Adenosine-evoked Na+ transport in human airway epithelial cells

Background and purpose: Absorptive epithelia express apical receptors that allow nucleotides to inhibit Na+ transport but ATP unexpectedly stimulated this process in an absorptive cell line derived from human bronchiolar epithelium (H441 cells) whilst UTP consistently caused inhibition. We have therefore examined the pharmacological basis of this anomalous effect of ATP.