Fast sodium channel gating supports localized and efficient axonal action potential initiation

Schmidt-Hieber, Christoph and Bischofberger, Josef. (2010) Fast sodium channel gating supports localized and efficient axonal action potential initiation. Journal of Neuroscience, 30 (30). pp. 10233-10242.

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Official URL: http://edoc.unibas.ch/dok/A6005842

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Action potentials (APs) are initiated in the proximal axon of most neurons. In myelinated axons, a 50-times higher sodium channel density in the initial segment compared to the soma may account for this phenomenon. However, little is known about sodium channel density and gating in proximal unmyelinated axons. To study the mechanisms underlying AP initiation in unmyelinated hippocampal mossy fibers of adult mice, we recorded sodium currents in axonal and somatic membrane patches. We demonstrate that sodium channel density in the proximal axon is approximately 5 times higher than in the soma. Furthermore, sodium channel activation and inactivation are approximately 2 times faster. Modeling revealed that the fast activation localized the initiation site to the proximal axon even upon strong synaptic stimulation, while fast inactivation contributed to energy-efficient membrane charging during APs. Thus, sodium channel gating and density in unmyelinated mossy fiber axons appear to be specialized for robust AP initiation and propagation with minimal current flow.
Faculties and Departments:03 Faculty of Medicine > Departement Biomedizin > Division of Physiology > Cellular Neurophysiology (Bischofberger)
UniBasel Contributors:Bischofberger, Josef
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Society for Neuroscience
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:27 Nov 2017 14:28
Deposited On:08 Nov 2012 16:20

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