The adenosine-stimulated chloride transport is mediated through the CFTR channel CFTR has been found to be a major chloride channel in the airway epithelium responsible for adenosine-induced ion transport [30] #. To validate if CFTR is responsible for the observed adenosine-stimulated chloride transport in the Calu-3 epithelia, we applied CFTR channel inhibitor CFTR inh 172 to the apical side of Calu-3 epithelia for 30 minutes, followed by adenosine stimulation. The chloride conductance was decreased by ,76% when CFTR was inhibited (Fig. 3) , which is significantly lower than that of the no drug control (p,0.01, n = 5). To seek a second approach to confirm the result, CFBE41o cells, an airway epithelial cell line derived from a cystic fibrosis (CF) patient with homozygous DF508 mutations in CFTR, were used [24] . Strikingly, adenosine failed to elicit any chloride currents across the CF epithelia (p,0.01, N = 4). Thus, the currents under our experimental condition and drug profile are CFTR-mediated chloride conductance. These data altogether confirmed that in airway epithelial cells ethanolsuppression of chloride transport is mediated through CFTR, a cAMP-activated chloride channel.