The Frog Motor Nerve Terminal Has Very Brief Action Potentials and Three Electrical Regions Predicted to Differentially Control Transmitter Release
The Frog Motor Nerve Terminal Has Very Brief Action Potentials and Three Electrical Regions Predicted to Differentially Control Transmitter Release
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DOI：
10.1523/jneurosci.2415-19.2020
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发表时间：
2020-04-29
影响因子：
5.3
通讯作者：
Meriney, Stephen D.
中科院分区：
文献类型：
--
作者：
Ginebaugh, Scott P.;Cyphers, Eric D.;Meriney, Stephen D.
动作电位（AP）波形控制电压门控钙通道的开放，并有助于钙离子流的驱动力，触发突触前神经末梢的神经传递。虽然青蛙神经肌肉接头（NMJ）长期以来一直是研究神经传递的模型突触，但其突触前AP波形从未被直接研究过，因此AP波形的形状和通过这个长的突触前神经末梢的传播是未知的。使用快速电压敏感染料，我们已经成像的AP波形从突触前终端的男性和女性青蛙NMJ和显示，AP是非常短暂的持续时间和积极传播沿着整个长度的终端。此外，基于测量的AP波形在不同区域沿着的长度的神经末梢，我们表明，终端被分为三个不同的电区域：一个开始区域后，最后一个节点的AP是最广泛的，一个中间区域与一个相对一致的AP持续时间，和一个结束区域附近的尖端的神经末梢分支的AP是briefer。我们假设，这些测量的AP波形沿着运动神经末梢的长度的变化可以解释近端-远端梯度的发射器释放先前报告的青蛙NMJ。
The action potential (AP) waveform controls the opening of voltage-gated calcium channels and contributes to the driving force for calcium ion flux that triggers neurotransmission at presynaptic nerve terminals. Although the frog neuromuscular junction (NMJ) has long been a model synapse for the study of neurotransmission, its presynaptic AP waveform has never been directly studied, and thus the AP waveform shape and propagation through this long presynaptic nerve terminal are unknown. Using a fast voltage-sensitive dye, we have imaged the AP waveform from the presynaptic terminal of male and female frog NMJs and shown that the AP is very brief in duration and actively propagated along the entire length of the terminal. Furthermore, based on measured AP waveforms at different regions along the length of the nerve terminal, we show that the terminal is divided into three distinct electrical regions: A beginning region immediately after the last node of Ranvier where the AP is broadest, a middle region with a relatively consistent AP duration, and an end region near the tip of nerve terminal branches where the AP is briefer. We hypothesize that these measured changes in the AP waveform along the length of the motor nerve terminal may explain the proximal-distal gradient in transmitter release previously reported at the frog NMJ.