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首页> 外文期刊>The Journal of Neuroscience: The Official Journal of the Society for Neuroscience >Large-conductance calcium-activated potassium channels facilitate transmitter release in salamander rod synapse.
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Large-conductance calcium-activated potassium channels facilitate transmitter release in salamander rod synapse.

机译:大电导钙激活的钾离子通道促进sal棒突触中的递质释放。

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摘要

Large-conductance calcium-activated potassium (BK) channels are colocalized with calcium channels at sites of exocytosis at the presynaptic terminals throughout the nervous system. It is expected that their activation would provide negative feedback to transmitter release, but the opposite is sometimes observed. Attempts to resolve this apparent paradox based on alterations in action potential waveform have been ambiguous. In an alternative approach, we investigated the influence of this channel on neurotransmitter release in a nonspiking neuron, the salamander rod photoreceptors. Surprisingly, the BK channel facilitates calcium-mediated transmitter release from rods. The two presynaptic channels form a positive coupled loop. Calcium influx activates the BK channel current, leading to potassium efflux that increases the calcium current. The normal physiological voltage range of the rod is well matched to the dynamics of this positive loop. When the rod is further depolarized, then the hyperpolarizing BK channel current exceeds its facilitatory effect, causing truncation of transmitter release. Thus, the calcium channel-BK channel linkage performs two functions at the synapse: nonlinear potentiator and safety brake.
机译:大电导的钙激活钾(BK)通道与钙通道在整个神经系统突触前末端的胞吐作用位点处共定位。预期它们的激活将为发射器的释放提供负面反馈,但有时会观察到相反的情况。试图解决基于动作电位波形变化的这种明显的矛盾是模棱两可的。在另一种方法中,我们研究了该通道对不加尖刺的神经元,棒光感受器中神经递质释放的影响。出人意料的是,BK通道促进了钙介导的递质从棒中释放。两个突触前通道形成正耦合环。钙流入激活BK通道电流,导致钾流出,从而增加钙电流。杆的正常生理电压范围与该正回路的动力学很好地匹配。当棒进一步去极化时,超极化BK通道电流超过其促进作用,导致发射器释放被截断。因此,钙通道-BK通道联动在突触中执行两个功能:非线性增强器和安全制动。

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