Expression and function of the epithelial sodium channel [delta]-subunit in human respiratory epithelial cells in vitro

• Published in: Pflügers Archiv Vol. 467; no. 11; p. 2257
• Main Authors: Schwagerus, Elena, Sladek, Svenja, Buckley, Stephen T, Armas-capote, Natalia, de la Rosa, Diego Alvarez, Harvey, Brian J, Fischer, Horst, Illek, Beate, Huwer, Hanno, Schneider-daum, Nicole, Lehr, Claus-michael, Ehrhardt, Carsten
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.11.2015
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/s00424-015-1693-5

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 ^sub 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 ^sub 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.