体外暴露900MHz射频磁场对小鼠神经元电压门控Na^+通道的影响

Effect of in vitro Exposure to 900 MHz Radio Frequency Magnetic Field on Mice Neuron Voltage-Gated Sodium Channel

[目的]研究手机900 MHz射频磁场对小鼠脑皮质神经元Na+通道的影响。[方法]选取7～10 d鼠龄的昆明小鼠(乳鼠),取其活脑组织切片,经酶解消化、孵育后,采用酶解和机械相结合的分离方法制备小鼠脑皮质神经元。对照组及3个暴露组均记录10个细胞。采用900 MHz、发射功率为398.1 mW的射频磁场作用3个磁场暴露组5、10和15 min后,应用全细胞膜片钳技术观测各组细胞膜电压门控Na+通道,与对照组比较,探究其对神经元动作电位的影响。[结果]900 MHz磁场暴露使神经元Na+通道激活电位向超极化方向移动,Na+电流峰值增大,使得Na+通道激活和失活曲线向超极化方向移动:对照组与磁场暴露组半数激活电压分别为(-34.983±0.34)mV和(-43.137±0.56)mV(P<0.05),斜率因子k分别为(2.334±0.15)mV和(2.339±0.36)mV(P>0.05);半数失活电压分别为(-55.809±0.189)mV和(-63.64±0.627)mV(P<0.05),斜率因子k分别为(4.40±0.147)mV和(5.737±0.54)mV(P>0.05)。[结论]900 MHz磁场暴露小鼠皮层神经元可改变Na+通道的跨膜离子电流-电压(I-V)特性、激活和失活特性,从而使得动作电位的开启提前和加速快速上升阶段,使得神经元细胞更加兴奋并且促进动作电位的传导,影响神经元的生理功能。

[ Objective ] To invesitgate the effect of 900 MHz radio frequency magnetic field emitted by mobile phone on sodium channels of mouse cortical neurons. [ Methods ] Brain tissues of Kunming mice at age of 7-10 days were sliced, digested, and incubated for preparation of cortical neurons using combined enzymatic and mechanical separation. For each group, 10 cells were recorded. Three exposure groups were treated with 900MHz and 398.1 mW radio frequency magnetic field for 5, 10, or 15 rain, respectively. The characteristics of transient s^um current （I Na） were recorded using whole-cell patch-clamp technique to explore the impacts on the action potentials of neurons. [ Results ] The half-activation voltage of sodium channel was hyperpolarized and the current peak was increased under 900 MHz, and the magnetic field shifted the steady-state inactivation and the activation curve in a hyperpolarized direction. The half-activation voltage changed from （-34.983 ± 0.34）mV to （-43.137 ± 0.56）mV after the exposure （P〈0.05）, and the slope factor changed from （2.334 ± 0.15）mV to （2.339 ± 0,36）mV （P〉0.05）. The half-inactivation voltage changed from （-55.809 ± 0.189）mV to （-63.64 ± 0.627）mV （P〈0.05）, and the slope factor changed from （4.40 ± 0.147）mV to （5,737 ± 0.54）mV （P〉0.05）. [ Conclusion ] Exposure to 900MHz magnetic field may change the transmembrane ionic current- voltage （I-V） characteristics and the activation ＆ inactivation characteristics of mice cortical neurons＇ Na channel. It also antedates action potentials and accelerates rising phase, improving excitability of neuron cells and conduction of action potential, and finally affects the physiological functions of the neurons,