硫酸镁对大鼠海马CA_1区神经元钠电流的抑制作用

Inhibition of sodium currents in acutely isolated hippocampal CA_1 neurons of rats by magnesium sulfate

利用全细胞膜片钳技术研究了硫酸镁 (MgSO4 )对大鼠海马CA1区神经元钠电流的影响。结果表明 ,MgSO4 可浓度依赖和电压依赖地抑制钠电流 ,半数抑制浓度为 4 0 5mmol/L。这一抑制作用与刺激频率无关。结果还表明 ,4mmol/LMgSO4 不影响钠电流的失活过程 ,却使半数激活电压由 - 5 5 8± 6 8mV变为 - 3 4 2± 6 2mV (n =8,P <0 0 1) ,而激活曲线的斜率因子不变。结果提示 ,MgSO4

The effects of magnesium sulfate (MgSO 4) on sodium currents (Na + currents) were studied in freshly dissociated hippocampal CA 1 neurons of rat using the whole-cell patch-clamp technique. The results indicated that MgSO 4 caused a concentration-dependent and voltage-dependent decrease in Na + currents. The half-inhibitory concentration (IC 50) was 4.05 mmol/L. This action was frequency-independent. The results also showed that 4 mmol/L MgSO 4 shifted the steady state activation curve of Na + currents towards positive potential (control V h=-55.8±6.8 mV, MgSO 4 V h=-34.2±6.2 mV, n=8, P<0.01) without changing the slope factor. However, the steady state inactivation curve was not affected. These results suggest that blockade of Na + currents by MgSO 4 might be an interpretation for its neuroprotection against damages induced by ischemia and oxygen deprivation.