Low-voltage-activated potassium channels underlie the regulation of intrinsic firing properties of rat vestibular ganglion cells
Low-voltage-activated potassium channels underlie the regulation of intrinsic firing properties of rat vestibular ganglion cells
复制标题
DOI：
10.1152/jn.01240.2007
复制
发表时间：
2008-10-01
影响因子：
2.5
通讯作者：
Sahara, Yoshinori
中科院分区：
文献类型：
--
作者：
Iwasaki, Shinichi;Chihara, Yasuhiro;Sahara, Yoshinori
个体初级前庭传入表现出自发活动，其规律性可以从规则到不规则变化。前庭反应的不同方面与静息放电的规律性有关。分离的大鼠前庭神经节细胞（VGC）在持续膜去极化期间表现出不均匀的内在放电特性：一些神经元表现出强烈的适应，仅产生单个或几个棘波（阶段型），而其他神经元则表现出中度适应或强直性放电（强直型）。紧张性放电的VGC在出生后5-7天是罕见的，在出生后2-3周增加到接近60%的神经元。为了探讨初级前庭传入神经放电规律的主要因素，我们研究了K+通道对离体大鼠VGC放电特性的影响。在4-氨基吡啶或α-树毒素的存在下，时相放电变为强直放电，表明Kv 1钾通道控制时相VGC的放电模式。四乙铵减少了在所有类型的阶跃电流刺激过程中的尖峰的数量。阻断Ca ~（2+）激活的K ~+通道可减少紧张性VGC的峰电位数目。我们的研究结果表明，Kv 1通道是至关重要的，在确定模式的尖峰放电在大鼠前庭神经节神经元，并在其成熟过程中的比例变化。
Individual primary vestibular afferents exhibit spontaneous activity the regularity of which can vary from regular to irregular. Different aspects of vestibular responsiveness have been associated with this dimension of regularity of resting discharge. Isolated rat vestibular ganglion cells (VGCs) showed heterogeneous intrinsic firing properties during sustained membrane depolarization: some neurons exhibited a strong adaptation generating just a single or a few spikes (phasic type), whereas other neurons showed moderate adaptation or tonic firing (tonic type). Tonic discharging VGCs were rare at postnatal days 5-7 and increased up to similar to 60% of neurons during postnatal 2-3 wk. To explore the major factors responsible for the discharge regularity of primary vestibular afferents, we investigated the contribution of K+ channels to the firing properties of isolated rat VGCs. Phasic firing became tonic firing in the presence of 4-aminopyridine or alpha-dendrotoxin, indicating that Kv1 potassium channels control the firing pattern of the phasic VGCs. Tetraethylammonium decreased the number of spikes during step current stimuli in all types. Blockade of Ca2+-activated K+ channels decreased the number of spikes in tonic VGCs. Our results suggest that Kv1 channels are critical both in determining the pattern of spike discharge in rat vestibular ganglion neurons and in their proportional change during maturation.