Whole-cell voltage-clamp study of the fading of GABA-activated currents in acutely dissociated hippocampal neurons.
Whole-cell voltage-clamp study of the fading of GABA-activated currents in acutely dissociated hippocampal neurons.
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急性分离海马神经元中 GABA 激活电流衰减的全细胞电压钳研究。
DOI：
10.1152/jn.1986.56.1.1
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发表时间：
1986
影响因子：
2.5
通讯作者：
Alger,BE
中科院分区：
文献类型：
--
作者：
Huguenard,JR;Alger,BE
以成年豚鼠海马CA 1区急性分离的神经元为模型系统，研究了哺乳动物中枢神经元对γ-氨基丁酸（GABA）反应的不稳定性。GABA通过压力喷射施加到神经元胞体，并且在全细胞电压钳下记录所产生的电流（IGABA）。在最初的实验中，我们检查了这种制备中细胞的几个基本性质。我们的数据证实，被动和主动膜的性质是类似的那些表征细胞在其他制剂。此外，GABA依赖性电导（gGABA）、逆转电位（EGABA）以及GABA与戊巴比妥和荷包牡丹碱的相互作用均正常。树突状GABA的应用可以引起去极化GABA反应，和体细胞GABA的应用引起超极化由于氯离子（Cl-）的运动。以0.5 Hz的频率重复短暂应用GABA（10（-5）至10（-3）M）（5-15 ms）导致IGABA连续峰的衰减，直到在给定的保持电位下达到稳定状态，其中IGABA不再变化。在稳态GABA反应的一系列过程中，施加持续数秒的电压阶跃最初导致增加的IGABA，然后随着阶跃电压的维持而减少。在每个新的保持电位的GABA的减少率是独立的极性的步骤保持电位，但高度依赖于GABA的应用率。低至0.05 Hz的施加速率导致IGABA的衰减，即使激活相对小的电导（5-15 nS）。由于在这些细胞中由体细胞GABA应用诱发的IGABA由Cl-携带，因此Cl-平衡电位（ECl）等于IGABA的逆转电位，即，到EGABA。随着保持电位的变化，IGABA的褪色几乎可以完全由Cl-通过GABA激活的电导的跨膜通量引起的ECl的转变来解释。防止细胞内Cl-离子浓度[Cl-]i变化的操作，包括在重复GABA应用期间将膜电位保持在EGABA或用高移液管[Cl-]缓冲[Cl-]i，可防止EGABA变化。在长时间应用GABA（大于1秒）期间，这些神经元中发生GABA反应的脱敏（gGABA的实际减少），但时间过程比GABA的变化慢。应用于组织培养的脊髓神经元的全细胞电压钳技术表明，在这些细胞中的GABA的重复应用，以及在GABA的快速变化的结果。（250字处删节）
The lability of the responses of mammalian central neurons to gamma-aminobutyric acid (GABA) was studied using neurons acutely dissociated from the CA1 region of the adult guinea pig hippocampus as a model system. GABA was applied to the neuronal somata by pressure ejection and the resulting current (IGABA) recorded under whole-cell voltage clamp. In initial experiments we examined several basic properties of cells in this preparation. Our data confirm that passive and active membrane properties are similar to those which characterize cells in other preparations. In addition, GABA-dependent conductance (gGABA), reversal potential (EGABA), and the interaction of GABA with pentobarbital and bicuculline all appeared to be normal. Dendritic GABA application could cause depolarizing GABA responses, and somatic GABA application caused hyperpolarizations due to chloride (Cl-) movements. Repetitive brief applications (5-15 ms) of GABA (10(-5) to 10(-3) M) at a frequency of 0.5 Hz led to fading of successive peaks of IGABA until, at a given holding potential, a steady state was reached in which IGABA no longer changed. Imposing voltage steps lasting seconds during a train of steady-state GABA responses led initially to increased IGABA that then diminished with maintenance of the step voltage. The rate of decrease of IGABA at each new holding potential was independent of the polarity of the step in holding potential but was highly dependent on the rate of GABA application. Application rates as low as 0.05 Hz led to fading of IGABA, even with activation of relatively small conductances (5-15 nS). Since IGABA evoked by somatic GABA application in these cells is carried by Cl-, the Cl- equilibrium potential (ECl) is equal to the reversal potential for IGABA, i.e., to EGABA. The fading of IGABA with changes in holding potential can be almost entirely accounted for by a shift in ECl resulting from transmembrane flux of Cl- through the GABA-activated conductance. Maneuvers that prevent changes in the intracellular concentration of Cl-ions, [Cl-]i, including holding the membrane potential at EGABA during repetitive GABA application or buffering [Cl-]i with high pipette [Cl-], prevent changes in EGABA. Desensitization of the GABA response (an actual decrease in gGABA) occurs in these neurons during prolonged application of GABA (greater than 1 s) but with a slower time course than changes in EGABA. Whole-cell voltage-clamp techniques applied to tissue-cultured spinal cord neurons indicated that rapid shifts in EGABA result from repetitive GABA application in these cells as well.(ABSTRACT TRUNCATED AT 250 WORDS)