镁离子对大鼠海马神经元γ-氨基丁酸A型受体介导电流的影响

Effect of magnesiumion on GABAA-receptor mediated current in primary cultured rats' hippocampal neuron

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 effects of Mg^(2+) on GABAA-receptor mediated current in primary cultured rats' hippocampal neurons.Methods Whole-cell recording of patch clamp technique wa s used to record GABAA-receptor mediated current in primary cultured rats' hipp ocampal neurons.Results GABA (3,30,300μmol/L) indu ced inward currents in a concentration-dependent mannerby activating GABAA-rec eptor at a holding potential of -40mV.EC50 was 20μmol/L and Hill coefficie nt was 0.7 ((n=7);)GABAA-receptor mediated responses wereenhanced when 8 0 μmol/LMg^(2+) was used simultaneously,the concentration-response curve of GABAA -receptor mediated currents was shifted to the left and the upin parallel manne r,EC50 was 10μmol/L and Hill coefficient 0.7.Conclusion Mg^(2+) might affect the function of GABAA -receptor in some positive allosteric manner.