伊布利特对兔左室中层细胞L型钙电流的影响

目的观察伊布利特对正常心肌细胞L型钙通道电流(ICa-L)的影响。方法用全细胞膜片钳技术记录10-6,10-5mol/L伊布利特细胞外液对兔正常左室中层心肌细胞L型钙通道电流(ICa-L)活性的影响。结果①伊布利特灌流后ICa-LI-V曲线下移,低、高剂量伊布利特灌流后电流密度峰值明显增加(-8.34±2.67,-10.50±3.81pA/pFvs-5.68±1.53pA/pF,P均<0.01),且高剂量较低剂量灌流时增加更明显。②低、高剂量伊布利特灌流后失活曲线右移,且高剂量时右移更明显。高剂量时半数失活电压(V0.5)较低剂量和用药前显著降低,而低剂量与用药前无差异。三种状态的激活曲线无差异。结论伊布利特可能呈浓度依赖性影响心室肌细胞L型钙电流(ICa-L)活性。

Effects of ibutilide on L-type Ca2+ current in isolated left ventricular midmyocardial myocytes of rabbit

Objective To study the effects of ibutilide on L-type Ca2+ current(ICa-L). Methods Front wall midmyocardial of left ventricular were isolated from New Zealand white rabbits . ICa-L in 10-6,10-5mol/L ibutilide was recorded using whole cell patch clamp techniques. Results The activating process of ICa-L of midmyocardial in the perfusion of the different concentration of ibutilide showed obviously voltage-dependency. Ibutilide of 10-6mol/L group and 10-5mol/L group downshifted the I-V curve,and the peak current density at test potential of 0 mV was significantly increased from -5.68±1.53pA/pF(CON group,n=22 cells) to -8.34±2.67pA/pF(n=20 cells) and to -10.5±3.81pA/pF (n=20 cells), P<0.01, respectively. There were also significantly difference between 10-6mol/L and 10-5mol/L group (P<0.05). The half inactivation potential (V0.5) was -34.1±4.2mV (n=18 cells) in CON group, and -32.2±5.6 mV(n=16 cells) in 10-6mol/L group and -18.1±6.9 mV(n=16 cells) in 10-5mol/L group, respectively. There were significantly difference in half inactivation potential between CON group and 10-5mol/L group (P<0.01) and between 10-6mol/L group and 10-5mol/L group (P<0.01).The activation curve was not markedly changed after ibulitide application, but the window current could be enlarged in 10-5mol/L group. Conclusion Ibutilide concentration-dependently effect ICa-L.