Interaction between calcium-activated chloride channels and the cystic fibrosis transmembrane conductance regulator

We investigated interactions between cystic fibrosis conductance regulator (CFTR) and endogenous Ca2+-activated Cl- channels (CaCC) in bovine pulmonar y artery endothelium (CPAE). CPAE cells, which do not express CFTR, were tr ansiently transfected with wildtype (WT) CFTR and the deletion mutant Delta F508 CFTR. Currents through CaCC were significantly reduced after expressi on of WT CFTR. This inhibition was increased by stimulation (isobutylmethyl xanthine, forskolin) of CFTR in cells expressing WT CFTR. There were no suc h effects when Delta F508 mutant CFTR, which is retained in the endoplasmic reticulum, was expressed. It is concluded that CFTR and CaCC are functiona lly coupled probably through a direct channel-channel interaction.