Expression and function of the epithelial sodium channel δ-subunit in human respiratory epithelial cells in vitro

Pflugers Arch. 2015 Nov;467(11):2257-73. doi: 10.1007/s00424-015-1693-5. Epub 2015 Feb 13.

Abstract

Using human airway epithelial cell lines (i.e. NCI-H441 and Calu-3) as well as human alveolar epithelial type I-like (ATI) cells in primary culture, we studied the contribution of the epithelial sodium channel δ-subunit (δ-ENaC) to transepithelial sodium transport in human lung in vitro. Endogenous δ-ENaC protein was present in all three cell types tested; however, protein abundance was low, and no expression was detected in the apical cell membrane of these cells. Similarly, known modulators of δ-ENaC activity, such as capsazepine and icilin (activators) and Evans blue (inhibitor), did not show effects on short-circuit current (I SC), suggesting that δ-ENaC is not involved in the modulation of transcellular sodium absorption in NCI-H441 cell monolayers. Over-expression of δ-ENaC in NCI-H441 cells resulted in detectable protein expression in the apical cell membrane, as well as capsazepine and icilin-stimulated increases in I SC that were effectively blocked by Evans blue and that were consistent with δ-ENaC activation and inhibition, respectively. Consequently, these observations suggest that δ-ENaC expression is low in NCI-H441, Calu-3, and ATI cells and does not contribute to transepithelial sodium absorption.

Keywords: Airway epithelium; Alveolar epithelium; ENaC; Sodium absorption; Ussing chamber.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Capsaicin / analogs & derivatives
  • Capsaicin / pharmacology
  • Diuretics / pharmacology
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • Epithelial Sodium Channels / biosynthesis
  • Epithelial Sodium Channels / genetics
  • Epithelial Sodium Channels / metabolism*
  • Evans Blue / pharmacology
  • Gene Knockdown Techniques
  • Humans
  • Primary Cell Culture
  • Pulmonary Alveoli / cytology
  • Pulmonary Alveoli / drug effects
  • Pyrimidinones / pharmacology
  • Respiratory Mucosa / cytology
  • Respiratory Mucosa / drug effects
  • Respiratory Mucosa / metabolism*
  • Sodium / metabolism

Substances

  • Diuretics
  • Epithelial Sodium Channels
  • Pyrimidinones
  • SCNN1D protein, human
  • Evans Blue
  • Sodium
  • icilin
  • capsazepine
  • Capsaicin