Differential distribution of potassium channels in acutely demyelinated, primary-auditory neurons in vitro
Differential distribution of potassium channels in acutely demyelinated, primary-auditory neurons in vitro
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DOI：
10.1152/jn.1996.76.1.438
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发表时间：
1996-07-01
影响因子：
2.5
通讯作者：
Davis, RL
中科院分区：
文献类型：
--
作者：
Davis, RL
1. 对组织培养中维持的两个初级听觉神经元群进行钾通道活性的单通道记录。囊神经是金鱼第八脑神经的听觉成分，根据其周围神经支配模式分为两个分支。支配头端囊状黄斑的神经元对应于一类表现出尖峰频率适应的细胞。然而，支配尾部黄斑的神经元与另一种在体内表现出爆发性自发放电模式的细胞一致。通过显微解剖急性去除髓鞘后，对这些神经元类别的体细胞和节间轴突膜进行了研究。2。使用染料注射来区分神经元和髓磷脂膜。成功去除髓磷脂后，使用含有荧光黄的贴片电极填充神经元并揭示其在髓鞘内的形态。髓磷脂上的斑块导致神经元周围的雪旺细胞充满。3。根据单一电导、失活和对内部钙的敏感性观察和表征了四种钾通道。在两个神经元群体的体细胞膜和轴突膜上发现了三种电压依赖性 K+ 通道类型。两种通道类型表现出电压依赖性失活，平均电导分别为 32 和 19 pS，每种通道都具有独特的亚电导状态。第三类通道活动的电导估计为 12 pS，并且是非失活的。4．第四种类型的通道是 Ca2+ 激活的 K+ 通道 (k((Ca)))，根据其活性对其细胞质表面钙浓度的依赖性进行分类。与其他三种钾通道类型不同，这种通道仅在支配尾部感觉上皮的神经元上发现。与其他类型的钾通道一样，它在体细胞和轴突节间膜上都有发现。
1. Single-channel recordings of potassium channel activity were made from two populations of primary-auditory neurons maintained in tissue culture. The saccular nerve, which is the auditory component of the eighth cranial nerve in goldfish, was separated into two branches according to its peripheral innervation pattern. Neurons which innervated the rostral saccular macula corresponded to a class of cells that showed spike frequency adaptation; whereas, neurons which innervated the caudal macula were consistent with another type of cell that demonstrated bursting spontaneous firing patterns in vivo. Both somatic and internodal axonal membranes from each of these neuronal classes were studied after acute removal of the myelin sheath by microdissection.2. Dye injections were used to discriminate neuronal from myelin membrane. After successful removal of the myelin, patch electrodes containing Lucifer yellow were used to fill a neuron and reveal its morphology within the myelin sheath. Patches on myelin led to filling of Schwann cells that surrounded the neuron.3. Four kinds of potassium channels were observed and characterized according to unitary conductance, inactivation, and sensitivity to internal calcium. Three voltage-dependent K+ channel types were found on the somatic and axonal membrane of the two neuronal populations. Two channel types showed voltage-dependent inactivation and had average conductances of 32 and 19 pS, each with distinctive subconductance states. The third type of channel activity had an estimated conductance of 12 pS and was noninactivating.4. The fourth type of channel was the Ca2+-activated K+ channel (k((Ca))), which was classified by the dependence of its activity on the calcium concentration at its cytoplasmic surface. Unlike the other three potassium channel types, this kind of channel was found exclusively on neurons that innervated the caudal sensory epithelium. As with the other kinds of potassium channels, it was found on both somatic and axonal internodal membranes.