不同强度工频磁场对神经元延迟整流钾通道特性的影响

Effects of 50 Hz Magnetic Fields With Different Intensities Exposure on Delayed Rectifier Potassium Channel of Neurons

工频磁场是人类生活中接触最多的一类磁场,其引起的生物效应与人类健康的关系备受关注.本文选用1 mT、5 mT及10 mT工频磁场照射急性分离的小鼠皮层神经元(15 min),应用全细胞膜片钳技术离线记录通道电流,研究了工频磁场对神经元延迟整流钾通道特性的影响.结果显示,1 mT、5 mT及10 mT 3个强度的工频磁场对Ik均有抑制作用,但随着去极化电压的增加,发现1 mT和5 mT工频磁场的抑制率几乎不变,抑制率分别为(30±4.2)%和(20±2.2)%,而10 mT工频磁场的抑制率增加,最大抑制率为43.4%.另外,1 mT和5 mT工频磁场影响了延迟整流钾通道的激活特性,通道的半数激活电压变大,斜率因子不变.而10 mT工频磁场对通道的激活特性没有影响,半数激活电压和斜率因子均不改变.研究表明,工频磁场可能影响了细胞膜上离子通道蛋白质的结构和功能,并且不同强度工频磁场对通道的影响不同,存在强度窗口效应.

There is a growing concern about the relationship between the human health and the biological effects caused by the magnetic fields exposure.The cortical neurons isolated from the mice were exposed to 50 Hz magnetic fields（EMF 1 mT,5 mT,10 mT） for 15 min,and then the currents of the delayed rectifier potassium channel were recorded off-line using the whole-cell patch clamp technique to investigate the effects of EMF on channels for the first time.Compared to the control group,there was a significant inhibition on the Ik after exposure to EMF,and with the increase of the voltage depolarization,the inhibition rates of 1 mT and 5 mT almost unchanged and the inhibition rates were（30.0 ± 4.2）% and（20.0 ± 2.2）%,respectively.While the inhibition rate of 10 mT became larger and the maximum inhibition rate was 43.4%.Additionally,1 mT and 5 mT magnetic fields both affected the activation characteristics of delayed rectifier potassium channel,the half activation voltage became larger and the slope factor unchanged,while 10 mT magnetic fields did not changed anything.This paper indicated that the structure and function of the channel protein on cell membrane may be altered by 50 Hz EMF,and there were different effects on the channel for different strength of magnetic fields,the window effects of strength of magnetic fields were improved in this study.