Sodium‐dependent potassium channels of a Slack‐like subtype contribute to the slow afterhyperpolarization in lamprey spinal neurons
- 14 November 2007
- journal article
- Published by Wiley in The Journal of Physiology
- Vol. 585 (1), 75-90
- https://doi.org/10.1113/jphysiol.2007.138156
Abstract
The slow afterhyperpolarization (sAHP) following the action potential is the main determinant of spike frequency regulation. The sAHP after single action potentials in neurons of the lamprey locomotor network is largely due to calcium-dependent K+channels (80%), activated by calcium entering the cell during the spike. The residual (20%) component becomes prominent during high level activity (50% of the sAHP). It is not Ca2+ dependent, has a reversal potential like that of potassium, and is not affected by chloride injection. It is not due to rapid activation of Na+/K+-ATPase. This non-KCa-sAHP is reduced markedly in amplitude when sodium ions are replaced by lithium ions, and is thus sodium dependent. Quinidine also blocks this sAHP component, further indicating an involvement of sodium-dependent potassium channels (KNa). Modulators tested do not influence the KNa-sAHP amplitude. Immunofluorescence labelling with an anti-Slack antibody revealed distinct immunoreactivity of medium-sized and large neurons in the grey matter of the lamprey spinal cord, suggesting the presence of a Slack-like subtype of KNa channel. The results strongly indicate that a KNa potassium current contributes importantly to the sAHP and thereby to neuronal frequency regulation during high level burst activity as during locomotion. This is, to our knowledge, the first demonstration of a functional role for the Slack gene in contributing to the slow AHP.Keywords
This publication has 55 references indexed in Scilit:
- Characterization of Na+-Activated K+ Currents in Larval Lamprey Spinal Cord NeuronsJournal of Neurophysiology, 2007
- Localization of the Na+‐activated K+ channel Slick in the rat central nervous systemJournal of Comparative Neurology, 2005
- The motor infrastructure: from ion channels to neuronal networksNature Reviews Neuroscience, 2003
- Na+-Activated K+ Current Contributes to Postexcitatory Hyperpolarization in Neocortical Intrinsically Bursting NeuronsJournal of Neurophysiology, 2003
- The Sodium-Activated Potassium Channel Is Encoded by a Member of the Slo Gene FamilyNeuron, 2003
- Activity-Dependent Increase of the AHP Amplitude in T Sensory Neurons of the LeechJournal of Neurophysiology, 2002
- Changes in Electrophysiological Properties of Lamprey Spinal Motoneurons During Fictive SwimmingJournal of Neurophysiology, 2002
- Na+-activated K+ channels: a new family of large-conductance ion channelsTrends in Neurosciences, 1994
- Apamin blocks the slow AHP in lamprey and delays termination of locomotor burstsNeuroReport, 1992
- The Permeability of the Sodium Channel to Metal Cations in Myelinated NerveThe Journal of general physiology, 1972