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

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

J. P Clancy, J. D McCann and M. J Welsh
American journal of physiology. Lung cellular and molecular physiology, Vol.259(6), pp.L410-L414
12/01/1990
DOI: 10.1152/ajplung.1990.259.6.L410
PMID: 1701978

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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.

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