Characterization of K+ currents underlying pacemaker potentials of fish gonadotropin-releasing hormone cells.
Characterization of K+ currents underlying pacemaker potentials of fish gonadotropin-releasing hormone cells.
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鱼类促性腺激素释放激素细胞起搏器电位的 K 电流特征。
DOI：
10.1152/jn.1999.81.2.643
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发表时间：
1999
影响因子：
2.5
通讯作者：
Y. Oka
中科院分区：
文献类型：
--
作者：
H. Abe;Y. Oka
内源性起搏器活性对于促性腺激素释放激素 (GnRH) 免疫反应性终末神经 (TN) 细胞的假定神经调节功能非常重要。我们分析了几种类型的电压依赖性 K+ 电流，以研究 TN-GnRH 细胞起搏器电位复极相的离子机制，方法是使用鱼（矮吻鲈、Colisa lalia）的全脑体外制备物。 TN-GnRH 细胞至少具有四种类型的电压依赖性 K+ 电流：1) 4-氨基吡啶 (4AP) 敏感 K+ 电流，2) 四乙铵 (TEA) 敏感 K+ 电流，以及 3) 和 4) 两种类型的 TEA 抗性和 4AP 抗性 K+ 电流。从 -100 mV 的保持电位诱发瞬时、低阈值 K+ 电流，该电流对 4AP 敏感，并在生理膜电位范围（-40 至 -60 mV）内表现出显着的稳态失活。因此，该电流不会导致起搏器电位的复极阶段。由-100 mV的保持电位引起的TEA敏感的K+电流缓慢激活、持续时间长，并且表现出相对较低的激活阈值。该电流在 -60 至 -40 mV 的稳态（相当于静息膜电位）下仅部分失活。 TEA 和 4AP 抗性持续 K+ 电流是从 -100 mV 的保持电位引起的，根据激活曲线的分析，建议由两种类型组成。从失活和激活曲线来看，激活阈值较低的其中之一可能部分参与起搏器电位的复极阶段。 TEA 与河豚毒素一起浴应用可逆地阻断电流钳记录中的起搏器电位。我们得出的结论是，TEA 敏感的 K+ 电流最有可能有助于 TN-GnRH 细胞起搏器电位的复极化阶段。
Endogenous pacemaker activities are important for the putative neuromodulator functions of the gonadotropin-releasing hormone (GnRH)-immunoreactive terminal nerve (TN) cells. We analyzed several types of voltage-dependent K+ currents to investigate the ionic mechanisms underlying the repolarizing phase of pacemaker potentials of TN-GnRH cells by using the whole brain in vitro preparation of fish (dwarf gourami, Colisa lalia). TN-GnRH cells have at least four types of voltage-dependent K+ currents: 1) 4-aminopyridine (4AP)-sensitive K+ current, 2) tetraethylammonium (TEA)-sensitive K+ current, and 3) and 4) two types of TEA- and 4AP-resistant K+ currents. A transient, low-threshold K+ current, which was 4AP sensitive and showed significant steady-state inactivation in the physiological membrane potential range (-40 to -60 mV), was evoked from a holding potential of -100 mV. This current thus cannot contribute to the repolarizing phase of pacemaker potentials. TEA-sensitive K+ current evoked from a holding potential of -100 mV was slowly activating, long lasting, and showed comparatively low threshold of activation. This current was only partially inactivated at steady state of -60 to -40 mV, which is equivalent to the resting membrane potential. TEA- and 4AP-resistant sustained K+ currents were evoked from a holding potential of -100 mV and were suggested to consist of two types, based on the analysis of activation curves. From the inactivation and activation curves, it was suggested that one of them with low threshold of activation may be partly involved in the repolarizing phase of pacemaker potentials. Bath application of TEA together with tetrodotoxin reversibly blocked the pacemaker potentials in current-clamp recordings. We conclude that the TEA-sensitive K+ current is the most likely candidate that contributes to the repolarizing phase of the pacemaker potentials of TN-GnRH cells.
影响因子：
2.5
作者：
Gold, MS;Shuster, MJ;Levine, JD
通讯作者：
Levine, JD