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Urea transporter expression in aging kidney and brain during dehydration
M-M Trinh-Trang-Tan1, G Geelen, L Teillet
1Institut National de la Santé et de la Recherche Médicale U76, Institut National de Transfusion Sanguine, 6, rue Alexandre Cabanel, F-75015 Paris, France. trinh@idf.inserm.fr
Summary
Aging impairs kidney function, reducing urine concentration ability in older rats due to lower urea transporter levels. Even when dehydrated, senescent rats struggle to concentrate urine effectively compared to younger ones.
Area of Science:
- Nephrology
- Gerontology
- Physiology
Background:
- Aging is linked to diminished urine-concentrating capacity.
- Kidney function, particularly urea transport, is crucial for concentrating urine.
Purpose of the Study:
- To investigate urea transporter (UT) regulation in the kidneys and brain of aged rats during dehydration.
- To compare the response of senescent rats to dehydration with that of adult rats.
Main Methods:
- Studied 30-month-old (senescent) and 10-month-old (adult) female WAG/Rij rats.
- Assessed kidney and brain responses to 2 days of water deprivation.
- Measured plasma vasopressin, urine osmolality, papillary urea concentration, and urea transporter (UT-A1, UT-A3, UT-B1, UT-A2) and aquaporin-4 abundances.
Main Results:
- Senescent rats had lower basal urine osmolality, papillary urea, and kidney UT abundances (UT-A1, UT-A3, UT-B1).
- Both groups increased plasma vasopressin upon dehydration, but senescent rats achieved lower papillary urea concentration.
- Dehydration led to decreased UT-A1 and UT-A3 in the inner medulla tip but increased UT-A1 in the base in senescent rats.
- Aging increased brain UT-B1 and aquaporin-4 abundances, unaffected by dehydration.
Conclusions:
- Reduced papillary urea concentration, linked to altered urea transporter regulation, underlies the impaired urine concentration in aging rats.
- Kidney urea transporter regulation is significantly altered in aged rats, contributing to functional decline.
- Brain aquaporin-4 and urea transporter levels increase with age, independent of hydration status.
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