Ca2+ activated K+-current density is correlated with soma size in rat vestibular-afferent neurons in culture
Ca2+ activated K+-current density is correlated with soma size in rat vestibular-afferent neurons in culture
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DOI：
10.1152/jn.00177.2005
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发表时间：
2005-12-01
影响因子：
2.5
通讯作者：
Soto, E
中科院分区：
文献类型：
--
作者：
Limón, A;Pérez, C;Soto, E
前庭传入神经元（VANs）在头部运动期间将有关线性和角加速度的信息从前庭终器传递到前庭核。在原位，这些神经元表现出不同的放电模式，这可能是由其内在特性的差异所导致的。然而，对于其不同放电模式背后的离子电流却知之甚少。我们利用全细胞膜片钳技术，分析了从幼鼠（出生后7 - 10天）分离的原代培养神经元中Ca²⁺和Ca²⁺激活的K⁺电流（I - KCa）的表达情况。我们发现根据低阈值Ca²⁺电流[低电压激活（LVA）]的表达情况，可将VANs分为两个有重叠的亚群；由小细胞组成的LVA（ - ）神经元，以及由中到大细胞组成的LVA（ + ）神经元。除了对经典阻断剂有抗性的通道（IR）外，两个细胞组中的I - KCa均通过高（BK）、中（IK）和低电导（SK）通道传导。BK优先在LVA（ + ）细胞中表达，而IR表达则优先在LVA（ - ）细胞中。未发现SK和IK的表达与胞体大小之间存在相关性。电流钳实验表明，BK参与放电的适应以及动作电位的持续时间，而SK和IK对培养的VANs的放电没有显著贡献。然而，由于在培养中具有重复放电的VANs数量较少，因此很难从放电模式的角度来解释我们的结果。我们的结果表明，前庭传入神经元具有不同的Ca²⁺激活的K⁺（K - Ca）通道，并且它们在细胞间的异质性表达有助于解释这些神经元电生理放电特性的一些差异。
Vestibular-afferent neurons (VANs) transmit information about linear and angular accelerations during head movements from vestibular end organs to vestibular nuclei. In situ, these neurons show heterogeneous discharge patterns that may be produced by differences in their intrinsic properties. However, little is known about the ionic currents underlying their different firing patterns. Using the whole cell patch-clamp technique, we analyzed the expression of Ca2+ and Ca2+-activated K+ currents (I-KCa) in primary cultured neurons isolated from young rats (p7-p10). We found two overlapping subpopulations of VANs classified according to low-threshold Ca2+-current [low-voltage -activated (LVA)] expression; LVA (-) neurons, formed by small cells, and LVA (+) neurons composed of medium to large cells. The I-KCa in both cell-groups was carried through channels of high (BK), intermediate (IK), and low conductance (SK), besides a resistant channel to classical blockers (IR). BK was expressed preferentially in LVA (+) cells, whereas IR expression was preferentially in LVA (-) cells. No correlation between SK and IK expression with the soma size was found. Current-clamp experiments showed that BK participates in the adaptation of discharge and in the duration of the action potential, whereas SK and IK did not show a significant contribution to electrical discharge of cultured VANs. However, because of the low number of VANs in culture with repetitive firing it is difficult to interpret our results in terms of discharge patterns. Our results demonstrate that vestibular-afferent neurons possess different Ca2+-activated K+ (K-Ca) channels and that their expression, heterogeneous among the cells, would contribute to explain some of the differences in the electrical-firing properties of these neurons.