The properties of the inward-rectifying potassium current (IK1) were studied in the single myocytes isolated from adult mouse ventricles by the whole-cell patch-damp technique for the first time. Most of the propertie...The properties of the inward-rectifying potassium current (IK1) were studied in the single myocytes isolated from adult mouse ventricles by the whole-cell patch-damp technique for the first time. Most of the properties of IK1 including channel conductances, activation, inactivation, rectification and external K+ sensitivity in mouse ventricular myocyte were similar to those in other species, but the current-voltage (1-V) curve of mouse ventricular myocyte showed no negative slope, i.e the slope in the range of membrane potential 50 mV positive to the reversal potential (VRev) was virtually flat and remained at a low current level ((59±39) pA). Under the superfusion of Tyrode's solution with 3mmol/L K+ and 3mmol/L Cs+, IK1 in the above region nearly decreased to zero, and then the early after-depolarization (EAD) occurred. The results suggest that this distinctive characteristic of IK1 in mouse ventricular myocyte may relate to the high susceptibility to EA0 in mouse myocardium. The inhibition of IK1 seems to be a prerequisite for the occurrence of EAD in this experiment.展开更多
文摘The properties of the inward-rectifying potassium current (IK1) were studied in the single myocytes isolated from adult mouse ventricles by the whole-cell patch-damp technique for the first time. Most of the properties of IK1 including channel conductances, activation, inactivation, rectification and external K+ sensitivity in mouse ventricular myocyte were similar to those in other species, but the current-voltage (1-V) curve of mouse ventricular myocyte showed no negative slope, i.e the slope in the range of membrane potential 50 mV positive to the reversal potential (VRev) was virtually flat and remained at a low current level ((59±39) pA). Under the superfusion of Tyrode's solution with 3mmol/L K+ and 3mmol/L Cs+, IK1 in the above region nearly decreased to zero, and then the early after-depolarization (EAD) occurred. The results suggest that this distinctive characteristic of IK1 in mouse ventricular myocyte may relate to the high susceptibility to EA0 in mouse myocardium. The inhibition of IK1 seems to be a prerequisite for the occurrence of EAD in this experiment.
文摘目的观察过氧化氢(H_(2)O_(2))对兔离体左室复极相关电生理指标及心律失常的影响。方法制备经冠状动脉灌注兔左室楔形组织块标本。实验分为对照组(灌注正常台式液)和实验组(灌注正常台式液+1.0 mmol/L H_(2)O_(2))。两组依次给予基础周长(BCL)为2 000、1 000、500 ms的刺激,持续时间依次为7、1、0.5 min,观察QT间期、T波峰值至终点的时程(Tp-e间期)、Tp-e/QT、ΔQT、ΔTp-e、ΔTp-e/QT、ΔQT%、ΔTp-e%、ΔTp-e/QT%的变化,及是否发生早后除极、晚后除极及室性心律失常。结果对照组和实验组QT间期、Tp-e间期均随刺激周长的增加而延长,且实验组呈现慢频率依赖性(P<0.01)。在2 000 ms BCL刺激下,对照组Tp-e/QT随时间无明显变化,但实验组Tp-e/QT随H_(2)O_(2)作用时间延长呈先增大后减小的变化趋势,其值始终大于对照组(3 min P<0.05,4~9 min P<0.01),而且与对照组相比实验组发生了不同程度的室性心律失常(P<0.001)。结论 H_(2)O_(2)对复极相关电生理指标的影响表现为慢频率依赖性;慢频率条件下,跨壁复极异质性的电生理指标呈先增大后减小的时间依赖性变化,同时也增加复极相关室性心律失常发生风险。
