不同强度工频磁场对皮层神经元瞬时外向钾离子通道的影响

人们对电磁辐射越来越关注,但是工频磁场产生的生物效应并不确定.选用1、5、10 mT的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瞬时外向钾通道电流,研究工频磁场对离子通道的影响.结果显示:工频磁场抑制通道的电流密度,并且1 mT、5 mT及10 mT工频磁场的抑制率分别为(63.0±2.2)%、(55.0±1.7)%和(38.0±1.8)%.工频磁场影响离子通道的激活和失活特性,半数激活电压和半数失活电压变小.不同强度工频磁场对离子通道产生的影响程度不同,其中1 mT工频磁场对通道电流的抑制率最大,5 mT工频磁场对通道的半数激活电压和半数失活电压影响最大,10 mT工频磁场增大了通道的失活斜率因子.研究结果表明,工频磁场影响了细胞膜上离子通道蛋白质构象的变化,进一步影响了离子通道的正常功能.

Effects of 50 Hz Magnetic Fields With Different Intensities Exposure on Transient Outward Potassium Channel of Cortical Neurons

Despite growing concern about electromagnetic radiation, the biological effects of the frequency magnetic fields remain obscure. The cortical neurons isolated from the mice were exposed to a 50 Hz electromagnetic field (EMF 1 mT, 5 mT, 10 mT) for 15 min. Using the whole-cell patch clamp technique, the currents of the transient outward potassium channel were recorded off-line, and then the effects of EMF on the channels were investigated. Compared to the control group, a significant inhibition on the I_A was reported, and the rate of inhibition were (63.0 ± 2.2)% (1 mT), (55.0 ± 1.7)% (5 mT), (38.0 ± 1.8)% (10 mT), respectively. Moreover, the characteristics of activation and inactivation were both influenced by EMF, because there were a decreasing both on the half activation voltage and the half inactivation voltage. Additionally, different effects on the channels had been found for the different intensities. In the research, the maximum inhibition rate of current was induced by 1 mT, and the changing of the half activation voltage and the half inactivation voltage were the biggest after exposure to 5 mT, and 10 mT EMF increased the slope factor of inactivation. The results indicated that EMF affected the conformational changes of ion channel protein on cell membrane, and further influenced the normal function of ion channels.