进行了跟踪研究。CPZ对红细胞膜有微弱的增溶作用：释放的膜蛋白不到1%，主要是带6蛋白。通过与低盐处理诱导的蛋白释放进行比较，发现CPZ的“去污剂样”性质无法解释ESR光谱的变化。CPZ诱导的光谱变化的性质与将pH降至4.5所诱导的变化不同；与其他数据相关联，这表明膜蛋白的组织或构象变化无法解释CPZ诱导的ESR光谱变化。这些光谱变化似乎是由于CPZ对氮氧自由基的还原作用。这一点通过在CPZ存在下标记红细胞影的自旋浓度显著降低得到证明，导致CPZ诱导的MSL标记红细胞影的ESR光谱幅度下降。将CPZ对氮氧自由基的还原作用与抗坏血酸诱导的还原作用进行了比较。发现CPZ优先还原MSL标记红细胞影的ESR光谱中的可移动成分。CPZ在还原自由基方面的作用可能对接受吩噻嗪衍生物长期治疗的患者产生影响。
