The air-liquid interface cultures of Calu-3 cells were exposed to either 0 mM or 100 mM of ethanol at the basolateral side for 24 hours. On the apical surface the cells were stimulated with 100 mM of adenosine. The cells were washed with PBS containing 100 mM IBMX to inhibit phosphodiesterases that might degrade cAMP. The cells were lysed and cAMP was measured by cAMP immunoassay (R&D Systems, Minneapolis, MN). IBMX (100 mM) was also included in the lysis buffer. The samples were read at 450 nm using a spectrophotometer (BioTEK, Winooski, VT). All the treatments were carried out in quadruplicates.