Synaptic Vesicle Dynamics in Rat Fast and Slow Motor Nerve Terminals
Synaptic Vesicle Dynamics in Rat Fast and Slow Motor Nerve Terminals
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DOI：
10.1523/jneurosci.19-07-02511.1999
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发表时间：
1999-04
期刊：
影响因子：
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通讯作者：
B. Reid;C. Slater;G. Bewick
中科院分区：
文献类型：
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作者：
B. Reid;C. Slater;G. Bewick
我们已经调查了是否大鼠运动神经末梢在体内不同的活动模式也有不同的囊泡运输特性。为了做到这一点，我们监测，使用相结合的光学和电学技术，胞吐率（在不同的频率和活动模式），可释放池的大小，和突触囊泡在终端上比目鱼肌（慢收缩）和趾长伸肌[（EDL）;快收缩]肌纤维的再循环时间。终末的初始量子含量（QC）高于比目鱼肌，但在20-80 Hz的强直或相位刺激期间，终末QC比比目鱼肌QC下降更大程度。通过记录荧光损失的外泌囊泡标记的染料FM 1 -43，发现在比目鱼肌的EDL终端比那些褪色更快。同时细胞内记录终板电位，计数释放的囊泡的数量，允许估计总囊泡池（VP）的大小和回收时间相结合的光学和电生理数据。比目鱼肌囊泡池比双足肌囊泡池大，但再循环时间差异不显著。因此，这些终端，适应其在体内的活动模式，在QC和VP大小的改变，但不循环时间。
We have investigated whether rat motor nerve terminals with different in vivo activity patterns also have different vesicle trafficking characteristics. To do this, we monitored, using combined optical and electrical techniques, the rate of exocytosis (during different frequencies and patterns of activity), the releasable pool size, and the recycle time of synaptic vesicles in terminals on soleus (slow-twitch) and extensor digitorum longus [(EDL); fast-twitch] muscle fibers. EDL terminals had a higher initial quantal content (QC) than soleus, but during tonic or phasic stimulation at 20–80 Hz, EDL QC ran down to a greater extent than soleus QC. By recording loss of fluorescence from exocytosing vesicles labeled with the dye FM1–43, EDL terminals were found to destain faster than those in soleus. Simultaneous intracellular recording of end plate potentials, to count the number of vesicles released, permitted estimation of the total vesicle pool (VP) size and the recycle time by combining the optical and electrophysiological data. Soleus vesicle pool was larger than EDL, but recycle time was not significantly different. These terminals, therefore, are adapted to their in vivo activity patterns by alterations in QC and VP size but not recycle time.