Modulation by extracellular and intracellular iodide of volume-activated Cl- current in HeLa cells.
The patch-clamp technique was used to study the effect of extracellular and intracellular iodide on the properties of the volume-activated anion current in HeLa cells. Upon hypotonic challenge, HeLa cells responded by activating an outwardly rectifying Cl- current. Replacement of extracellular Cl- by I-, a more permeable anion, increased the peak outward and inward current, reduced the magnitude of deactivation observed at depolarized potentials and shifted the half-maximal (V0.5) deactivation voltage towards more positive values. On the other hand, when internal Cl- was replaced by I- the volume-activated current was not observed in normal, Cl--rich hypotonic extracellular solution. However, switching to a hypotonic extracellular solution containing a mixture of Cl- and I- resulted in the activation of the volume-sensitive current. Furthermore, once the current was activated, I- could be excluded from the external solution without significantly affecting the current properties. These results suggest that the permeant anion plays a crucial role in the gating mechanism of the volume-activated Cl- current, influencing the swelling-dependent activation and the voltage-dependent deactivation processes.
Stutzin
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A
Instituto de Ciencias Biomédicas, Facultad de Medicina Universidad de Chile, Casilla 70058, Santiago, Chile.
Eguiguren
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AL
Montes
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Sepúlveda
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FV
D000838:Anions; D048429:Cell Size; D018118:Chloride Channels / Q000502:physiology*; D002712:Chlorides / Q000494:pharmacology; D004553:Electric Conductivity; D005110:Extracellular Space; D006367:HeLa Cells / Q000502:physiology*; D006801:Humans; D007038:Hypotonic Solutions; D007424:Intracellular Fluid; D007454:Iodides / Q000494:pharmacology*; D015640:Ion Channel Gating; D018408:Patch-Clamp Techniques
D000838:Anions; D018118:Chloride Channels; D002712:Chlorides; D007038:Hypotonic Solutions; D007454:Iodides