Functional roles of Kv1 channels in neocortical pyramidal neurons

Dongxu Guan, J. C F Lee, M. H. Higgs, W. J. Spain, Robert Foehring

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Abstract

Pyramidal neurons from layers II/III of somatosensory and motor cortex express multiple Kv1 α-subunits and a current sensitive to block by α-dendrotoxin (α-DTX). We examined functional roles of native Kv1 channels in these cells using current-clamp recordings in brain slices and current- and voltage-clamp recordings in dissociated cells. α-DTX caused a significant negative shift in voltage threshold for action potentials (APs) and reduced rheobase. Correspondingly, a ramp-voltage protocol revealed that the α-DTX-sensitive current activated at subthreshold voltages. AP width at threshold increased with successive APs during repetitive firing. The steady-state threshold width for a given firing rate was similar in control and α-DTX, despite an initially broader AP in α-DTX. AP voltage threshold increased similarly during a train of spikes under control conditions and in the presence of α-DTX. α-DTX had no effect on input resistance or resting membrane potential and modest effects on the amplitude or width of a single AP. Accordingly, experiments using AP waveforms (APWs) as voltage protocols revealed that α-DTX-sensitive current peaked late during the AP repolarization phase. Application of α-DTX increased the rate of firing to intracellular current injection and increased gain (multiplicative effects), but did not alter spike-frequency adaptation. Consistent with these findings, voltage-clamp experiments revealed that the proportion of outward current sensitive to α-DTX was highest during the interval between two APWs, reflecting slow deactivation kinetics at -50 mV. Finally, α-DTX did not alter the selectivity of pyramidal neurons for DC versus time-varying stimuli.

Original languageEnglish (US)
Pages (from-to)1931-1940
Number of pages10
JournalJournal of Neurophysiology
Volume97
Issue number3
DOIs
StatePublished - Mar 1 2007

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Pyramidal Cells
Action Potentials
Architectural Accessibility
Somatosensory Cortex
Motor Cortex
Membrane Potentials
Injections
Brain

All Science Journal Classification (ASJC) codes

  • Physiology
  • Neuroscience(all)

Cite this

Functional roles of Kv1 channels in neocortical pyramidal neurons. / Guan, Dongxu; Lee, J. C F; Higgs, M. H.; Spain, W. J.; Foehring, Robert.

In: Journal of Neurophysiology, Vol. 97, No. 3, 01.03.2007, p. 1931-1940.

Research output: Contribution to journalArticle

Guan, Dongxu ; Lee, J. C F ; Higgs, M. H. ; Spain, W. J. ; Foehring, Robert. / Functional roles of Kv1 channels in neocortical pyramidal neurons. In: Journal of Neurophysiology. 2007 ; Vol. 97, No. 3. pp. 1931-1940.
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