Potassium currents in presynaptic hair cells of Hermissenda

Ebenezer N. Yamoah

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Apart from their primary function as balance sensors, Hermissenda hair cells are presynaptic neurons involved in the Ca2+ -dependent neuronal plasticity in postsynaptic B photoreceptors that accompanies classical conditioning. With a view to beginning to understand presynaptic mechanisms of plasticity in the vestibulo-visual system, a locus for conditioning- induced neuronal plasticity, outward currents that may govern the excitability of hair cells were recorded by means of a whole-cell patch- clamp technique. Three K+ currents were characterized: a 4-aminopyridine- sensitive transient outward K+ current (I(A)), a tetraethyl ammonium- sensitive delayed rectifier K+ current (I(K,V)), and a Ca2+-activated K+ current (I(K,Ca)). I(A) activates and decays rapidly; the steady-state activation and inactivation curves of the current reveal a window current close to the apparent resting voltage of the hair cells, suggesting that the current is partially activated at rest. By modulating firing frequency and perhaps damping membrane oscillations, I(A) may regulate synaptic release at baseline. In contrast, I(K,V) and I(K,Ca) have slow onset and exhibit little or no inactivation. These two K+ currents may determine the duration of the repolarization phase of hair-cell action potentials and hence synaptic release via Ca2+ influx through voltage-gated Ca2+ channels. In addition, I(K,Ca) may be responsible for the afterhyperpolarization of hair cell membrane voltage following prolonged stimulation.

Original languageEnglish (US)
Pages (from-to)193-203
Number of pages11
JournalBiophysical Journal
Volume72
Issue number1
StatePublished - Jan 1997
Externally publishedYes

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Hermissenda
Potassium
Neuronal Plasticity
4-Aminopyridine
Classical Conditioning
Patch-Clamp Techniques
Ammonium Compounds
Action Potentials
Cell Membrane
Neurons
Membranes

ASJC Scopus subject areas

  • Biophysics

Cite this

Potassium currents in presynaptic hair cells of Hermissenda. / Yamoah, Ebenezer N.

In: Biophysical Journal, Vol. 72, No. 1, 01.1997, p. 193-203.

Research output: Contribution to journalArticle

Yamoah, Ebenezer N. / Potassium currents in presynaptic hair cells of Hermissenda. In: Biophysical Journal. 1997 ; Vol. 72, No. 1. pp. 193-203.
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