Characterization of volume-sensitive taurine- and Cl--permeable channels

Luis J V Galietta, Simonetta Falzoni, Francesco D I Di Virgilio, Giovanni Romeo, Olga Zegarra-Moran

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Volume-sensitive Cl- channels [I(Cl(vol))] were studied using taurine efflux and patch-clamp experiments in 9HTEO- human tracheal cells. Cells were stimulated with the Ca2+-elevating agents ATP and ionomycin in isotonic medium or in hypotonic solutions. ATP (100 μM) or ionomycin (1 μM) and hypotonic shock produced a synergic effect. Indeed, the resulting taurine efflux was much higher than the sum of the single effects elicited by ATP, ionomycin, or hypotonic medium. The taurine release elicited by hypotonic shock and the potentiation by ATP and ionomycin were markedly inhibited by using a Ca2+-free extracellular medium and by incubating the cells with the membrane-permeable 1,2-bis(2-amino-phenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester chelating agent. Patch-clamp experiments confirmed the role of Ca2+ on I(Cl(vol)) channels. Swelling-induced taurine efflux was inhibited by reactive blue 2, suramin, and pyridoxal-phosphate-6-azophenyl- 2',4'-disulfonic acid. Patch-clamp experiments demonstrated that these compounds shift the voltage-dependent inactivation of I(Cl(vol)) channels toward more negative values. This study indicates that the sensitivity of I(Cl(vol)) to cell volume changes is modulated by intracellular Ca2+ and that purinergic receptor antagonists represent a new class of Cl- channel blockers.

Original languageEnglish
JournalAmerican Journal of Physiology - Cell Physiology
Issue number1 42-1
Publication statusPublished - Jul 1997


  • Cell volume regulation
  • Hypotonic shock
  • Ion channel blockers

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Physiology (medical)


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