Amiloride‐sensitive fluid resorption in NCI‐H441 lung epithelia depends on an apical Cl− conductance

Physiological Reports

Jonas P. Korbmacher¹  Christiane Michel¹  Daniel Neubauer²  Kristin Thompson¹  Boris Mizaikoff²  Manfred Frick¹  Paul Dietl¹ 

[1] Institute of General Physiology, Ulm University, Ulm, Germany;Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany

关键词: Cl− channels;    epithelial transport;    fluid resorption;    lung;   

DOI  :  10.1002/phy2.201

来源: Wiley

【 摘 要 】

Abstract

Proper apical airway surface hydration is essential to maintain lung function. This hydration depends on well-balanced water resorption and secretion. The mechanisms involved in resorption are still a matter of debate, especially as the measurement of transepithelial water transport remains challenging. In this study, we combined classical short circuit current (I_SC) measurements with a novel D₂O dilution method to correlate ion and water transport in order to reveal basic transport mechanisms in lung epithelia. D₂O dilution method enabled precise analysis of water resorption with an unprecedented resolution. NCI-H441 cells cultured at an air–liquid interface resorbed water at a rate of 1.5 ± 0.4 μL/(h cm²). Water resorption and I_SC were reduced by almost 80% in the presence of the bulk Cl⁻ channel inhibitor 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) or amiloride, a specific inhibitor of epithelial sodium channel (ENaC). However, water resorption and I_SC were only moderately affected by forskolin or cystic fibrosis transmembrane regulator (CFTR) channel inhibitors (CFTR_inh-172 and glybenclamide). In line with previous studies, we demonstrate that water resorption depends on ENaC, and CFTR channels have only a minor but probably modulating effect on water resorption. However, the major ENaC-mediated water resorption depends on an apical non-CFTR Cl⁻ conductance.

【 授权许可】

CC BY   
© 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

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