Characterization of TTX-resistant persistent Na+ current underlying pacemaker potentials of fish gonadotropin-releasing hormone (GnRH) neurons.
Characterization of TTX-resistant persistent Na+ current underlying pacemaker potentials of fish gonadotropin-releasing hormone (GnRH) neurons.
复制标题
鱼促性腺激素释放激素 (GnRH) 神经元起搏器电位的 TTX 抗性持续 Na 电流的表征。
DOI：
10.1152/jn.1996.75.6.2397
复制
发表时间：
1996
影响因子：
2.5
通讯作者：
Y. Oka
中科院分区：
文献类型：
--
作者：
Y. Oka
1.内源性起搏活动对于促性腺激素释放激素（GnRH）免疫反应终末神经（TN）细胞的神经调节功能是重要的。以前，我们已经表明，通过电流钳分析，河豚毒素（TTX）的耐持续性Na+电流，INa（慢），起着重要的作用，在TN-GnRH细胞的起搏电位的产生。本研究采用全细胞膜片钳技术，在离体全脑标本上研究了INa（慢）的电生理特性。2. TN-GnRH细胞位于腹侧脑膜的正下方;因此，通过轻轻去除脑膜，可以暴露和观察细胞。通过阻断K+电流、Ca 2+电流和常规快Na+电流，间接分离INa（慢）电流。3. INa（慢）的特点是对TTX阻断的抗性，对外部Na+的依赖性，缓慢激活，非常缓慢和几乎没有失活，以及在静息电位附近激活和失活曲线的广泛重叠。这些特征与传统的快Na+电流不同，并且与TN-GnRH细胞的起搏活性所需的持续内向电流的产生有关。
1. Endogenous pacemaker activities are important for the putative neuromodulator functions of the gonadotropin-releasing hormone (GnRH)-immunoreactive terminal nerve (TN) cells. Previously we have shown by current-clamp analysis that a tetrodotoxin (TTX)-resistant persistent Na+ current, INa(slow), plays an important role in the generation of pacemaker potentials of TN-GnRH cells. The present study investigates electrophysiological characteristics of INa(slow) by using the whole cell patch-clamp technique in in vitro whole-brain preparation of a small fish brain. 2. TN-GnRH cells lie immediately beneath the ventral meningeal membrane; the cells could thus be exposed and visualized by gently removing the meningeal membrane. INa(slow) currents were isolated pharmacologically by blocking K+ currents, Ca2+ currents, and conventional fast Na+ currents. 3. INa(slow) was characterized by resistance to TTX blockade, dependence on external Na+, slow activation, very slow and little inactivation, and wide overlap of activation and inactivation curves near the resting potential. These characteristics are distinct from those of conventional fast Na+ current, and are relevant for the generation of persistent inward currents necessary for the pacemaker activity of TN-GnRH cells.