Nucleotides within the airway surface liquid (ASL) regulate airway epithelial ion transport
rates by Ca 2+-and protein kinase C-dependent mechanisms via activation of specific P2Y
receptors. Extracellular adenine nucleotides also serve as precursors for adenosine, which
promotes cyclic AMP-mediated activation of the cystic fibrosis transmembrane regulator
chloride channel via A 2b adenosine receptors. A biological role for extracellular ATP in ASL
volume homeostasis has been suggested by the demonstration of regulated ATP release …