The cystic fibrosis transmembrane regulator (CFTR) in the kidney

The cystic fibrosis transmembrane regulator (CFTR) is a Cl- channel. Mutati ons of this transporter lead to a defect of chloride secretion by epithelia l culls causing the Cystic Fibrosis disease (CF). In spite of the high expr ession of CFTR in the kidney, patients with CF do not show major renal dysf unction, but it is known that both the urinary excretion of drugs and the r enal capacity to concentrate and dilute urine is deficient. CFTR mRNA is ex pressed in all nephron segments and its protein is involved with chloride s ecretion in the distal tubule, and the principal cells of the cortical (CCD ) and medullary (IMCD) collecting ducts. Several studios have demonstrated that CFTR does not only transport Cl- but also secretes ATP and, thus, cont rols other conductances such as Na+ (ENaC) and K+ (ROMK2) channels, especia lly in CCD. In the polycystic kidney the secretion of chloride through CFTR contributes to the cyst enlargement. This review is focused on the role of CFTR in the kidney and the implicatio ns of extracellular volume regulators, such as hormones, on its function an d expression.