弱激光对神经元钠电流及动作电位特性的影响

Effects of Low-level Laser Irradiation on Sodium Currents and Action Potential of Neurons

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区锥体神经元,应用全细胞膜片钳技术研究其电压门控Na+通道及神经元动作电位发放特性.实验发现:弱激光照射使神经元钠通道激活电位向超极化方向移动,钠电流峰值增大,且这种增大作用具有电压依赖性和可逆性.激光作用可显著影响钠通道激活和失活过程,使激活和失活曲线发生移动.弱激光照射降低了神经元静息电位及动作电位阈值,使动作电位幅度增大,时程增加,发放频率减慢.结果表明弱激光作用可诱导神经元钠通道特性改变,影响动作电位特征,进而引起神经元生理功能发生变化.

Freshly isolated rat hippocampal CA3 pyramidal neurons were irradiated with a semiconductor laser of wavelengh 650 nm and power 5 mW. And the characteristics of voltage-gated Na^＋ channel and action potential firing of neurons were investigated using the whole-cell patch clamp technique. The experiment revealed that the activated potential of Na^＋ channel shifted towards hyperpolarization direction in irradiating 5 min. And the peak amplitudes of INa increased in a voltage-dependent and reversible manner. The activation and inactivation process of INa were markedly affected by laser action. The resting potential and threshold potential of neurons declined, action potential amplitude increased, action potential duration widened,frequency of firings slowed under low-level laser irradiating. The results suggest that low-level laser irradiation could induce the change of voltage-gated Na^＋ channel configuration and influence the characteristics of action potential. Therefore, physiological function of neurons was altered as a result of low-level laser irradiation.