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Postsynaptic Recordings at Afferent Dendrites Contacting Cochlear Inner Hair Cells: Monitoring Multivesicular Release at a Ribbon Synapse
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Postsynaptic Recordings at Afferent Dendrites Contacting Cochlear Inner Hair Cells: Monitoring Multivesicular Release at a Ribbon Synapse

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Voltage-dependent outward K(+) current in intermediate cell of stria vascularis of gerbil cochlea

S Takeuchi1, M Ando

  • 1Department of Physiology, Kochi Medical School, Nankoku 783-8505, Japan. takeuchi@kochi-ms.ac.jp

The American Journal of Physiology
|July 17, 1999
PubMed

Insights

Researchers studied voltage-dependent potassium (K(V)) currents in cochlear stria vascularis melanocytes. This K(V) current stabilizes membrane potential and aids potassium secretion, crucial for hearing.

Area of Science:

  • Otolaryngology
  • Cell Physiology
  • Molecular Biology

Background:

  • The stria vascularis in the cochlea maintains the endocochlear potential, essential for hearing.
  • Intermediate cells (melanocytes) play a role in cochlear function, but their ion transport mechanisms are not fully understood.

Purpose of the Study:

  • To characterize the voltage-dependent outward potassium (K(V)) current in cochlear stria vascularis intermediate cells.
  • To investigate the physiological role of this K(V) current in relation to membrane potential and potassium secretion.

Main Methods:

  • Whole-cell patch-clamp electrophysiology was used to record K(V) currents.
  • Pharmacological agents were employed to identify the properties and blockers of the current.
  • Kinetic analysis was performed to describe activation and inactivation properties.

Main Results:

  • A distinct K(V) current was identified with a threshold of -80 mV and 50% activation at -42.6 mV.
  • The current exhibited slow activation and incomplete inactivation, independent of intracellular calcium.
  • Quinine, verapamil, Ba(2+), and tetraethylammonium dose-dependently inhibited the current, while 4-aminopyridine was ineffective.

Conclusions:

  • The identified K(V) current likely stabilizes the intermediate cell membrane potential.
  • This conductance may contribute to potassium secretion into the intercellular space, influencing the endocochlear potential.
  • These findings offer insights into the electrophysiology of cochlear melanocytes and hearing.

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