Role of anion exchangers in Cl- and HCO3- secretion by the human airway epithelial cell line Calu-3

Dusik Kim, Juyeon Kim, B. Burghardt, Len Best, Martin C. Steward

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Despite the importance of airway surface liquid pH in the lung's defenses against infection, the mechanism of airway HCO3- secretion remains unclear. Our aim was to assess the contribution of apical and basolateral Cl-/HCO3- exchangers to Cl- and HCO3- transport in the Calu-3 cell line, derived from human airway submucosal glands. Changes in intracellular pH (pHi) were measured following substitution of Cl- with gluconate. Apical Cl- substitution led to an alkalinization in forskolin-stimulated cells, indicative of Cl-/HCO3- exchange. This was unaffected by the anion exchange inhibitor DIDS but inhibited by the CFTR blocker CFTRinh-172, suggesting that the HCO3- influx might occur via CFTR, rather than a solute carrier family 26 (SLC26) exchanger, as recently proposed. The anion selectivity of the recovery process more closely resembled that of CFTR than an SLC26 exchanger, and quantitative RT-PCR showed only low levels of SLC26 exchanger transcripts relative to CFTR and anion exchanger 2 (AE2). For pHi to rise to observed values (~7.8) through HCO3- entry via CFTR, the apical membrane potential must reverse to at least +20 mV following Cl- substitution; this was confirmed by perforated-patch recordings. Substitution of basolateral Cl- evoked a DIDS-sensitive alkalinization, attributed to Cl-/HCO3- exchange via AE2. This appeared to be abolished in forskolin-stimulated cells but was unmasked by blocking apical efflux of HCO3- via CFTR. We conclude that Calu-3 cells secrete HCO3- predominantly via CFTR, and, contrary to previous reports, the basolateral anion exchanger AE2 remains active during stimulation, providing an important pathway for basolateral Cl- uptake.

Original languageEnglish
JournalAmerican Journal of Physiology - Cell Physiology
Volume307
Issue number2
DOIs
Publication statusPublished - Jul 15 2014

Fingerprint

Chloride-Bicarbonate Antiporters
Anions
Epithelial Cells
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
Cell Line
Colforsin
Membrane Potentials
Polymerase Chain Reaction
Lung
Infection

Keywords

  • Airway surface liquid
  • Anion exchanger 2
  • Bicarbonate
  • Cystic fibrosis
  • Cystic fibrosis transmembrane conductance regulator
  • Intracellular pH
  • SLC26A4 (pendrin)

ASJC Scopus subject areas

  • Cell Biology
  • Physiology

Cite this

Role of anion exchangers in Cl- and HCO3- secretion by the human airway epithelial cell line Calu-3. / Kim, Dusik; Kim, Juyeon; Burghardt, B.; Best, Len; Steward, Martin C.

In: American Journal of Physiology - Cell Physiology, Vol. 307, No. 2, 15.07.2014.

Research output: Contribution to journalArticle

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