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目的 采用全细胞膜片钳技术 ,研究了镁离子 (Mg2 +)对培养的大鼠海马神经元γ 氨基丁酸A型 (GABAA)受体所介导电流的作用。方法 采用EPC 9型膜片钳放大器对培养的大鼠海马神经元进行全细胞记录 ,记录浓度为 3、30、30 0 μmol/L的γ 氨基丁酸A型 (GABA)所引发的电流及合用 80 μmol/L的Mg2 +时对其的影响。结果 在钳制电压为 -4 0mV时 ,GABA可通过GABAA受体介导产生内向电流 ,且随GABA的浓度增高 ,电流峰值增高 ,EC5 0和Hillcoefficient分别是 2 0 μmol/L和 0 .7( n =7) ;在Mg2 +存在的情况下 ,GABA的浓度 效应曲线向左、向上移动 ,EC5 0和Hillcoefficient分别是 10 μmol/L和 0 .7。 结论 推测Mg2 +能通过正性变构调节机制影响GABAA受体的功能。
OBJECTIVE: To study the effect of magnesium ion (Mg2 +) on the currents mediated by γ-aminobutyric acid type A (GABAA) receptors in cultured rat hippocampal neurons using whole-cell patch clamp technique. Methods Whole-cell recordings of neurons in cultured rat hippocampus were performed by EPC 9 patch clamp amplifier. The currents induced by γ-aminobutyric acid A (GABA) at concentrations of 3, 30 and 30 μmol / L were recorded. Effect of 80 μmol / L Mg2 + on it. Results When the clamping voltage was -4 0 mV, GABA could induce inward current through the GABAA receptor. With the increase of GABA concentration, the current peak increased. The EC50 and Hillcoefficient were 20 μmol / L and 0. 7 (n = 7). In the presence of Mg2 +, the concentration-response curves of GABA moved left and upwards with EC50 and Hillcoefficient of 10 μmol / L and 0.7, respectively. Conclusion It is speculated that Mg2 + can affect the function of GABAA receptor through the positive allosteric regulation mechanism.