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本文旨在研究槲皮素填充的卵磷脂脂质体(quercetin-filled phosphatidylcholine liposomes,PCL-Q)对非致死性全身电离辐射处理的大鼠胸主动脉平滑肌细胞(smooth muscle cells,SMCs)上的大电导钙离子依赖性钾通道(large conductance Ca2+-dependent K+channels,BKCa)的作用。我们使用膜片钳技术,观察到去极化阶跃脉冲刺激的SMCs上出现外向K+电流,该电流对paxilline(BKCa的一种特异性抑制剂)敏感,因此认为该电流主体为BKCa电流。相对正常对照大鼠,辐照处理大鼠SMCs的BKCa电流幅度明显减小。这种通道抑制效应在辐照后第9天表现显著,且在整个30天的实验期间是逐渐增强的。辐照处理大鼠的SMCs的血管舒张能力可能因此而减弱。在本实验中,PCL-Q有效地恢复了辐照后SMCs的BKCa功能。而PCL-Q的组分,单一的槲皮素或“空白”的脂质体(PCL)恢复BKCa功能的能力较二者的组合体有明显的减弱。上述结果表明,PCL-Q能恢复辐照处理后SMCs的BKCa正常功能。PCL-Q的保护能力可能来源于其抗氧化、修复质膜和抑制蛋白激酶C的作用。由此可见,这种脂胶囊化的黄酮类化合物——PCL-Q是一种在放射性事故急救和放疗副作用防治方面颇具前景的药物。
The aim of this study was to investigate the effect of quercetin-filled phosphatidylcholine liposomes (PCL-Q) on smooth muscle cells (SMCs) in rat thoracic aorta smooth muscle cells treated with non-lethal systemic ionizing radiation. Large conductance calcium-dependent potassium channels (large conductance Ca2+-dependent K+ channels, BKCa) role. Using the patch-clamp technique, we observed outward K+ currents on SMCs stimulated by a depolarizing step pulse. This current is sensitive to paxilline, a specific inhibitor of BKCa, and is therefore considered to be the BKCa current. Compared with the normal control rats, the BKCa current amplitude of irradiated SMCs was significantly reduced. This channel inhibitory effect was significant on the 9th day after irradiation and gradually increased during the entire 30-day experiment period. The vasodilation of SMCs in irradiated rats may be reduced. In this experiment, PCL-Q effectively restored the BKCa function of irradiated SMCs. However, the ability of PCL-Q components, single quercetin or “blank” liposomes (PCL) to restore BKCa function was significantly reduced compared to the combination of the two. The above results indicate that PCL-Q can restore normal BKCa function of SMCs after irradiation. The protective ability of PCL-Q may derive from its anti-oxidation, repair of plasma membrane and inhibition of protein kinase C. Thus, this lipid-encapsulated flavonoid, PCL-Q, is a promising drug in the prevention and treatment of radioactive accidents and side effects of radiotherapy.