Evidence that Ca2(+)-dependent activation of airway epithelia Cl- channels is not dependent on phosphorylation

Am J Physiol. 1990 Dec;259(6 Pt 1):L410-4. doi: 10.1152/ajplung.1990.259.6.L410.

Abstract

Previous studies have shown that an increase in the cytosolic Ca2+ concentration [( Ca2+]c) activates Cl- channels in airway epithelia but that the effect is indirect. Because adenosine 3',5'-cyclic monophosphate (cAMP) and phorbol myristate acetate (PMA) activate Cl- channels via phosphorylation by cAMP-dependent protein kinase and protein kinase C, respectively, we asked whether Ca2(+)-dependent Cl- channel activation is phosphorylation dependent. We measured 125I- efflux as an assay of Cl- channel activation in the intact cell. We found that depletion of cellular ATP prevented cAMP- and PMA-induced activation but did not alter activation produced by the Ca2+ ionophore A23187. Moreover, addition of high concentrations of staurosporine (5 microM), to nonspecifically inhibit kinase activity, blocked cAMP- and PMA-stimulated 125I- efflux but had no effect on A23187-induced efflux. These results suggest that elevation of [Ca2+]c does not activate Cl- channels via phosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Alkaloids / pharmacology
  • Animals
  • Calcimycin / pharmacology
  • Calcium / physiology*
  • Cells, Cultured
  • Chloride Channels
  • Cyclic AMP / metabolism
  • Cytosol / physiology
  • Dogs
  • Epithelium / physiology
  • Iodides / metabolism
  • Ion Channels / drug effects
  • Ion Channels / physiology*
  • Kinetics
  • Membrane Proteins / physiology*
  • Muscle, Smooth / physiology
  • Phosphorylation
  • Protein Kinase C / antagonists & inhibitors
  • Staurosporine
  • Tetradecanoylphorbol Acetate / pharmacology
  • Trachea / physiology*

Substances

  • Alkaloids
  • Chloride Channels
  • Iodides
  • Ion Channels
  • Membrane Proteins
  • Calcimycin
  • Adenosine Triphosphate
  • Cyclic AMP
  • Protein Kinase C
  • Staurosporine
  • Tetradecanoylphorbol Acetate
  • Calcium