Large-conductance calcium-activated potassium channels facilitate transmitter release in salamander rod synapse.
作者： J. W. Xu
DOI: 10.1523/JNEUROSCI.1572-05.2005
关键词:
摘要: Large-conductance calcium-activated potassium (BK) channels are colocalized with calcium at sites of exocytosis the presynaptic terminals throughout nervous system. It is expected that their activation would provide negative feedback to transmitter release, but opposite sometimes observed. Attempts resolve this apparent paradox based on alterations in action potential waveform have been ambiguous. In an alternative approach, we investigated influence channel neurotransmitter release a nonspiking neuron, salamander rod photoreceptors. Surprisingly, BK facilitates calcium-mediated from rods. The two form positive coupled loop. Calcium influx activates current, leading efflux increases current. normal physiological voltage range well matched dynamics When further depolarized, then hyperpolarizing current exceeds its facilitatory effect, causing truncation release. Thus, channel-BK linkage performs functions synapse: nonlinear potentiator and safety brake.
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