Dendritic Ca2+ transients evoked by action potentials in rat dorsal cochlear nucleus pyramidal and cartwheel neurons
Dendritic Ca2+ transients evoked by action potentials in rat dorsal cochlear nucleus pyramidal and cartwheel neurons
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DOI：
10.1152/jn.00709.2002
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发表时间：
2003-04-01
影响因子：
2.5
通讯作者：
Manis, PB
中科院分区：
文献类型：
--
作者：
Molitor, SC;Manis, PB
应用荧光成像和电生理同步记录技术，观察了耳蜗背核（DCN）锥体细胞（PC）和侧手翻细胞（CWC）树突内钙离子内流的变化。局部应用Cd 2+阻断PC和CWC树突中的Ca 2+瞬变，表明Ca 2+内流由树突状Ca 2+通道启动。在PC中，TTX消除了树突状Ca2+瞬变时，AP被完全阻断。然而，在AP的不完全阻断期间或当大的去极化替代阻断的AP时，Ca 2+内流可以部分恢复。在CWC，树突状Ca2+瞬变诱发的个别AP，或简单的尖峰，被TTX阻止，并可以恢复在一个不完整的块的AP或通过一个大的去极化。与此相反，树突状Ca2+瞬变诱发的复杂的尖峰，一个突发的AP叠加在一个缓慢的去极化，没有阻止TTX，尽管消除AP叠加在缓慢的去极化。这些结果表明两种不同的机制逆行激活树突状细胞钙通道：第一个需要快速Na+通道介导的AP或大的躯体去极化，而第二个是独立的Na+通道激活，只需要缓慢的去极化复杂的尖峰。
Simultaneous fluorescence imaging and electrophysiologic recordings were used to investigate the Ca2+ influx initiated by action potentials (APs) into dorsal cochlear nucleus (DCN) pyramidal cell (PC) and cartwheel cell (CWC) dendrites. Local application of Cd2+ blocked Ca2+ transients in PC and CWC dendrites, demonstrating that the Ca2+ influx was initiated by dendritic Ca2+ channels. In PCs, TTX eliminated the dendritic Ca2+ transients when APs were completely blocked. However, the Ca2+ influx could be partially recovered during an incomplete block of APs or when a large depolarization was substituted for the blocked APs. In CWCs, dendritic Ca2+ transients evoked by individual APs, or simple spikes, were blocked by TTX and could be recovered during an incomplete block of APs or by a large depolarization. In contrast, dendritic Ca2+ transients evoked by complex spikes, a burst of APs superimposed on a slow depolarization, were not blocked by TTX, despite eliminating the APs superimposed on the slow depolarization. These results suggest two different mechanisms for the retrograde activation of dendritic Ca2+ channels: the first requires fast Na+ channel-mediated APs or a large somatic depolarization, whereas the second is independent of Na+ channel activation, requiring only the slow depolarization underlying complex spikes.