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J Physiol. 2008 Oct 15;586(20):4877-90. doi: 10.1113/jphysiol.2008.155762. Epub 2008 Aug 21.

ERG voltage-gated K+ channels regulate excitability and discharge dynamics of the medial vestibular nucleus neurones.

Author information

1
Department of Internal Medicine, Section of Human Physiology, University of Perugia, Perugia, Italy. pessia@unipg.it

Abstract

The discharge properties of the medial vestibular nucleus neurones (MVNn) critically depend on the activity of several ion channel types. In this study we show, immunohistochemically, that the voltage-gated K(+) channels ERG1A, ERG1B, ERG2 and ERG3 are highly expressed within the vestibular nuclei of P10 and P60 mice. The role played by these channels in the spike-generating mechanisms of the MVNn and in temporal information processing was investigated electrophysiologically from mouse brain slices, in vitro, by analysing the spontaneous discharge and the response to square-, ramp- and sinusoid-like intracellular DC current injections in extracellular and whole-cell patch-clamp studies. We show that more than half of the recorded MVNn were responsive to ERG channel block (WAY-123,398, E4031), displaying an increase in spontaneous activity and discharge irregularity. The response to step and ramp current injection was also modified by ERG block showing a reduction of first spike latency, enhancement of discharge rate and reduction of the slow spike-frequency adaptation process. ERG channels influence the interspike slope without affecting the spike shape. Moreover, in response to sinusoid-like current, ERG channel block caused frequency-dependent gain enhancement and phase-lead shift. Taken together, the data demonstrate that ERG channels control the excitability of MVNn, their discharge regularity and probably their resonance properties.

PMID:
18718985
PMCID:
PMC2614050
DOI:
10.1113/jphysiol.2008.155762
[Indexed for MEDLINE]
Free PMC Article

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