[CFTR as cAMP-dependent chloride channels and as cAMP-dependent regulator of sodium channels]

Cystic fibrosis transmembrane conductance regulator (CFTR) is mutated in cystic fibrosis (CF) patients. It has been established that CFTR functions as a cAMP-dependent chloride channel. Therefore mutation of CFTR causes the abnormality of the chloride ion secretion. Furthermore, it has been shown recently that CFTR functions as cAMP-dependent negative regulator of sodium channels. The evidence accounts an abnormally high rate of sodium ion in the airway epithelia of the CF patients.