Neurochemical Research

, Volume 33, Issue 8, pp 1435–1441

Extracellular pH Modulates the Voltage-dependent Ca2+ Current and Low Threshold K+ Current in Hair Cells

  • Angélica Almanza
  • Francisco Mercado
  • Rosario Vega
  • Enrique Soto
Original Paper

Abstract

Extracellular protons have been shown to modulate voltage-activated ionic channels. It has been proposed that synaptic modulation by exocytosed vesicular protons would be a characteristic feature of ribbon-type synapses. Type-I hair cells have a calyceal afferent junction with a diffusionally restricted synaptic cleft. These led us to study the action of extracellular pH changes on the voltage-activated Ca2+ and K+ currents evaluated using a whole-cell patch clamp in isolated cells. The amplitude of the Ca2+ and the K+ current were reduced by extracellular acidification, but without significant changes with extracellular alkalization. A shift in the voltage dependence to a more positive membrane potential was achieved at pH < 6.8. Our results shows that the presynaptic K+ and Ca2+ currents are modulated by protons, indicating that protons released along with an afferent neurotransmitter would participate as a feedback mechanism in type-I hair cells.

Keywords

Calcium channel Potassium channel ERG KCNQ Inner ear Vestibular endorgans Ribbon synapse Synaptic Afferent synapse Proton Neuromodulation Neurotransmitter release 

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Angélica Almanza
    • 1
  • Francisco Mercado
    • 1
  • Rosario Vega
    • 1
  • Enrique Soto
    • 1
  1. 1.Instituto de FisiologíaUniversidad Autónoma de Puebla (BUAP)PueblaMexico

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