目的应用全细胞膜片钳技术观察抗毒瘾药物伊博格碱对异源转染Human ether-a-go-go-related(HERG)基因编码通道电流的影响。方法在人胚肾293细胞上转染野生型HERG基因,采用全细胞膜片钳技术记录HERG电流,观察99.5%纯度和95%纯度不同浓度1...目的应用全细胞膜片钳技术观察抗毒瘾药物伊博格碱对异源转染Human ether-a-go-go-related(HERG)基因编码通道电流的影响。方法在人胚肾293细胞上转染野生型HERG基因,采用全细胞膜片钳技术记录HERG电流,观察99.5%纯度和95%纯度不同浓度1、5、10、50μmol/L伊博格碱对HERG电流阻滞的作用以及99.5%纯度5μmol/L伊博格碱对通道动力学的影响。结果 99.5%纯度和95%纯度的伊博格碱阻滞HERG电流的半数最大抑制浓度(IC50)无显著差异(P>0.05),分别为(4.09±0.69)μmol/L和(3.53±0.16)μmol/L。99.5%纯度的伊博格碱5μmol/L可逆性抑制HERG电流,使HERG通道电流电压依赖性的半激活电压左移[(-3.1±2.0)m V vs(-15.2±2.1)m V,P<0.01],半失活电压左移[(-45±3)m V vs(-59±3)m V,P<0.01];在所有测试电压下加快HERG通道失活;在测试电压-40 m V时,延缓HERG通道从失活中恢复[(891±103)ms vs(1 831±334)ms,P<0.05]。结论伊博格碱阻滞HERG通道电流,主要作用在HERG通道的失活状态。展开更多
Background The rapidly activating delayed rectifier potassium current （/Kr）, whose pore-forming alpha subunit is encoded by the human ether-a-go-go-related gene （hERG）, is a key contributor to the third phase of a...Background The rapidly activating delayed rectifier potassium current （/Kr）, whose pore-forming alpha subunit is encoded by the human ether-a-go-go-related gene （hERG）, is a key contributor to the third phase of action potential repolarization. The aim of this study was to investigate the effect and mechanism of arecoline hydrobromide induced inhibition of hERG K^＋ current （/hERG）. Methods Transient transfection of hERG channel cDNA plasmid pcDNA3.1 into the cultured HEK293 cells was performed using Lipofectamine. A standard whole-cell patch-clamp technique was used to record the /hI=RG before and after the exposure to arecoline. Results Arecoline decreased the amplitude and the density of the /bERG in a concentration-dependent manner （IC5o=9.55 μmol/L）. At test potential of ＋60 mV, the magnitude of lhERG tail at test pulse of -40 mV was reduced from （151.7±6.2） pA/pF to （84.4±7.6） pA/pF （P 〈0.01, n=20） and the magnitude of IhERG tail at test pulse of -110 mV was reduced from （-187.5±9.8） pA/pF to （-97.6±12.6） pA/pF （P 〈0.01, n=20）. The blockade of arecoline in the open and inactivated state was significant in a state-dependent manner. The maximal blockade was achieved in the inactivated state. Studies of gating mechanism showed that the steady-state activation curve of IhERG was significantly negatively shifted by arecoline. Time constants of activation were shortened. Steady-state inactivation curve and time constants of fast inactivation were not significantly affected by arecoline. Furthermore, the inhibition of IhERG by arecoline was characterized markedly by a frequency-dependent manner from 0.03 to 1.00 Hz pulse. Conclusion Arecoline could potently block IhERG in both frequency and state-dependent manner.展开更多
文摘目的应用全细胞膜片钳技术观察抗毒瘾药物伊博格碱对异源转染Human ether-a-go-go-related(HERG)基因编码通道电流的影响。方法在人胚肾293细胞上转染野生型HERG基因,采用全细胞膜片钳技术记录HERG电流,观察99.5%纯度和95%纯度不同浓度1、5、10、50μmol/L伊博格碱对HERG电流阻滞的作用以及99.5%纯度5μmol/L伊博格碱对通道动力学的影响。结果 99.5%纯度和95%纯度的伊博格碱阻滞HERG电流的半数最大抑制浓度(IC50)无显著差异(P>0.05),分别为(4.09±0.69)μmol/L和(3.53±0.16)μmol/L。99.5%纯度的伊博格碱5μmol/L可逆性抑制HERG电流,使HERG通道电流电压依赖性的半激活电压左移[(-3.1±2.0)m V vs(-15.2±2.1)m V,P<0.01],半失活电压左移[(-45±3)m V vs(-59±3)m V,P<0.01];在所有测试电压下加快HERG通道失活;在测试电压-40 m V时,延缓HERG通道从失活中恢复[(891±103)ms vs(1 831±334)ms,P<0.05]。结论伊博格碱阻滞HERG通道电流,主要作用在HERG通道的失活状态。
基金This study was supported by the grants from the National Natural Science Foundation of China （No. 81170177 and No. 30770901 ）.Acknowledgment： We would like to thank Prof. Priori, University of Pavia in Italy for generously providing the hERG plasmid.
文摘Background The rapidly activating delayed rectifier potassium current （/Kr）, whose pore-forming alpha subunit is encoded by the human ether-a-go-go-related gene （hERG）, is a key contributor to the third phase of action potential repolarization. The aim of this study was to investigate the effect and mechanism of arecoline hydrobromide induced inhibition of hERG K^＋ current （/hERG）. Methods Transient transfection of hERG channel cDNA plasmid pcDNA3.1 into the cultured HEK293 cells was performed using Lipofectamine. A standard whole-cell patch-clamp technique was used to record the /hI=RG before and after the exposure to arecoline. Results Arecoline decreased the amplitude and the density of the /bERG in a concentration-dependent manner （IC5o=9.55 μmol/L）. At test potential of ＋60 mV, the magnitude of lhERG tail at test pulse of -40 mV was reduced from （151.7±6.2） pA/pF to （84.4±7.6） pA/pF （P 〈0.01, n=20） and the magnitude of IhERG tail at test pulse of -110 mV was reduced from （-187.5±9.8） pA/pF to （-97.6±12.6） pA/pF （P 〈0.01, n=20）. The blockade of arecoline in the open and inactivated state was significant in a state-dependent manner. The maximal blockade was achieved in the inactivated state. Studies of gating mechanism showed that the steady-state activation curve of IhERG was significantly negatively shifted by arecoline. Time constants of activation were shortened. Steady-state inactivation curve and time constants of fast inactivation were not significantly affected by arecoline. Furthermore, the inhibition of IhERG by arecoline was characterized markedly by a frequency-dependent manner from 0.03 to 1.00 Hz pulse. Conclusion Arecoline could potently block IhERG in both frequency and state-dependent manner.
