Calcium dependence of exocytosis and endocytosis at the Cochlear inner hair cell afferent synapse
Calcium dependence of exocytosis and endocytosis at the Cochlear inner hair cell afferent synapse
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DOI：
10.1016/s0896-6273(01)00243-4
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发表时间：
2001-03-01
期刊：
影响因子：
16.2
通讯作者：
Moser, T
中科院分区：
文献类型：
--
作者：
Beutner, D;Voets, T;Moser, T
内毛细胞（IHS）传入突触处神经递质的释放是将声音转化为听觉神经兴奋的基本步骤。为了研究Ca 2+依赖性的基础囊泡融合和随后的内吞作用，我们结合了Ca 2 + uncaging与膜电容测量小鼠IHC。[Ca 2 +]（i）快速升高至8 μ M以上，导致双相电容增加，对应于类似于40，000个囊泡的融合。胞吐的动力学表现出五阶Ca 2+依赖性，达到>3 x 10（7）囊泡/s的最大速率。胞吐作用之后总是缓慢的、代偿性的胞吞作用（τ约为15秒）。更高的[Ca 2 +]（i）增加了贡献的一个更快的模式的内吞作用与Ca 2 +-独立的时间常数类似于300毫秒。这些属性提供了快速和持续的发射器释放从这个大的突触前终端。
Release of neurotransmitter at the inner hair cell (IHC) afferent synapse is a fundamental step in translating sound into auditory nerve excitation. To study the Ca2+ dependence of the underlying vesicle fusion and subsequent endocytosis, we combined Ca2+ uncaging with membrane capacitance measurements in mouse IHCs. Rapid elevations in [Ca2+](i) above 8 muM caused a biphasic capacitance increase corresponding to the fusion of similar to 40,000 vesicles. The kinetics of exocytosis displayed a fifth-order Ca2+ dependence reaching maximal rates of >3 x 10(7) vesicle/s. Exocytosis was always followed by slow, compensatory endocytosis (tau approximate to 15 s). Higher [Ca2+](i) increased the contribution of a faster mode of endocytosis with a Ca2+-independent time constant of similar to 300 ms. These properties provide for rapid and sustained transmitter release from this large presynaptic terminal.