0.5 mT工频磁场对小鼠海马CA3区锥体神经元延迟整流钾离子通道和动作电位的影响

Effects of 0.5mT power frequency electromagnetic fields on delayed rectifier potassium channels in hippocampns CA3 pyramidal neurons

目的 研究与日常生活密切相关的0.5 mT工频磁场对小鼠海马CA3区锥体神经元的影响.方法 采用急性分离的方法制备小鼠海马CA3区锥体神经元,用0.5 mT、50 Hz磁场对小鼠海马CA3区锥体神经元刺激30 min后,运用全细胞膜片钳技术研究其延迟整流钾通道电流,Ik和动作电位特性.结果 0.5 mT工频磁场照射小鼠海马CA3区锥体神经元30 min后,其电流密度减小,对照组和曝磁组最大电流密度分别为（171.05＋1.32）pA/pF、（139.65±2.37）pA/pF（n=12,P〈0.05）;对照组和曝磁组半数激活电压分别为（7.44±0.64）mV、（34.09＋6.48）mV（n=12,P〈0.05）;斜率因子分别为11.36±0.57、19.97±3.45（n=12,P〈0.05）;动作电位复极化时程APD90由（14.63±0.34）ms延长为（21.74±1.47）ms（n=12,P〈0.05）.结论 0.5 mT工频磁场可使小鼠海马CA3区锥体神经元延迟整流钾通道电流Ik减小,通道开放延迟,通道激活速度减慢,动作电位复极化时间延长.

Objective To study the effects of 0.5mT power frequency electromagnetic fields on hippocampus CA3 pyramidal neurons. Methods Hippocampus CA3 pyramidal neurons of rats were prepared by acute isolation and then exposed to an electromagnetic fields, with frequency of 50 Hz and the intensity of 0.5 mT,for 30 minutes. The delayed rectifier potassium channel currents were recorded by whole-cell patch-clamp technique. Results The results showed that after 30 minutes exposure to the electromagnetic fields, the delayedrectifier potassium channel current density of the rats＇ hippocampus CA3 area pyramidal neurons decreased, with the maximum value of control group was（171.05±1.32） pA/pF, and that of the exposure group was（139.65±2.37）pA/pE（n=12, P〈0.05）. The half-activation potential of control group and that of exposure group were （7.44±0.64）mV and （34.09±6.48） mV（n=12, P〈0.05）, respectively and the slope factor were 11.36±0.57 and 19.97 ±3.45（n=12, P〈0.05）, respectively. APD90 extended from （14.63±0.34） ms to （21.74±1.47） ms （n=12, P〈0.05）. Conclusion It can be speculated that the electromagnetic fields can reduce the currents of delayed rectifier potassium,change the process of activation and increase the half activation potential. After exposure, the activation speed decreased, while the APD increases.