Ultrafast exocytosis elicited by calcium current in synaptic terminals of retinal bipolar neurons
Ultrafast exocytosis elicited by calcium current in synaptic terminals of retinal bipolar neurons
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DOI：
10.1016/s0896-6273(00)80254-8
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发表时间：
1996-12-01
期刊：
影响因子：
16.2
通讯作者：
Matthews, G
中科院分区：
文献类型：
--
作者：
Mennerick, S;Matthews, G
使用高分辨率电容测量，我们已经表征了视网膜双极神经元带状突触终末的递质释放的超快成分。在去极化过程中，电容增加到约30fF的平台，时间常数约为1.5ms。当不受钙电流激活动力学的限制时，小池的耗尽速度更快，时间常数为0.5ms。在超快池耗尽后，电容以较慢的时间常数上升，约为300ms。EGTA(5 Mm)抑制了较慢的电容上升，但保持了超快相的完整性。BAPTA(5 MM)可抑制胞吐作用的两种成分。在双脉冲刺激下，超快成分从枯竭中恢复，其时间常数接近4 S。超快成分可能代表突触带底部停靠的小泡的融合，而较慢的成分代表突触带上更多的远端小泡。
Using high resolution capacitance measurements, we have characterized an ultrafast component of transmitter release in ribbon-type synaptic terminals of retinal bipolar neurons. During depolarization, capacitance increases to a plateau of similar to 30 fF with a time constant of similar to 1.5 ms. When not limited by activation kinetics of calcium current, the small pool is depleted even faster, with a time constant of 0.5 ms. After the ultrafast pool is depleted, capacitance rises with a slower time constant of similar to 300 ms. EGTA (5 mM) depresses the slower capacitance rise but leaves the ultrafast phase intact. BAPTA (5 mM) depresses both components of exocytosis. With paired-pulse stimulation, the ultrafast pool recovers from depletion with a time constant of similar to 4 s. The ultrafast component may represent fusion of docked vesicles at the base of the synaptic ribbon, while the slower component represents more distal vesicles on the ribbon.