Nakanishi K, Kukita F
Department of Physiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, Japan.
Brain Res. 2000 Apr 28;863(1-2):192-204. doi: 10.1016/s0006-8993(00)02152-1.
The influence of GABAergic neurons on spontaneous electrical activities of neocortical neurons in culture, which was estimated to be about 9.5% of the total neurons by immunohistochemistry, was examined using dual whole-cell recording. Synchronized depolarization or hyperpolarization was observed in recorded neurons with pipettes containing low [Cl(-)] solution, while synchronized bursting of action potentials (APs) was observed with pipettes containing high [Cl(-)] solution. Spontaneous currents (SCs) were synchronous in all pairs tested with either pipettes containing low or high [Cl(-)] solution and spontaneous outward currents (SOCs) observed at around -30 mV were sensitive to the GABA-A receptor antagonist, bicuculline. Their reversal potential (V(rev)) was linearly related to the logarithm of Cl(-) activity in the pipette (-56.9 mV/decade). The intracellular chloride concentration was estimated from the V(rev) of SCs with gramicidin perforated-patch recordings and was between 5.9 and 28.1 mM (mean: 13.0 mM). These results suggest that GABA depolarized some neurons and hyperpolarized others, depending on the E(Cl). Bicuculline decreased the frequency of periodic depolarized potentials and increased their amplitudes. However, perfusion with low [Cl(-)] bath solution did not decrease the frequency. Our data indicate that recurrent subthreshold electrical activities by GABAergic inputs along with glutamatergic inputs take part in deterring synchronized bursting and that intracellular [Cl(-)] can modulate this bursting.
利用双全细胞膜片钳记录技术，研究了γ-氨基丁酸能（GABAergic）神经元对培养的新皮质神经元自发电活动的影响，通过免疫组织化学估计其约占神经元总数的9.5%。当记录电极内灌流低[Cl⁻]溶液时，记录的神经元出现同步去极化或超极化；而当灌流高[Cl⁻]溶液时，则观察到动作电位（AP）的同步爆发。无论电极内灌流低[Cl⁻]还是高[Cl⁻]溶液，所有测试的神经元对之间的自发电流（SCs）都是同步的，且在约-30 mV时观察到的自发外向电流（SOCs）对GABA-A受体拮抗剂荷包牡丹碱敏感。其反转电位（V(rev)）与电极内Cl⁻活性的对数呈线性相关（-56.9 mV/十倍）。通过短杆菌肽穿孔膜片钳记录SCs的V(rev)来估计细胞内氯离子浓度，其范围在5.9至28.1 mM之间（平均：13.0 mM）。这些结果表明，GABA使一些神经元去极化，而使另一些神经元超极化，这取决于氯离子的平衡电位（E(Cl)）。荷包牡丹碱降低了周期性去极化电位的频率并增加了其幅度。然而，用低[Cl⁻]的浴液灌流并没有降低频率。我们的数据表明，GABA能输入与谷氨酸能输入一起产生的反复阈下电活动参与了抑制同步爆发，并且细胞内[Cl⁻]可以调节这种爆发。
