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Cell Rep. 2015 Sep 22;12(11):1715-22. doi: 10.1016/j.celrep.2015.08.022. Epub 2015 Sep 3.

Calcium-Activated Potassium Channels at Nodes of Ranvier Secure Axonal Spike Propagation.

Author information

1
Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.
2
Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK. Electronic address: b.clark@ucl.ac.uk.

Abstract

Functional connectivity between brain regions relies on long-range signaling by myelinated axons. This is secured by saltatory action potential propagation that depends fundamentally on sodium channel availability at nodes of Ranvier. Although various potassium channel types have been anatomically localized to myelinated axons in the brain, direct evidence for their functional recruitment in maintaining node excitability is scarce. Cerebellar Purkinje cells provide continuous input to their targets in the cerebellar nuclei, reliably transmitting axonal spikes over a wide range of rates, requiring a constantly available pool of nodal sodium channels. We show that the recruitment of calcium-activated potassium channels (IK, K(Ca)3.1) by local, activity-dependent calcium (Ca(2+)) influx at nodes of Ranvier via a T-type voltage-gated Ca(2+) current provides a powerful mechanism that likely opposes depolarizing block at the nodes and is thus pivotal to securing continuous axonal spike propagation in spontaneously firing Purkinje cells.

PMID:
26344775
PMCID:
PMC4590545
DOI:
10.1016/j.celrep.2015.08.022
[Indexed for MEDLINE]
Free PMC Article

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