title: The thiazide-sensitive Na-Cl cotransporter is an aldosterone-induced protein.
abstract: Although the collecting duct is regarded as the primary site at which mineralocorticoids regulate renal sodium transport in the kidney, recent evidence points to the distal convoluted tubule as a possible site of mineralocorticoid action. To investigate whether mineralocorticoids regulate the expression of the thiazide-sensitive Na-Cl cotransporter (TSC), the chief apical sodium entry pathway of distal convoluted tubule cells, we prepared an affinity-purified, peptide-directed antibody to TSC. On immunoblots, the antibody recognized a prominent 165-kDa band in membrane fractions from the renal cortex but not from the renal medulla. Immunofluorescence immunocytochemistry showed TSC labeling only in distal convoluted tubule cells. Semiquantitative immunoblotting studies demonstrated a large increase in TSC expression in the renal cortex of rats on a low-NaCl diet (207 +/- 21% of control diet). Immunofluorescence localization in tissue sections confirmed the strong increase in TSC expression. Treatment of rats for 10 days with a continuous subcutaneous infusion of aldosterone also increased TSC expression (380 +/- 58% of controls). Furthermore, 7-day treatment of rats with an orally administered mineralocorticoid, fludrocortisone, increased TSC expression (656 +/- 114% of controls). We conclude that the distal convoluted tubule is an important site of action of the mineralocorticoid aldosterone, which strongly up-regulates the expression of TSC.
authors.affiliation: Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: G H
authors.initials: GH
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Masilamani
authors.forename: R
authors.initials: R
authors.lastname: Turner
authors.forename: C
authors.initials: C
authors.lastname: Mitchell
authors.forename: J B
authors.initials: JB
authors.lastname: Wade
authors.forename: M A
authors.initials: MA
authors.lastname: Knepper
mesh_terms: D000450:Aldosterone / Q000008:administration & dosage / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001581:Benzothiadiazines; D002352:Carrier Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D004039:Diet, Sodium-Restricted; D004232:Diuretics; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D015151:Immunoblotting; D007262:Infusions, Intravenous; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D049993:Sodium Chloride Symporter Inhibitors / Q000494:pharmacology*; D049992:Sodium Chloride Symporters; D027981:Symporters
chemical_list: D000906:Antibodies; D001581:Benzothiadiazines; D002352:Carrier Proteins; D004232:Diuretics; D010446:Peptide Fragments; D049993:Sodium Chloride Symporter Inhibitors; D049992:Sodium Chloride Symporters; D027981:Symporters; D000450:Aldosterone