苄基四氢巴马汀对大鼠心室肌细胞瞬时外向钾电流的影响

利用全细胞膜片钳技术测定大鼠心室肌细胞的I_to, 研究苄基四氢巴马汀（BTHP）对大鼠心室肌瞬时外向钾电流 (I_to) 的影响. 结果显示，5.0 μmol·L^-1 BTHP可以降低I_to， 使I_to幅值从（13.8±2.2）pA·pF^-1降至（5.1±1.4）pA·pF^-1（P＜0.01）. 在1～100 μmol·L^-1范围内BTHP的作用呈浓度依赖性，IC₅₀为3.6 μmol·L^-1，该药不改变I_to 电流-电压曲线的形状，而使电流幅值减少. 5.0 μmol·L^-1 BTHP使稳态激活曲线右移，半激活电压（V_1/2）从（－6.8±0.2）mV移至（－1.5±0.1）mV，但曲线斜率基本不变. BTHP对失活曲线影响不大，5.0 μmol·L^-1 BTHP使通道失活后恢复时间常数从（75±19）ms延长为 （119±21）ms（P＜0.01）. 结果说明，BTHP浓度依赖地阻滞大鼠心室肌细胞的I_to.

Effect of benzyltetrahydropalmatine on transient outward potassium current in rat ventricular myocytes

To investigate the effects of benzyltetrahydropalmatine (BTHP) on the transient outward potassium currents（I_to）, I_to were recorded in rat single ventricular myocytes by using whole cell patch clamp technique. The results showed that 5.0 μmol·L^-1 BTHP significantly reduced I_to from （13.8±2.2）pA·pF^-1 to （5.1±1.4）pA·pF^-1（P＜0.01，n=6）. BTHP 1－100 μmol·L^-1 reduced I_to in a concentration- dependent manner, IC₅₀ was 3.6 μmol·L^-1. Furthermore, 5.0 μmol·L^-1 BTHP shifted the half-point of activation potential （V_1/2）from （－6.8±0.2 ）mV to （－1.5±0.1）mV. BTHP increased the recovery time constant (τ) from(75±19)ms to (119±21)ms （P＜0.01，n=6）. The results indicate that BTHP inhibits I_to in a concentration- dependent manner.