title: UT-B-deficient mice develop renal dysfunction and structural damage.
abstract: BACKGROUND
  Urea transporter UT-B is the major urea transporter in erythrocytes and the descending vasa recta in the kidney. In this study, we investigated the effects of long-term UT-B deficiency on functional and structural defect in the kidney of 16-and 52-week-old UT-B-null mice.
  
  
  METHODS
  UT-B-knockout mice were generated by targeted gene disruption and lacked UT-B protein expression in all organs. The urinary concentrating ability of mice was studied in terms of daily urine output, urine osmolality, and urine and plasma chemistries. Changes in renal morphology were evaluated by hematoxylin and eosin staining.
  
  
  RESULTS
  The UT-B-null mice showed defective urine concentrating ability. The daily urine output in UT-B-null mice (2.5 ± 0.1 ml) was 60% higher and urine osmolality (985 ± 151 mosm) was significantly lower than that in wild-type mice (1463 ± 227 mosm). The 52-week-old UT-B-null mice exhibited polyuria after water deprivation, although urine osmolality was increased. At 52 weeks of age, over 31% of UT-B-null mice exhibited renal medullary atrophy because of severe polyuria and hydronephrosis.
  
  
  CONCLUSIONS
  Long-term UT-B deficiency causes severe renal dysfunction and structural damage. These results demonstrate the important role of UT-B in countercurrent exchange and urine concentration.
authors.affiliation: Prostate Diseases Prevention and Treatment Research Center, Department of Pathophysiology, Norman Bethune College of Medicine, Jilin University, Changchun, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Yan
authors.initials: Y
authors.lastname: Meng
authors.forename: Tianluo
authors.initials: T
authors.lastname: Lei
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Jing
authors.initials: J
authors.lastname: Su
authors.forename: Xuejian
authors.initials: X
authors.lastname: Zhao
authors.forename: Baoxue
authors.initials: B
authors.lastname: Yang
mesh_terms: D000818:Animals; D005260:Female; D007668:Kidney; D007671:Kidney Concentrating Ability; D007674:Kidney Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D026901:Membrane Transport Proteins / Q000172:deficiency* / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic
chemical_list: D026901:Membrane Transport Proteins; C452857:urea transporter B, mouse