Received 2002-04-10 Accepted 2002-08-06

This work was supported by the National Natural Science Foundation of China (No.30070640)

*Corresponding author. Tel/Fax: +86-351-7011895; E-mail: zqmeng@sxu.edu.cn

硫酸镁对大鼠海马CA1区神经元钠电流的抑制作用

桑楠, 孟紫强*

山西大学环境医学与毒理学研究所, 太原 030006

摘要: 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4.05 mmol/L。这一抑制作用与刺激频率无关。结果还表明, 4 mmol/L MgSO4不影响钠电流的失活过程, 却使半数激活电压由-55.8±6.8 mV变为 -34.2±6.2 mV (n=8, P＜0.01), 而激活曲线的斜率因子不变。结果提示, MgSO4抑制大鼠海马CA1区神经元的钠电流可能是其抗缺血缺氧造成的中枢神经系统损伤的机制之一。

关键词: 海马CA1区神经元; 全细胞膜片钳技术; 硫酸镁 (MgSO4); 钠电流

Inhibition of magnesium sulfate on sodium currents in acutely isolated hippocampal CA1 neurons of rat

SANG Nan, MENG Zi-Qiang*

Institute of Environmental Medicine and Toxicology, Shanxi University, Taiyuan 030006

Abstract: The effects of magnesium sulfate (MgSO4) on sodium currents (Na+ currents) were studied in freshly dissociated hippocampal CA1 neurons of rat using the whole-cell patch-clamp technique. The results indicated that MgSO4 caused a concentration-dependent and voltage-dependent reversible decrease of Na+ currents. The half-inhibitory concentration (IC50) of MgSO4 on Na+ currents was 4.05 mmol/L. This action was frequency-independent. The results also showed that 4 mmol/L MgSO4 shifted the steady state activation curve of Na+ currents towards positive potential (control Vh=-55.8±6.8 mV, MgSO4 Vh=-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 MgSO4 might be an interpretation for its neuroprotection against damages induced by ischemia and oxygen deprivation.

Key words: hippocampus; CA1 neuron; patch-clamp technique; magnesium sulfate (MgSO4); Na+ current