Abstract
We studied the role of CFTR in the Na(+)-K(+)-pump activity of Calu-3 human airway cells. To estimate the Na(+)-K(+)-pump activity on the basolateral membrane, the ouabain-sensitive component of the short-circuit current (Isc) was measured after permeabilization of the apical membrane with nystatin, a Na(+) ionophore. The Na(+)-K(+)-pump activity was diminished by a selective CFTR blocker (glybenclamide) or nonspecific Cl(-) channel inhibitors (NPPB and DPC) but not by outwardly rectifying Cl(-) channel blockers (DNDS, DIDS). Augmentation of anion conductance by 8-bromo-cyclic AMP (8Br-cAMP, 1 mM) potentiated the Na(+)-K(+)-pump activity that was reduced by blocking CFTR or by the replacement of Cl(-) with gluconate, a less membrane-permeant anion. The Na(+)-K(+)-pump activity was unaffected by the replacement of Cl(-) with NO(-)(3) that has equal permeability through the CFTR. These results suggest that the anion movement through the CFTR may contribute to the Na(+)-K(+)-pump activity in Calu-3 cells by regulating the rate of Na(+) entry.
Copyright 2000 Academic Press.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / pharmacology
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8-Bromo Cyclic Adenosine Monophosphate / pharmacology
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Anions / metabolism*
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Bronchi / cytology*
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Calcium Channel Blockers / pharmacology
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Cell Line
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Cystic Fibrosis Transmembrane Conductance Regulator / metabolism*
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Electrophysiology
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Glyburide / pharmacology
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Humans
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Ionophores / pharmacology
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Nitrobenzoates / pharmacology
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Nystatin / pharmacology
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Ouabain / pharmacology
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Sodium / metabolism
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Sodium-Potassium-Exchanging ATPase / drug effects
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Sodium-Potassium-Exchanging ATPase / metabolism*
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Stilbenes / pharmacology
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Time Factors
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ortho-Aminobenzoates / pharmacology
Substances
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Anions
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CFTR protein, human
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Calcium Channel Blockers
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Ionophores
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Nitrobenzoates
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Stilbenes
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ortho-Aminobenzoates
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Cystic Fibrosis Transmembrane Conductance Regulator
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Nystatin
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8-Bromo Cyclic Adenosine Monophosphate
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5-nitro-2-(3-phenylpropylamino)benzoic acid
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Ouabain
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4,4'-dinitro-2,2'-stilbenedisulfonic acid
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fenamic acid
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Sodium
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Sodium-Potassium-Exchanging ATPase
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4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
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Glyburide