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 parts of the renal tubule, but the regulation of Cl(-) transport in this region has not been fully elucidated. We have analysed the effects of dD-arginine vasopressin (dDAVP) on Cl(-) fluxes in cultured mouse distal convoluted tubule (mpkDCT), cortical collecting duct (mpkCCD) and inner medullary collecting duct (mpkIMCD) cell lines.


METHODS
RT-PCR and Western blotting were used to detect the amiloride-sensitive sodium channel (ENaC) and cystic fibrosis transmembrane conductance regulator (CFTR) mRNAs and protein in cultured mpkDCT, mpkCCD and mpkIMCD cells. Cl(-) fluxes were analysed by measuring the short-circuit current (I(sc)) and bidirectional (36)Cl(-) fluxes on confluent cells grown on filters.


RESULTS
All three cell lines expressed ENaC and CFTR and had I(sc) stimulated by dDAVP. The rise in I(sc) caused by dDAVP (10(-8) M) was inhibited by amiloride, and to a lesser extent by 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) in all three cell lines. The dDAVP-dependent I(sc) measured under apical Na(+)-free condition was reduced by Cl(-) channel blockers with a profile (NPPB>glibenclamide>DIDS), similar to that for rat CFTR. dDAVP stimulated the apical-to-basal (36)Cl(-) flux and to a lesser extent the basal-to-apical (36)Cl(-) flux under open-circuit condition in all three cultured cell lines. Adding NPPB to the apical side reduced the basal-to-apical (36)Cl(-) flux but not the opposite (36)Cl(-) flux from dDAVP-treated cells.


CONCLUSIONS
These results indicate that dDAVP stimulates the bi-directional flux of Cl(-), resulting in net Cl(-)absorption, in these cultured mouse distal and collecting duct cells. I(sc) experiments also suggest the presence of a minor component of electrogenic Cl(-) secretion, possibly mediated by CFTR.
Duong Van Huyen
J P
JP
Institut National de la Santé et de la Recherche Médicale, Unité 478, Institut Fédératif de Recherche 02, Faculté de Médecine Xavier Bichat, Paris, France.
Bens
M
M
Teulon
J
J
Vandewalle
A
A
D000818:Animals; D027321:Anion Transport Proteins; D001127:Arginine Vasopressin / Q000502:physiology*; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000502:physiology; D002461:Cell Line, Transformed; D002712:Chlorides / Q000493:pharmacokinetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology; D004594:Electrophysiology; D053503:Epithelial Sodium Channels; D007672:Kidney Cortex; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D007686:Kidney Tubules, Distal / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D012333:RNA, Messenger / Q000378:metabolism; D012076:Renal Agents / Q000494:pharmacology; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism
D027321:Anion Transport Proteins; D002352:Carrier Proteins; D002712:Chlorides; D053503:Epithelial Sodium Channels; D012333:RNA, Messenger; D012076:Renal Agents; D015222:Sodium Channels; D001127:Arginine Vasopressin; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D003894:Deamino Arginine Vasopressin