Development of inward rectification and control of membrane excitability in mesencephalic v neurons.
Development of inward rectification and control of membrane excitability in mesencephalic v neurons.
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DOI：
10.1152/jn.00850.2002
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发表时间：
2003-03
影响因子：
2.5
通讯作者：
Susumu Tanaka;Nanping Wu;C. Hsaio;J. Turman;S. H. Chandler
中科院分区：
文献类型：
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作者：
Susumu Tanaka;Nanping Wu;C. Hsaio;J. Turman;S. H. Chandler
本研究旨在评估大鼠中脑三叉神经元（Mes V）神经元的出生后发育和内向整流电流的功能作用，这些神经元参与口腔运动活动的发生和控制。从脑干切片中的 Mes V 神经元获得的全细胞电压钳记录识别出快速 (I(KIR)) 和慢速 (I(h)) 内向整流电流，这些电流分别被 BaCl(2) (300-500 microM) 或 4-(N-乙基-N-苯氨基)-1,2-二甲基-6-(甲基氨基) 氯化嘧啶 (ZD 7288, 10 microM) 特异性阻断。这些通道的全细胞电流密度在出生后 2 至 12 天 (P2-P12) 之间增加，并且 I(h) 激活和失活的时间进程分别由两个时间常数很好地描述。 ZD 7288 的应用在大多数细胞中产生膜超极化和延长的超极化后复极化。此外，在 ZD 7288 存在的情况下，尖峰频率降低，适应性更加明显。有趣的是，这些神经元表现出电压依赖性膜共振（<10 Hz），这种共振在静息电位周围很突出，对静息更不利，并被 ZD 7288 阻断。这些结果表明 I(h) 有助于稳定静息膜电位和控制细胞兴奋性。 I(h)的存在赋予神经元独特的低频膜共振性质；根据频率内容区分突触输入的能力。
The present study was performed to assess the postnatal development and functional roles of inward rectifying currents in rat mesencephalic trigeminal (Mes V) neurons, which are involved in the genesis and control of oral-motor activities. Whole cell voltage-clamp recordings obtained from Mes V neurons in brain stem slices identified fast (I(KIR)) and slow (I(h)) inward rectifying currents, which were specifically blocked by BaCl(2) (300-500 microM) or 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyrimidinium chloride (ZD 7288, 10 microM), respectively. The whole cell current density for these channels increased between postnatal days 2 to 12 (P2-P12), and the time courses for I(h) activation and deactivation were each well described by two time constants. Application of ZD 7288 produced membrane hyperpolarization in the majority of cells and prolonged afterhyperpolarization repolarization. Additionally, in the presence of ZD 7288, spike frequency was decreased and adaptation was more pronounced. Interestingly, these neurons exhibited a voltage-dependent membrane resonance (<10 Hz) that was prominent around resting potential and more negative to rest and was blocked by ZD 7288. These results suggest that I(h) contributes to stabilizing resting membrane potential and controlling cell excitability. The presence of I(h) imparts the neuron with the unique property of low-frequency membrane resonance; the ability to discriminate between synaptic inputs based on frequency content.