Effects of intracellular calcium on GABAA receptors in mouse cortical neurons
Effects of intracellular calcium on GABAA receptors in mouse cortical neurons
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DOI：
10.1007/s004240050527
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发表时间：
1998-02-01
影响因子：
4.5
通讯作者：
Satin, LS
中科院分区：
文献类型：
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作者：
Aguayo, LG;Espinoza, F;Satin, LS
利用膜片钳技术，我们研究了细胞内Ca2+对小鼠皮质神经元中A型γ -氨基丁酸受体（GABA(A)）门控Cl-电流的影响。当快速Ca2+螯合剂1,3-双（2-氨基苯氧基）乙烷-N，N，N‘，N’-四乙酸（BAPTA）存在于移液液中时，GABA激活的Cl-电流振幅随时间下降至对照的49 +/- 7%。相反，用乙二（氧硝基）四乙酸酯（EGTA）等摩尔取代BAPTA会使GABA电流增加60 +/- 10%。细胞内Ca2+浓度的增加引起GABA电流的短暂增强。Ca2+的这种作用是浓度依赖性的（10 nM至34 μ M）。Ca2+通过增强对GABA的最大反应而不是通过改变受体对GABA的亲和力来增加电流的振幅（EC50 = 5 +/- 0.4 μ M vs. 7 +/- 0.3 μ M）。钙调素（CaM）和CaM激酶II抑制剂（200 μ M）都阻断了Ca2+的增强作用，表明这是由CaM激酶II的激活介导的。我们发现，皮质神经元细胞内Ca2+对GABA(A)受体的调节具有重要的生理意义，因为增加细胞内Ca2+对GABA反应的增强作用可以通过100 μ M n -甲基- d -天冬氨酸（NMDA）激活兴奋性受体来模拟。这些发现表明，谷氨酸对GABA(A)受体活性的调节可能是通过细胞内Ca2+的变化来实现的。
Using the patch-clamp technique, we studied the effect of intracellular Ca2+ on Cl- current gated by type A gamma-aminobutyric acid receptors (GABA(A)) in mouse cortical neurons, When the rapid Ca2+ chelator 1,3-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) was in the pipette solution, the GABA-activated Cl- current amplitude decreased over time to 49 +/- 7% of control. In contrast, equimolar replacement of BAPTA with ethylenebis(oxonitrilo)tetraacetate (EGTA) caused a 60 +/- 10% increase in GABA current. An increased intracellular Ca2+ concentration caused a transient augmentation of the GABA current. This effect of Ca2+ was concentration dependent (10 nM to 34 mu M) Ca2+ increased the amplitude of the current by enhancing the maximal response to GABA rather than by changing the affinity of the receptor to GABA (EC50 = 5 +/- 0.4 mu M vs. 7 +/- 0.3 mu M). Both calmodulin (CaM) and a CaM kinase II inhibitor (200 mu M) blocked the potentiating effect of Ca2+ suggesting that it was mediated by activation of CaM kinase II. We found that regulation of GABA(A) receptors by intracellular Ca2+ in cortical neurons has important physiological implications since the potentiating effect of increasing the intracellular Ca2+ on responses to GABA was mimicked by activating excitatory receptors with 100 mu M N-methyl-D-aspartate (NMDA). These findings suggest that modulation of GABA(A) receptor activity by glutamate may be brought about via changes in intracellular Ca2+.