Dong Zeng-Xiang, Zhao Xin, Gu Dong-Fang, Shi Yuan-Qi, Zhang Jia, Hu Xing-Xia, Hu Mei-Qin, Yang Bao-Feng, Li Bao-Xin
Department of Pharmacology, Harbin Medical University, Harbin.
Cell Physiol Biochem. 2012;29(3-4):431-42. doi: 10.1159/000338497. Epub 2012 Apr 3.
Liensinine and neferine, a kind of isoquinoline alkaloid, can antagonize the ventricular arrhythmias. The human ether-a-go-go-related gene (hERG) is involved in repolarization of cardiac action potential. We investigated the effects of liensinine and neferine on the biophysical properties of hERG channel and the underlying structure-activity relationships. The effects of liensinine and neferine were examined on the hERG channels in the stable transfected HEK293 cells using a whole-cell patch clamp technique, western blot analysis and immunofluorescence experiment. The pharmacokinetics and tissue distribution determination of liensinine and neferine in rats were determined by a validated RP-HPLC method. Liensinine and neferine induced decrease of current amplitude in dose-dependent. Liensinine reduced hERG tail current from 70.3±6.3 pA/pF in control group to 56.7±2.8 pA/pF in the 1 μM group, 53.0±2.3 pA/pF (3 μM) and 17.8±0.7 pA/pF (30 μM); the corresponding current densities of neferine-treated cells were 41.9±3.1 pA/pF, 32.3±3.1 pA/pF and 16.2±0.6 pA/pF, respectively. Neferine had binding affinity for the open and inactivated state of hERG channel, liensinine only bound to the open state. The inhibitory effects of liensinine and neferine on hERG current were attenuated in the F656V or Y652A mutant channels. Neferine distributed more quickly than liensinine in rats, which was found to be in higher concentration than liensinine. Both liensinine and neferine had no effect on the generation and expression of hERG channels. In conclusion, neferine is a more potent blocker of hERG channels than liensinine at low concentration (<10 μM), which may be due to higher hydrophobic nature of neferine compared with liensinine. Neferine may be safety even for long-term treatment as an antiarrhythmic drug.
莲心碱和甲基莲心碱，一种异喹啉生物碱，可拮抗室性心律失常。人醚 - 去极化相关基因（hERG）参与心脏动作电位的复极化过程。我们研究了莲心碱和甲基莲心碱对hERG通道生物物理特性及其潜在构效关系的影响。采用全细胞膜片钳技术、蛋白质免疫印迹分析和免疫荧光实验，检测莲心碱和甲基莲心碱对稳定转染的HEK293细胞中hERG通道的影响。通过经过验证的反相高效液相色谱法（RP - HPLC）测定莲心碱和甲基莲心碱在大鼠体内的药代动力学和组织分布。莲心碱和甲基莲心碱呈剂量依赖性地导致电流幅度降低。莲心碱使hERG尾电流从对照组的70.3±6.3 pA/pF降至1 μM组的56.7±2.8 pA/pF、3 μM组的53.0±2.3 pA/pF和30 μM组的17.8±0.7 pA/pF；甲基莲心碱处理细胞的相应电流密度分别为41.9±3.1 pA/pF、32.3±3.1 pA/pF和16.2±0.6 pA/pF。甲基莲心碱对hERG通道的开放和失活状态具有结合亲和力，莲心碱仅与开放状态结合。在F656V或Y652A突变通道中，莲心碱和甲基莲心碱对hERG电流的抑制作用减弱。甲基莲心碱在大鼠体内的分布比莲心碱更快，且发现其浓度高于莲心碱。莲心碱和甲基莲心碱对hERG通道的产生和表达均无影响。总之，在低浓度（<10 μM）下，甲基莲心碱比莲心碱是更有效的hERG通道阻滞剂，这可能是由于甲基莲心碱与莲心碱相比具有更高的疏水性。作为一种抗心律失常药物，甲基莲心碱即使长期治疗可能也是安全的。
