甘松挥发油对大鼠心室肌细胞瞬时外向钾电流的影响

Effects of the Volatile Oil of Nardostachys chinensis on Transient Outward Potassium Current in Isolated Ventricular Myocytes in Rats

目的研究甘松挥发油对大鼠心室肌细胞膜瞬时外向钾电流(Transient outward potassium current,Ito)的影响,探讨甘松挥发油抗心律失常作用的离子机制。方法用急性酶解分离法获得单个大鼠心室肌细胞,采用标准的全细胞膜片钳技术记录大鼠心室肌细胞膜瞬时外向钾电流(Ito)。结果甘松挥发油可呈浓度依赖性和电压依赖性抑制Ito。在+70mV时,3μg/g,6μg/g,10μg/g和20μg/g甘松挥发油分别抑制Ito峰值电流的抑制率为(27.01±6.93)%(n=5),(51.13±9.82)%(n=5),(80.86±4.63)%(n=5)和(94.81±4.30)%(n=5)。甘松挥发油对Ito的电流密度-电压关系曲线(current density-voltage curve,I-V曲线)的影响:在+70 mV时,6μg/g甘松挥发油使Ito峰电流从(23.081±0.74)pA/pF减少到(11.232±1.47)pA/pF(n=5,P<0.05),给药后电流密度减少约50%,给药前后电流密度变化有统计学意义。甘松挥发油对Ito激活和失活曲线的影响:在甘松挥发油6μg/g灌流法给药后,激活曲线显示给药前后半数激活电压(V1/2)为:(36.063±1.792)mV vs(34.788±3.029)mV(P>0.05,n=5);斜率因子(S)为:(22.972±1.491)mV vs(30.791±2.899)mV(P<0.05,n=5)。给药前后半数激活电压变化无显著差异。失活曲线显示甘松挥发油使失活曲线明显左移,差异有显著统计学意义:给药前后半数失活电压(V1/2)为(-33.738±0.476)mV vs(-40.536±0.696)mV(n=5,P<0.01);斜率因子(S)为:(5.001±0.396)mV vs(8.420±0.620)mV(n=5,P<0.01)。结论甘松挥发油可呈浓度和电压依赖性抑制大鼠心室肌细胞Ito,使I-V曲线下移,但对激活曲线无明显影响,同时,使失活曲线明显左移,使心室肌细胞复极化减慢,这可能是其抗心律失常作用的重要机制之一。

Objective To observe the effects of the volatile oil of Nardostachys chinensis （VONC） on transient outward potassium current in isolated ventricular myocytes in rats. Methods Single ventricular myocyte of rats were obtained by enzymatic dissociation. The whole - cell patch clamp recording technique was used to record the change of Ito current by the effect of the volatile oil of Nardostachys chinensis. Results 1. The volatile oil of Nardostachys chinensis could reduce the Ito current with dose - dependent block manner. At concentrations of 3, 6, 10 and 20 μg/g, the peak Ito current was respectively reduced （27.01± 6.93 ）% （n=5, P〈0.05）, （51.13±9.82）% （n=5, P〈0.05）, （80.86±4.63）% （n=5, P〈0.05） and （94.81±4.30）%（n = 5, P 〈 0.05 ）. 2. The volatile oil of Nardostachys chinensis also could reduce Ito corrent in voltage - dependent block manner. The current density of ho was impacted by the concentration at 6μg/g of the volatile oil of Nardostachys chinensis. The peak current density of Ito was reduced to 11.23 ± 1.47pA/pF from 23.08 ＋ 0.74pA/pF （ n = 5, P 〈 0. 01 ） at membrane potential of ＋ 70 mV after treatment with the volatile oil of Nardostachys chinensis at 6 μg/g. It was reduced about 50%. 3. The activity curve had no significant change after treatment with the volatile oil ofNardostachys chinensis （6μg/g）. Their V1/2 were （36. 063 ± 1. 792）mV vs （34.788±3.029） mV（n=5, P〉 0.05） and slope were （22.972±1.491） mV vs （30.791 ±2.899） mV（n=5, P 〈 0.05 ）. The inactivation curve was shifted towards the negative direction after treatment with the volatile oil of Nardostachys chinensis（6 μg/g）. Their Vie2 were （ -33. 738 ±0. 476） mV vs （ -40. 536 ±0. 696） mV （ n =5, P 〈0.01 ） and Slope were（5. 001 ± 0. 396） mV vs （8. 420 ± 0. 620） mV （ n = 5, P 〈 0. 01 ）. Conclusion The volatile oil of Nardostachys chinensis exercutes the blocked function to Ito in dose dependent and voltage dependent manners, and its dosage alters the Ⅰ - Ⅴcurve, but does not alter the active curve.