The purpose of this study was to characterize basolateral anion channels in Calu-3 and normal human bronchial epithelial (NHBE) cells, and their role in anion secretion. Patch clamp studies identified an outwardly rectifying Cl^- channel (ORCC), which could be activated by the adenosine receptor agonist - NECA. Short-circuit current measurements revealed that NECA activates a basolateral, but not an apical, anion conductance sensitive to DIDS, and to 9-anthracenecarboxylic acid, but not to DNDS. Apical membrane permeabilization studies confirmed the presence of basolateral anion channels, established their halide permeability sequence (Cl^-Br^->>I^-) and demonstrated their outwardly rectifying nature. Experiments using H-89, forskolin, and Ht31 demonstrated that adenosine receptor dependent activation of basolateral ORCC was cAMP- and potentially A-kinase Anchoring Protein-dependent. Neither BAPTA-AM treatment, nor basolateral Ca 2⁺ removal, had any effect on the activation of these channels. Anion replacement and ³⁶Cl^- flux studies show that Calu-3 cells primarily secrete HCO₃^- when stimulated with NECA, and that Cl^- secretion can be stimulated by blocking basolateral ORCC; while NHBE cells exclusively secrete Cl^- under all conditions studied. We propose a novel model of anion secretion in which ORCC recycles Cl^- across the basolateral membrane allowing preferential HCO₃^- secretion.