弱激光对神经细胞膜延迟整流钾通道电流特性的影响

Effects of Low Level Laser Irradiation on Delayed Rectifier Potassium Current in Neuron Membrane

利用波长650 nm,功率5 mW的半导体激光器照射急性分离的大鼠海马CA3区锥体神经细胞,应用全细胞膜片钳技术研究其延迟整流钾通道的电流特性。实验发现,弱激光对延迟整流钾电流IK有抑制作用,且抑制呈时间依赖性,5min激光抑制作用达到稳定,抑制百分比为34.54%±3.22%(统计样本数n=15);弱激光对IK的抑制作用还具有电压依赖性和可逆性,对照组、照射组和恢复组最大激活电流密度分别为429.78±41.40 pA/pF,283.26±39.62 pA/pF(n=10,t检验中P<0.01)和397.22±36.81 pA/pF(n=10,P>0.05);激光作用可显著地影响IK的激活过程,对照组和照射组半数激活电压分别为5.74±1.56 mV和20.98±8.85 mV(n=10,P<0.01),斜率因子分别为16.51±6.67 mV和17.44±5.19 mV(n=10,P>0.05)。结果表明,弱激光作用海马神经细胞可以改变其延迟整流钾通道特性,从而影响动作电位复极化过程,调节神经细胞的生理功能,有利于受损神经元的恢复和再生。

Acutely isolated rat hippocampal CA3 pyramidal neurons were irradiated with a semiconductor laser of 650 nm wavelengh and 5 mW power, and properties of delayed rectifier potassium （K^＋ ） channel were studied using the whole-cell patch clamp technique. The experiment indicated that low level laser reversibly reduced the amplitudes of IK in a time-dependent and voltage-dependent manner. The percentage of inhibition was up to 34.54%±3.22% （n = 15） in irradiating 5 min. The maximum activated current densities of control group, irradiation group and restoration group respectively were 429.78±41.40 pA/pF, 283.26±39.62 pA/pF （n= 10, P〈0.01） and 397.22±36.81 pA/pF （n = 10, P 〉 0.05）. Laser irradiation significantly affected the activation process of IK. The halfactivation voltage and the slope factor of the activation curves were also changed by the laser＇s exposure. The half- activation voltages of control group and irradiation group were 5.74±1.56 mV and 20.98±8.85 mV （n = 10, P 〈 0.01） respectively, and the slope factors were 16. 51±6. 67 mV and 17. 44±5. 19 mV （n = 10, P 〉 0.05） respectively. The results show that low level laser can change the properties of delayed rectifier K＋ channel. Therefore, repolarization process of action potential is affected. Further, physiological functions of neurons are adjusted, which might contribute to the restoration and regeneration of injured neurons.