Vasopressin-stimulated CFTR Cl- currents are increased in the renal collecting duct cells of a mouse model of Liddle's syndrome.
Liddle's syndrome is a genetic form of hypertension linked to Na(+) retention caused by activating mutations in the COOH terminus of the beta or gamma subunit of the epithelial sodium channel (ENaC). In this study, we used the short-circuit current (I(sc)) method to investigate the effects of deamino-8-d-arginine vasopressin (dDAVP) on Na(+) and Cl(-) fluxes in primary cultures of cortical collecting ducts (CCDs) microdissected from the kidneys of mice with Liddle's syndrome carrying a stop codon mutation, corresponding to the beta-ENaC R(566) stop mutation (L) found in the original pedigree. Compared to wild-type (+/+) CCD cells, untreated L/+ and L/L CCD cells exhibited 2.7- and 4.2-fold increases, respectively, in amiloride-sensitive (Ams) I(sc), reflecting ENaC-dependent Na(+) absorption. Short-term incubation with dDAVP caused a rapid and significant increase (approximately 2-fold) in Ams I(sc) in +/+, but not in L/+ or L/L CCD cells. In sharp contrast, dDAVP induced a greater increase in 5-nitro-2-(3-phenylpropamino)benzoate (NPPB)-inhibited apical Cl(-) currents in amiloride-treated L/L and L/+ cells than in their +/+ counterparts. I(sc) recordings performed under apical ion substituted conditions revealed that the dDAVP-stimulated apical secretion of Cl(-), which was absent in cultured CCDs lacking CFTR, was 1.8-fold greater in L/+ and 3.7-fold greater in L/L CCD cells than in their +/+ CCD counterparts. After the basal membrane had been permeabilized with nystatin and a basal-to-apical Cl(-) gradient had been imposed, dDAVP also stimulated larger Cl(-) currents across L/L and L/+ CCD layers than +/+ CCD layers. These findings demonstrate that vasopressin stimulates greater apical CFTR Cl(-) conductance in the renal CCD cells of mice with Liddle's syndrome than in wild-type mice. This effect could contribute to the enhanced NaCl reabsorption observed in the distal nephron of patients with Liddle's syndrome.
Chang
Chiz-Tzung
CT
INSERM U478, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, BP 416, 75870 Paris Cedex 18, France.
Bens
Marcelle
M
Hummler
Edith
E
Boulkroun
Sheerazed
S
Schild
Laurent
L
Teulon
Jacques
J
Rossier
Bernard C
BC
Vandewalle
Alain
A
D000818:Animals; D002478:Cells, Cultured; D065101:Chloride Channel Agonists; D018118:Chloride Channels / Q000235:genetics; D002712:Chlorides / Q000378:metabolism; D003062:Codon / Q000235:genetics; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000502:physiology*; D003894:Deamino Arginine Vasopressin / Q000378:metabolism / Q000494:pharmacology; D004594:Electrophysiology; D053503:Epithelial Sodium Channels; D006973:Hypertension / Q000235:genetics* / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009399:Nephrons / Q000378:metabolism; D009761:Nystatin / Q000494:pharmacology; D009924:Organ Culture Techniques; D010641:Phenotype; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D013577:Syndrome; D014667:Vasopressins / Q000494:pharmacology*
D065101:Chloride Channel Agonists; D018118:Chloride Channels; D002712:Chlorides; D003062:Codon; D053503:Epithelial Sodium Channels; D012333:RNA, Messenger; D015222:Sodium Channels; D014667:Vasopressins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D009761:Nystatin; D012964:Sodium; D003894:Deamino Arginine Vasopressin