丹皮酚对家兔心室肌细胞瞬时外向钾电流的抑制作用

Inhibitory Effect of Paeonol on Transient Outward Potassium Current of Rabbit Ventricular Myocytes

目的 探讨丹皮酚（Paeonol，Pae）对家兔心室肌细胞瞬时外向钾电流（transient outward potassium current，Ito）及其动力学的影响。方法 用酶解法分离单个兔心室肌细胞。全细胞膜片钳技术记录Pae对兔心室肌细胞Ito的影响前后变化。结果 Pae 100μg／ml作用心肌细胞5min，可使Ito明显减小。指令电位为＋50mV时，可使Ito从（41．45±5．89）pA／pF减少到（8．97±2．78）pA／pF，两者之间有显著性差异（n=6，P〈0．01）。冲洗15min后，Ito部分恢复至（39．74±0．82）pA／pF（n=6，P〈0．0I，与给药后比较），接近给药前的峰值，表明该药对Ito的抑制作用是可逆的。在50～400μg／ml范围内，Pae对Ito的抑制作用表现为浓度依赖性，IC50的平均值为101．55μg／ml。Pae 100μg／ml使各膜电位水平下Ito减小，Ⅰ—Ⅴ曲线下移。Pae不改变Ito稳态激活动力学曲线。但使失活动力学曲线显著左移，即向超极化方向移动，50％Ito失活曲线点分别为（-45．3±3．5）mV和（-81．19±2．9）mV（n=8，P〈0．01）．与对照组相比，差异有显著性。同时可使Ito失活后恢复时间延长，用药前后50％Ito恢复时间分别为（20．1±2．5）ms和（45．1±2．2）ms（n=8，P〈0．01），与对照组相比，有显著性差异。结论 Pae对家兔心室肌细胞Ito具有显著的抑制作用．这可能是Pae发挥抗心律失常作用的另一电生理基础。

Objective To investigate the effect of Paeonol（Pae） on transient outward potassium current （Ito） and its kinetic behaviors of isolated ventricular myocytes of rabbit. Methods Single ventricular myocytes were enzymatically dissociated from adult rabbits. Whole-cell patch clamp technique was used to record voltage-dependent ho. Results （1） Pae 100μg/rnl significantly inhibited ho in a vohage-dependent way. With command potential at ＋50mv, the peak current of Ito was significantly decreased from（41.45 ±5.89） pA./ pF to （8.97± 2.78）pA/pF（ n = 6, P 〈 0.01）. After washout in 15min, Ito was recovered to （39.74 ± 0.82） pA/pF（n =6, with control P 〉 0.01）. （2） It significantly reduced Ito in a clear concentration-dependent manner at the range of 50 ～400μg/ml with an IC50 value of 101.55μg/ml. （3） Pae 100μg/ml markedly shifted Ⅰ-Ⅴ curve downward but didn＇t chang the shape of Ⅰ-Ⅴ curve . （4） Activation curve of Ito wasn＇ t significantly changed before and after administration of Pae 100μg/ml. However, Pae 100μg/ml obviously shifted the inactivation curve leftward, with 50% voltages of inactivation curves of Ito were（ -45.3 ±3.5） mV and（ - 81.1 ±2.9） mV（ n = 8, P 〈 0.01）, respectively. （5） With perfusion Pae 100μg,/ml, the 50% recovering time of inactivation curve of I,, were（20.1 ± 2.5） ms and（45.1 ± 2.2） ms（ n = 8, P 〈 0.01）, respectively. Conclusion Pae blocked Ito in rabbit ventrieular myocytes. This may be one of ionic channel mechanisms of Pae in the treatment of antiarrhythmia.