Detection of Na(+) transporter proteins in urine.
Previous studies have established that the vasopressin-regulated water channel of the collecting duct, aquaporin-2, is excreted in the urine, providing a means for assessment of regulation and dysregulation of aquaporin-2 in humans. This article addresses the hypothesis that membrane transporters from upstream nephron segments are normally detectable in urine. The experiments employed rabbit polyclonal antibodies against the major Na transporters of the proximal tubule (the type 3 Na-H exchanger [NHE3]), the thick ascending limb of Henle's loop (the bumetanide-sensitive Na-K-2Cl cotransporter [NKCC2]), and the distal convoluted tubule (the thiazide-sensitive Na-Cl cotransporter [NCC]) in immunoblotting experiments. All three of these transporters were readily detectable as high molecular weight complexes present in lowdensity membrane fractions from urine of normal rats. Cross linking studies of NHE3, NKCC2, and NCC revealed that high molecular weight complexes are normally present in renal tissue. The molecular weights of the complexes in urine matched those of the cross-linked complexes in native kidney tissue. The presence in urine of integral membrane proteins representative of each nephron segment raises the possibility that limited or comprehensive proteomic analysis of urine samples may be useful in clinical settings.
McKEE
J Andrew
JA
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.
Kumar
Shailesh
S
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.
Ecelbarger
Carolyn A
CA
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.
Fernández-Llama
Patricia
P
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.
Terris
James
J
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.|Department of Physiology, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
Knepper
Mark A
MA
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.
D000818:Animals; D020346:Aquaporins / Q000737:chemistry / Q000652:urine; D002352:Carrier Proteins / Q000737:chemistry / Q000652:urine*; D015180:Electrophoresis, Gel, Two-Dimensional; D015151:Immunoblotting; D008297:Male; D008970:Molecular Weight; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000737:chemistry; D049992:Sodium Chloride Symporters; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000737:chemistry / Q000652:urine*; D028021:Sodium-Potassium-Chloride Symporters; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters
D020346:Aquaporins; D002352:Carrier Proteins; D011955:Receptors, Drug; C000613385:SLC9A3 protein, human; C578876:Slc12a3 protein, rat; C000613387:Slc9a3 protein, rat; D049992:Sodium Chloride Symporters; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D028021:Sodium-Potassium-Chloride Symporters; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters; C064415:thiazide receptor