Wu J, Chen P X, Jin G Z
Department of Physiology, Sun Yat-Sen University of Medical Sciences, Guangzhou, China.
Zhongguo Yao Li Xue Bao. 1996 Jan;17(1):23-7.
To determine whether or not the dopamine (DA) can induce ionic current in single neuron acutely dissociated from different central areas including striatum, ventral tegmental area (VTA), substantia nigra pars compacta (SNC) and hippocampal CA1 area.
Using a new patch-clamp whole-cell recording technic, namely nystatin-perforated whole-cell configuration under voltage-clamp mode.
In 36 single neurons isolated from the striatum and VTA, DA 10-1000 mumol.L-1 was quite diverse to elicit ionic current responses. In 19 SNC neurons, 5 neurons (26%) response to 1 mmol.L-1 DA represented as a small outward current (11.3 +/- 2.4 pA) at a holding potential (V(H)) of -20 mV. In 25 of 69 (36%) examined hippocampal CA1 pyramidal neurons, however, application of DA induced 3 types of current responses: outward current (8 neurons) accompanied with an increase of membrane conductance, slow inward current (5 neurons) with an decrease of membrane conductance and outward-following inward current (12 neurons) at a V(H) of -20 mV. The concentration-response relationship of DA-induced currents showed the typical sigmoid shape with the threshold dose, being the maximum response dose are 3 mumol.L-1 and 1 mmol.L-1 respectively. The current-voltage (I-V) relationship of DA-induced responses did not show any voltage-dependent manner and the reversal potential (E(DA)) was close to the equilibrium potential of potassium (E(K)) calculated with the Nernst equation. TEA 5 mol.L-1 effectively inhibited the DA-induced response.
These results suggest that DA-induced outward current is carried by K+ in single hippocampal CA1 pyramidal neuron.
确定多巴胺（DA）能否在急性分离自包括纹状体、腹侧被盖区（VTA）、黑质致密部（SNC）和海马CA1区等不同中枢区域的单个神经元中诱导离子电流。
采用一种新的膜片钳全细胞记录技术，即在电压钳模式下的制霉菌素穿孔全细胞配置。
在从纹状体和VTA分离的36个单个神经元中，10 - 1000 μmol·L-1的DA引发离子电流反应的情况差异很大。在19个SNC神经元中，5个神经元（26%）对1 mmol·L-1 DA有反应，在 - 20 mV的钳制电位（V(H)）下表现为小的外向电流（11.3±2.4 pA）。然而，在69个被检测的海马CA1锥体神经元中的25个（36%）中，应用DA诱导出3种电流反应：外向电流（8个神经元）伴有膜电导增加、内向慢电流（5个神经元）伴有膜电导降低以及在 - 20 mV的V(H)下的外向跟随内向电流（12个神经元）。DA诱导电流的浓度 - 反应关系呈典型的S形，阈值剂量分别为3 μmol·L-1和最大反应剂量为1 mmol·L-。DA诱导反应的电流 - 电压（I - V）关系未显示出任何电压依赖性方式，反转电位（E(DA)）接近用能斯特方程计算的钾平衡电位（E(K)）。5 mol·L-1的四乙铵（TEA）有效抑制了DA诱导的反应。
这些结果表明，在单个海马CA1锥体神经元中，DA诱导的外向电流由K+携带。
