灯盏花素对大鼠心室肌细胞瞬间外向和内向整流钾电流的影响

Effect of breviscapin on I_(to) and I_(K1) channel current in isolated ventricular myocytes of rats

目的:研究灯盏花素对大鼠心室肌细胞膜瞬间外向钾电流(Ito)和内向整流钾电流(IK1)的影响,在离子通道水平探讨灯盏花素的抗心律失常作用机制。方法:用急性酶解法获得单个大鼠心室肌细胞,标准的全细胞膜片钳技术记录Ito和IK1。结果:(1)灯盏花素呈浓度依赖性抑制Ito,在+50mV时,0.02、0.05、0.08、0.10(g.L-1)灯盏花素分别阻断Ito峰电流(10.07±0.30)%、(27.47±1.25)%、(42.72%±1.30)%和(56.09±2.10)%,冲洗后可以完全恢复。在+50mV时,0.10g.L-1灯盏花素使峰电流从(29.61±3.40)pA/pF减少至(13.00±1.80)pA/pF(n=5,P<0.05)。(2)灯盏花素呈电压依赖性抑制Ito,在0^+50mV,各浓度随电压增加抑制作用明显减弱。(3)0.10g.L-1灯盏花素对Ito失活、激活和复活曲线无明显影响。(4)0.10g.L-1灯盏花素对IK1无明显影响。结论:灯盏花素能够抑制心肌细胞Ito,呈浓度依赖性和电压依赖性,对IK1无明显影响,这可能是其抗心律失常作用的重要机制之一。

AIM： The effects of breviscapin on transient outward potassium current （Ito） and inward rectifier potassium current （ IK1 ） channel in isolated ventricular myocytes of rats were determined. The mechanism of breviscapin at the ionic channel level was explored. METHODS： Single ventricular myocyte of rats was isolated by enzymatic dissociation. The whole - cell patch - clamp recording technique was used to record the change of Ito and IK1 channel current influenced by breviscapin. RESULTS ： Breviscapin decreased the Ito channel current in a dose - dependent and voltage - dependent manner in ventricular myocytes of rats. （ 1 ） The current - voltage curve was significantly decreased. Breviscapin at concentrations of 0. 02, 0. 05, 0. 08, 0. 10 g · L^-1 respectively decreased Ito current density （10. 07 ± 0. 50）%, （27.47 ± 2. 36） %, （42.72% ± 2. 50） % and （ 56. 09 ± 5. 60） %. Ito was inhibited in a voltage - dependent manner, showing a significant attenuating effect at test potentials from 0 to ＋ 50 inV. （2） The Ito activation curve, the activation curve and the recovery curve were not altered. （3） Breviscapin did not affect IK1. CONCLUSION ： Breviscapin concentration - dependently decreases Ito channel current in ventricular myocytes of rat.