Sodium pump regulation of locomotor control circuits
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Sodium pumps are ubiquitously expressed membrane proteins that extrude three Na+ ions in exchange for two K+ ions using ATP as an energy source. Recent studies have illuminated additional, dynamic roles for sodium pumps in regulating the excitability of neuronal networks in an activity-dependent fashion. Here we review their role in a novel form of short-term memory within rhythmic locomotor networks. The data we review derives mainly from recent studies on Xenopus tadpoles and neonatal mice. The role and underlying mechanisms of pump action broadly match previously published data from an invertebrate, the Drosophila larva. We therefore propose a highly conserved mechanism by which sodium pump activity increases following a bout of locomotion. This results in an ultraslow afterhyperpolarisation (usAHP) of the membrane potential that lasts around 1 minute, but which only occurs in around half the network neurons. This usAHP in turn alters network excitability so that network output is reduced in a locomotor interval-dependent manner. The pumps therefore confer on spinal locomotor networks a temporary memory trace of recent network performance.
Picton , L D , Zhang , H & Sillar , K T 2017 , ' Sodium pump regulation of locomotor control circuits ' , Journal of Neurophysiology , vol. 118 , no. 2 , pp. 1070-1081 . https://doi.org/10.1152/jn.00066.2017
Journal of Neurophysiology
Copyright © 2017, Journal of Neurophysiology. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1152/jn.00066.2017
DescriptionThe authors are grateful for the financial support of the BBSRC (grant numbers: BB/M024946/1 and BB/JO1446X/1), the Carnegie Trust and the University of St Andrews.
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