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This Article Full Text Full Text (PDF) All Versions of this Article: 286/6/F1154    most recent 00453.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Li, C. Articles by Frøkiær, J. Search for Related Content PubMed PubMed Citation Articles by Li, C. Articles by Frøkiær, J.

Altered expression of urea transporters in response to ureteral obstruction

¹The Water and Salt Research Center, University of Aarhus, DK-8000 Aarhus C; ²Institute of Experimental Clinical Research and ⁶Department of Clinical Physiology, Aarhus University Hospital-Skejby, DK-8200 Aarhus N; ⁴Department of Cell Biology, Institute of Anatomy, University of Aarhus, DK-8000 Aarhus C, Denmark; ³Renal Division, Department of Medicine, Emory University, Atlanta, Georgia 30322; and ⁵Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892

Submitted 30 December 2003 ; accepted in final form 11 February 2004

Urea plays an important role in the urinary concentrating capacity. Renal inner medullary (IM) urea transporter expression was examined in rats with bilateral (BUO) or unilateral ureteral obstruction (UUO). BUO (24 h) was associated with markedly increased plasma urea (42.4 ± 1.0 vs. 5.2 ± 0.2 mmol/l) and a significant decease in expression of UT-A1 (28 ± 8% of sham levels), UT-A3 (45 ± 11%), and UT-B (70 ± 8%). Immunocytochemistry confirmed downregulation of UT-A1 and UT-A3 in IM collecting duct and UT-B in the descending vasa recta. Three days after release of BUO, UT-A1, UT-A3, and UT-B remained significantly downregulated (UT-A1: 37 ± 6%; UT-A3: 25 ± 6%; and UT-B: 10 ± 5% of sham levels; P < 0.05) concurrent with a persistent polyuria and a marked reduction in solute-free water reabsorption (115 ± 11 vs. 196 ± 8 µl·min^–1·kg^–1, P < 0.05). Moreover, 14 days after release of BUO, total UT-A1, UT-A3, and UT-B remained significantly decreased compared with sham-operated controls and urine urea remained reduced (588 ± 43 vs. 1,150 ± 94 mmol/l). Consistent with increased levels of plasma urea 24 h after onset of UUO (7.4 ± 0.3 vs. 4.8 ± 0.3 mmol/l), the protein abundance of UT-A1, UT-A3, and UT-B in IM was markedly reduced in the obstructed kidney, which was confirmed by immunocytochemistry. In the nonobstructed kidney, the expression of urea transporters did not change. In conclusion, reduced expression of UT-A1, UT-A3, and UT-B levels in both BUO and UUO rats suggests that urea transporters play important roles in the impaired urinary concentrating capacity in response to urinary tract obstruction.

collecting duct; descending vasa recta; obstructive nephropathy; urine concentrating mechanism

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