人胚肾细胞心脏钠通道电流的频率和电压依赖性阻滞及其失活

Na^+ current block with holding potential and voltage-dependant and current inactivation of Na_v1.5 in human embryonic kidney cells.

目的用人胚肾(HEK)细胞研究纯心脏钠通道电流(Nav1.5)频率、电压依赖性及快、慢钠通道失活以及利多卡因对其影响。方法用膜片钳技术,观察两次刺激脉冲间隔钠电流对频率,电压依赖性阻滞程度。通过两种不同刺激程序产生快、慢钠电流并记录其失活过程。并观察0.1 mmol/L利多卡因对钠电流的频率依赖性阻滞。结果电压钳制在-140 mV时钠电流抑制随频率刺激脉冲间隔时间缩短而阻滞加重。完全恢复正常平均值为33.2±5.77ms(n=9),当电压钳制在-90,-100 mV时,钠电流完全恢复正常延迟至1 015 ms。快钠电流失活随钳制电压降低而加重,并呈现负相关(r=-0.97,P<0.01),慢钠电流失活随钳制电压变化不甚明显。0.1 mmol/L利多卡因在-100 mV电压钳制下,导致20%Na+电流抑制,静息状态下产生轻微阻滞;且抑制随刺激频率增加而增加。结论HEK细胞Nav1.5通道电流频率依赖性阻滞恢复与刺激频率、钳制电压高低有关;快钠电流失活随钳制电压降低而加重并呈负相关;利多卡因对HEK细胞Nav1.5通道有加重频率依赖性阻滞作用且随刺激频率增加而增加。

Objective To investigate the course of recovery from holding potential, vohage-dependant block and fast, slow sodium inactivation of Na, 1.5 in human embryonic kidney （HEK） cells, and to verify the effects of Lidocaine on them. Meth- ods The two pulses of recovery and test pulse were generated with interval duration varying from 16 ms to 1 020 ms and holding potential was from - 80 to - 140 mV. Fast and slow sodium inactivation were induced by special stimulating program. The effects of Lidocaine on recovery from voltage-dependant block of Nav 1.5 in HEK were also tested. Results It showed that the time courses of recovery from frequency-dependent block was 33.2 ± 5.77 ms （ n = 9） at - 140 mV for holding potential （Hp）. However, it delayed to 1 015 ms when Hp = -90 mV or -100 inV. There was negative relationship between fast sodium inacti- vation and Hp changing （r = -0.97 ,P 〈0.01 ）. However, there was no clear relationship between slow sodium inactivation and Hp changing. In the presence of 0. 1 mmolfL Lidocaine, Hp = - 100 mV, mad 30 s of interval, 20% of amplitude of sodium cur- rent was decreased in the resting state. Lidocaine 0. 1 mmol/L showed frequency-dependant block of Nail. 5 in HEK by increas- ing frequency from 1Hz to 20 Hz. Conclusion There is relationship between course of recovery from voltage-dependant block of Na,1.5 in HEK cells and the frequency of stimulation and Hp changing; There is negative relationship between fast sodium in- activation and Hp changing; Lidocaine showed more frequency-dependant block of Nav 1.5 in HEK cells by increasing frequency from 1Hz to 20Hz. [ Chinese Journal of Cardiac Pacing and Electrophysiology,2009,23（ 1 ）：43 -46]