Vasopressin-stimulated chloride transport in transimmortalized mouse cell lines derived from the distal convoluted tubule and cortical and inner medullary collecting ducts

Background. The fine control of NaCl absorption takes place in the distal p arts of the renal tubule, but the regulation of Cl- transport in this regio n has not been fully elucidated. We have analysed the effects of dD-arginin e vasopressin (dDAVP) on Cl- fluxes in cultured mouse distal convoluted tub ule (mpkDCT), cortical collecting duct (mpkCCD) and inner medullary collect ing duct (mpkIMCD) cell lines. Methods. RT-PCR and Western blotting were used to detect the amiloride-sens itive sodium channel (ENaC) and cystic fibrosis transmembrane conductance r egulator (CFTR) mRNAs and protein in cultured mpkDCT, mpkCCD and mpkIMCD ce lls. Cl- fluxes were analysed by measuring the short-circuit current (I-sc) and bidirectional Cl-36(-) fluxes on confluent cells grown on filters. Results. All three cell lines expressed ENaC and CFTR and had I-sc stimulat ed by dDAVP. The rise in I-sc caused by dDAVP (10(-8) M) was inhibited by a miloride, and to a lesser extent by 5-nitro2-(3-phenylpropylamino)-benzoic acid (NPPB) in all three cell lines. The dDAVP-dependent I-sc measured unde r apical Na+-free condition was reduced by Cl- channel blockers with a prof ile (NPPB > glibenclamide > DIDS), similar to that for rat CFTR. dDAVP stim ulated the apical-to-basal Cl-36(-) flux and to a lesser extent the basal-t o-apical Cl-36(-) flux under open-circuit condition in all three cultured c ell lines. Adding NPPB to the apical side reduced the basal-to-apical Cl-36 (-) flux but not the opposite Cl-36(-) flux from dDAVP-treated cells. Conclusion. These results indicate that dDAVP stimulates the bi-directional flux of Cl-, resulting in net Cl- absorption, in these cultured mouse dist al and collecting duct cells. I-sc experiments also suggest the presence of a minor component of electrogenic Cl- secretion, possibly mediated by CFTR .