Differential expression of three distinct potassium currents in the ventral cochlear nucleus

J Neurophysiol. 2003 Jun;89(6):3070-82. doi: 10.1152/jn.00125.2002.


In the ventral cochlear nucleus (VCN), neurons transform information from auditory nerve fibers into a set of parallel ascending pathways, each emphasizing different aspects of the acoustic environment. Previous studies have shown that VCN neurons differ in their intrinsic electrical properties, including the K+ currents they express. In this study, we examine these K+ currents in more detail using whole cell voltage-clamp techniques on isolated VCN cells from adult guinea pigs at 22 degrees C. Our results show a differential expression of three distinct K+ currents. Whereas some VCN cells express only a high-threshold delayed-rectifier-like current (IHT), others express IHT in combination with a fast inactivating current (IA) and/or a slow-inactivating low-threshold current (ILT). IHT, ILT, and IA, were partially blocked by 1 mM 4-aminopyridine. In contrast, only ILT was blocked by 10-100 nM dendrotoxin-I. A surprising finding was the wide range of levels of ILT, suggesting ILT is expressed as a continuum across cell types rather than modally in a particular cell type. IA, on the other hand, appears to be expressed only in cells that show little or no ILT, the Type I cells. Boltzmann analysis shows IHT activates with 164 +/- 12 (SE) nS peak conductance, -14.3 +/- 0.7 mV half-activation, and 7.0 +/- 0.5 mV slope factor. Similar analysis shows ILT activates with 171 +/- 22 nS peak conductance, -47.4 +/- 1.0 mV half-activation, and 5.8 +/- 0.3 mV slope factor.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 4-Aminopyridine / pharmacology
  • Animals
  • Brain Stem / physiology
  • Cell Culture Techniques
  • Cochlear Nucleus / cytology
  • Cochlear Nucleus / drug effects
  • Cochlear Nucleus / physiology*
  • Elapid Venoms / pharmacology
  • Guinea Pigs
  • Neurons / drug effects
  • Neurons / physiology*
  • Patch-Clamp Techniques
  • Potassium Channel Blockers / pharmacology
  • Potassium Channels / drug effects
  • Potassium Channels / physiology*


  • Elapid Venoms
  • Potassium Channel Blockers
  • Potassium Channels
  • dendrotoxin
  • 4-Aminopyridine