急性分离大鼠脑内神经元上由多巴胺引起的离子电流(英文)

Dopamine-induced ionic currents in acutely dissociated rat neurons of CNS

目的:研究多巴胺(DA)诱发神经元的电流反应。 方法:制霉菌素打孔的膜片箝全细胞记录。 结果:在-20mV箝制电压下,DA(0.1—1mmol·L^(-1))对26％黑质神经元(5/19个)引起外向电流;对36％海马CA_1锥体细胞(25/69个)出现3种反应:外向电流伴有膜电导增加、缓慢内向电流伴随膜电导减小、外向—内向电流。DA引起的CA_1锥体细胞电流反应的阈剂量为3mmol·L^(-1),无电压依赖关系。翻转电位(E_(DA))接近K^+平衡电位,为TEA抑制。结论:DA诱发海马CA_1锥体细胞的外向电流可能是K^+电流。

AIM : To determine whether or not the dopamine (DA) can induce ionic current in single neuron a-cutely dissociated from different central areas including striatum, ventral tegmental area (VTA) , substantia nigra pars compacta (SNC) and hip-pocampal CA1 area. METHODS: Using a new patch-clamp whole-cell recording technic, namely nystatin-perforated whole-cell configuration under voltage-clamp mode. RESULTS: In 36 single neurons isolated from the striatum and VTA, DA 10-1000 μmol·L-1 was quite diverse to elicit ionic current response. 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 (VH) 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 VH of - 20 mV. The concentration-response relationship of DA-induced currents showed the typical sigmoid shape with the threshold dose, being the maxium response dose are 3 μmol·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 (EDA) was close to the equilibrium potential of potassium (EK) calculated with the Nernst equation. TEA 5 mol·L-1 effectively inhibited the DA-induced response. CONCLUSION: These results suggest that DA-induced outward current is carried by K+ in single hippocampal CA1 pyramidal neuron.