CFTR disruption impairs cAMP-dependent Cl- secretion in primary cultures of mouse cortical collecting ducts

The role of the cystic fibrosis transmembrane conductance regulator (CFTR) in the renal cortical collecting duct (CCD) has not yet been fully elucidated. Here, we investigated the effects of deamino-8-D-arginine vasopressin (dDAVP) and isoproterenol (ISO) on NaCl transport in primary cultured CCDs microdissected from normal [CFTR(+/+)] and CFTR-knockout [CFTR(-/-)] mice. dDAVP stimulated the benzamyl amiloride (BAm)-sensitive transport of Na+ assessed by the short-circuit current (I-sc) method in both CFTR(+/+) and CFTR(-/-) CCDs to a very similar degree. Apical addition of 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) or glibenclamide partially inhibited the rise in I-sc induced by dDAVP and ISO in BAm-treated CFTR(+/+) CCDs, whereas dDAVP, ISO, and NPPB did not alter I-sc in BAm-treated CFTR(-/-) CCDs. dDAVP stimulated the apical-to-basal flux and, to a lesser extent, the basal-to-apical flux Of Cl-36(-) in CFTR(+/+) CCDs. dDAVP also increased the apical-to-basal Cl-36(-) flux in CFTR(-/-) CCDs but not the basal-to-apical Cl-36(-) flux. These results demonstrate that CFTR mediates the cAMP-stimulated component of secreted Cl- in mouse CCD.