Evidence that Exocytosis Is Driven by Calcium Entry Through Multiple Calcium Channels in Goldfish Retinal Bipolar Cells
Evidence that Exocytosis Is Driven by Calcium Entry Through Multiple Calcium Channels in Goldfish Retinal Bipolar Cells
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DOI：
10.1152/jn.90881.2008
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发表时间：
2009-05-01
影响因子：
2.5
通讯作者：
Zenisek, David
中科院分区：
文献类型：
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作者：
Coggins, Michael;Zenisek, David
张建军，张建军，张建军，等。金鱼视网膜双极细胞中钙离子通过多种通道进入的证据。中国生物医学工程学报（英文版），2009。2009年2月25日首次出版；doi: 10.1152 / jn.90881.2008。含带状神经元代表神经细胞的一个子集，经历梯度膜去极化而不是Na+通道诱发动作电位。视网膜的双极细胞是一种含带神经元，广泛的研究已经证明了以钙依赖的方式释放和补充的动态不同的囊泡池。在这项研究中，我们观察了这些细胞中最快的可释放囊泡池的特性，通常被称为立即释放池（IRP），以研究囊泡释放与这些末端钙通道之间的关系。利用全细胞电容测量，我们监测了胞吐对不同幅度和持续时间的去极化的响应，重点是生理上相关的步骤去极化。我们发现IRP的释放速率随膜电位呈超线性增加，并且在膜电位的生理范围内，IRP以膜电位依赖的方式对EGTA浓度的升高敏感。我们的结果最好的解释是一个模型，其中多个Ca2+通道协同作用，以驱动单个突触囊泡的胞外分泌。汇集通过多个钙通道进入的钙对于减少与单个钙通道打开相关的神经递质释放的随机噪声可能是重要的。
Coggins M, Zenisek D. Evidence that exocytosis is driven by calcium entry through multiple calcium channels in goldfish retinal bipolar cells. J Neurophysiol 101: 2601-2619, 2009. First published February 25, 2009; doi:10.1152/jn.90881.2008. Ribbon-containing neurons represent a subset of neural cells that undergo graded membrane depolarizations rather than Na+-channel evoked action potentials. Bipolar cells of the retina are one type of ribbon-containing neuron and extensive research has demonstrated kinetically distinct pools of vesicles that are released and replenished in a calcium-dependent manner. In this study, we look at the properties of the fastest pool of releasable vesicles in these cells, often referred to as the immediately releasable pool (IRP), to investigate the relationships between vesicle release and calcium channels in these terminals. Using whole cell capacitance measurements, we monitored exocytosis in response to different magnitude and duration depolarizations, with emphasis on physiologically relevant step depolarizations. We find that release rate of the IRP increases superlinearly with membrane potential and that the IRP is sensitive to elevated EGTA concentrations in a membrane-potential-dependent manner across the physiological range of membrane potentials. Our results are best explained by a model in which multiple Ca2+ channels act in concert to drive exocytosis of a single synaptic vesicle. Pooling calcium entering through many calcium channels may be important for reducing stochastic noise in neurotransmitter release associated with the opening of individual calcium channels.