A volume-sensitive chloride conductance revealed in cultured human keratinocytes by 36Cl- efflux and whole-cell patch clamp recording

Michela Rugolo, Teresa Mastrocola, Michele De Luca, Giovanni Romeo, Luis J V Galietta

Research output: Contribution to journalArticlepeer-review

Abstract

The Cl- transport mechanism responsible for the stimulation of 36Cl- efflux after exposure to hypotonic medium (210 mosmol/kg) was investigated in human keratinocytes. The involvement of the anion exchanger and of the Cl-/cation cotransporters was ruled out by the finding that replacement of extracellular Cl- by the poorly permeant anion gluconate, and the addition of bumetanide and furosemide, inhibitors of Na+/K+/Cl- and K+/Cl- cotransporters, respectively, failed to significantly reduce the activation of Cl- efflux by hypotonic medium. 'Whole cell' configuration of the patch clamp technique directly revealed the presence of a macroscopic Cl- current, which was evoked by incubation with hypotonic medium and was reversed by elevation of the extracellular osmolality. Volume-sensitive current showed outward rectification of the current-voltage relationship and time-dependent inactivation at depolarizing voltages. This current was Cl- selective, because the zero-current reversal potential approached the Cl- equilibrium potential, when extracellular Cl- was replaced by gluconate. 0.1 mM, 1,9-dideoxyforskolin significantly reduced either 36Cl- efflux and the Cl- current, suggesting that the Cl- efflux and the macroscopic current activated after exposure to hypotonic medium are mediated by the same pathway. Electronic cell sizing showed that in keratinocytes hypotonic swelling was not followed by a significant regulatory volume decrease response.

Original languageEnglish
Pages (from-to)39-44
Number of pages6
JournalBBA - Biomembranes
Volume1112
Issue number1
DOIs
Publication statusPublished - Nov 23 1992

Keywords

  • (Human keratinocyte)
  • Chloride (Cl) efflux
  • Chloride current
  • Osmotic cell swelling
  • Patch clamp
  • Volume regulation
  • Whole-cell patch clamp

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology

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