A large-conductance voltage-dependent potassium channel in cultured pig articular chondrocytes

Jerzy W. Mozrzymas, Marco Martina, Fabio Ruzzier*

*Corresponding author for this work

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

The patch-clamp techniques were used to study voltage-dependent potassium channels in cultured pig articular chondrocytes. A predominant single-channel conductance of 125 pS was found. These channels were reversibly blocked by tetraethylammonium. In cell-attached patches, transient increases in the channel activity were observed, and defined as a switching between low and high activity modes CLAM and HAM). Open-time distributions could be described with two kinetics components (in LAM and HAM) having similar time constants (fast τ1 and slow τ2). In HAM, the area of the slow component was larger The mean burst length was significantly longer in HAM than in LAM. In both modes, the burst-length distributions were fitted with a sum of three exponentials. In LAM and HAM, the time constants τ1 and τ2 were indistinguishable from those of the open-time distributions. The slowest time constant, τ3, was strongly voltage dependent, and was significantly longer in HAM than in LAM. In both LAM and HAM, the ensemble currents were characterised by a rapid rising phase followed by fast and profound inactivation. The activation kinetics were similar, but the inactivation was faster in HAM. In the outside-out configuration no evidence for mode switching was found. The kinetics of the rising phase of the ensemble currents were also similar to those observed using the cell-attached configuration, but the channels did not inactivate. In the whole-cell configuration, the mode switching was not present. The inactivation time constant showed a large scattering, and was much slower than that measured in the cell-attached patch mode. These currents were blocked by tetraethylammonium and 4-aminopyridine. Our results indicate that intracellular factors are involved in controlling the mode switching and the kinetics of the inactivation of potassium channels in pig articular chondrocytes.

Original languageEnglish (US)
Pages (from-to)413-427
Number of pages15
JournalPflugers Archiv European Journal of Physiology
Volume433
Issue number4
DOIs
StatePublished - Feb 20 1997

    Fingerprint

Keywords

  • Chondrocytes
  • Inactivation
  • Mode switching
  • Patch clamp
  • Potassium channel

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

Cite this