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The pH-sensitive translocation of V-ATPase in the small airway of cystic fibrosis pigs
Journal article   Peer reviewed

The pH-sensitive translocation of V-ATPase in the small airway of cystic fibrosis pigs

Raul Villacreses, Ian M. Thornell, Xiaopeng Li, Steven E. Mather, Jimena Urbano, David A. Stoltz and Joseph Zabner
American journal of physiology. Lung cellular and molecular physiology, Vol.327(5), pp.L749-L755
11/01/2024
DOI: 10.1152/ajplung.00147.2024
PMCID: PMC11563583
PMID: 39254087

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Abstract

In contrast to pig large airways, the pH of airway surface liquid (ASL) in pig small airways is regulated by CFTR mediated HCO - 3 secretion and the vacuolar-type H + ATPase (V-ATPase) proton secretion. We hypothesized that in Cystic Fibrosis (CF), the ASL pH of small airways is acidic, and the V-ATPase is internalized. We quantified proton secretion during the addition of an alkaline test solutions by measuring changes in a pH dependent fluorescent dye generated by porcine small airway epithelia in the absence and presence of bafilomycin A1. The pH-dependent translocation of V-ATPase in ex vivo and in vivo preparations was measured using immunolocalization of V-ATPase. We found that bafilomycin sensitive proton secretion stopped when the ASL pH was less than 7.10. In non-CF pigs and mice, we found that V-ATPase was localized in the apical membrane, and internalized when the lungs were instilled with a pH 6.8 solution.Studies where we immediately fixed lungs from pigs revealed apical V-ATPase detection in non-CF piglets and less apical detection in CF piglets. Our data suggest that V-ATPase in small airways is internalized when the ASL pH is acidic. The decrease in apical localization of V-ATPase in CF pigs is consistent with an acidic ASL pH.
airway surface liquid cystic fibrosis pH small airways V-ATPase

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