Acquired long QT syndromes and torsade de points often occur with underlying hypokalemia andbradycardia. With its fast inactivation property, the rapid activating component (Ikr) of the delayed rectifierpotassium curr...Acquired long QT syndromes and torsade de points often occur with underlying hypokalemia andbradycardia. With its fast inactivation property, the rapid activating component (Ikr) of the delayed rectifierpotassium current (IK) plays an important role in maintaining normal QT intervals. In this study, we evaluated the effects of different extracellular potassium ([K].) on the fast inactivation current of Ikr in guinea pigventricular myocytes. The results showed that [K]. had strong effects on the fast inactivation current ; thelower [K].(1, 3 mmol/L) significantly decreased the inactivation outward current (P<0. 05); while higher[K]. (8, 10, 20 mmol/L) slightly increased the inactivation current (P>0. 05). These results may be of greatclinical significance. The lower [K]. decreased Ikr inactivation current, which may help to explain why acquired long QT syndromes and torsade de points often occur in the lower [K]. The correction of hypokalemia can increase the inactivation current, therefore, it is critical in the treatment of acquired long QTsyndromes and torsade de points.展开更多
目的探讨药物致尖端扭转型室性心动过速(Tdp)的发生机制。方法建立冠状动脉灌注的犬左室心肌楔形组织块模型,同步记录左心室内膜、中层、外膜心肌细胞的动作电位及跨壁心电图,观察不同浓度D-Sotalol对动作电位时间(APD)、QT间期、跨壁...目的探讨药物致尖端扭转型室性心动过速(Tdp)的发生机制。方法建立冠状动脉灌注的犬左室心肌楔形组织块模型,同步记录左心室内膜、中层、外膜心肌细胞的动作电位及跨壁心电图,观察不同浓度D-Sotalol对动作电位时间(APD)、QT间期、跨壁复极离散度(TDR)、早期后除极(EAD)及Tdp发生的影响。结果浓度为0~100μmol/L的D-Sotalol呈剂量依赖性地延长各层细胞APD,尤以中层细胞最为显著(P<0.05),因而增加TDR;D-Sotalol在中层细胞可诱发EAD,触发室性早博并形成跨壁折返导致Tdp。结论 D-Sotalol在中层细胞诱发EAD、R on T室性早博是其致Tdp的始动因子,在TDR增加的基础上形成跨室壁折返是Tdp得以维持的关键。展开更多
人类心肌电生理过程存在着性别差异。长QT综合征时,女性发生尖端扭转性室性心动过速(torsade de pointes,TdP)的风险明显大于男性。越来越多的证据提示性激素可能影响重要的心肌复极电流,从而影响心肌复极的性别差异。该文综述长QT综合...人类心肌电生理过程存在着性别差异。长QT综合征时,女性发生尖端扭转性室性心动过速(torsade de pointes,TdP)的风险明显大于男性。越来越多的证据提示性激素可能影响重要的心肌复极电流,从而影响心肌复极的性别差异。该文综述长QT综合征TdP发生率的性别差异以及人类和动物心肌电生理的性别差异及其与性激素的相关研究,以阐明性激素在药物诱发心律失常性别差异中的作用及其机制。展开更多
文摘Acquired long QT syndromes and torsade de points often occur with underlying hypokalemia andbradycardia. With its fast inactivation property, the rapid activating component (Ikr) of the delayed rectifierpotassium current (IK) plays an important role in maintaining normal QT intervals. In this study, we evaluated the effects of different extracellular potassium ([K].) on the fast inactivation current of Ikr in guinea pigventricular myocytes. The results showed that [K]. had strong effects on the fast inactivation current ; thelower [K].(1, 3 mmol/L) significantly decreased the inactivation outward current (P<0. 05); while higher[K]. (8, 10, 20 mmol/L) slightly increased the inactivation current (P>0. 05). These results may be of greatclinical significance. The lower [K]. decreased Ikr inactivation current, which may help to explain why acquired long QT syndromes and torsade de points often occur in the lower [K]. The correction of hypokalemia can increase the inactivation current, therefore, it is critical in the treatment of acquired long QTsyndromes and torsade de points.
文摘目的探讨药物致尖端扭转型室性心动过速(Tdp)的发生机制。方法建立冠状动脉灌注的犬左室心肌楔形组织块模型,同步记录左心室内膜、中层、外膜心肌细胞的动作电位及跨壁心电图,观察不同浓度D-Sotalol对动作电位时间(APD)、QT间期、跨壁复极离散度(TDR)、早期后除极(EAD)及Tdp发生的影响。结果浓度为0~100μmol/L的D-Sotalol呈剂量依赖性地延长各层细胞APD,尤以中层细胞最为显著(P<0.05),因而增加TDR;D-Sotalol在中层细胞可诱发EAD,触发室性早博并形成跨壁折返导致Tdp。结论 D-Sotalol在中层细胞诱发EAD、R on T室性早博是其致Tdp的始动因子,在TDR增加的基础上形成跨室壁折返是Tdp得以维持的关键。
文摘人类心肌电生理过程存在着性别差异。长QT综合征时,女性发生尖端扭转性室性心动过速(torsade de pointes,TdP)的风险明显大于男性。越来越多的证据提示性激素可能影响重要的心肌复极电流,从而影响心肌复极的性别差异。该文综述长QT综合征TdP发生率的性别差异以及人类和动物心肌电生理的性别差异及其与性激素的相关研究,以阐明性激素在药物诱发心律失常性别差异中的作用及其机制。