Figure 1.

Differential regulation of airway surface liquid (ASL) pH in the pig large and small airway epithelium. The diagram shows proposed differential mechanisms regulating ASL pH in the large and small airways mediated by ATP12A and ATP6V0D2, respectively, balanced with CFTR (cystic fibrosis transmembrane conductance regulator). In CF pig small airways, defective anion transport into the airway lumen (i.e., Cl⁻ and HCO3⁻), mediated by CFTR, results in reduced ASL pH and impaired mucociliary transport. CF = cystic fibrosis; MCT = mucociliary transport; PCL = periciliary layer.