Development of urinary concentrating capacity: role of aquaporin-2
| Autor: | Anita Aperia, Gianni Celsi, Søren Nielsen, D. Marples, Roger Belusa, Ann-Christine Eklöf, Masato Yasui |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Aging
medicine.medical_specialty Vasopressin Transcription Genetic Physiology Urinary system Molecular Sequence Data Biology Aquaporins Renal Agents Betamethasone Polymerase Chain Reaction Ion Channels Kidney Concentrating Ability Rats Sprague-Dawley Internal medicine medicine Renal medulla Animals Weaning Deamino Arginine Vasopressin RNA Messenger Kidney Aquaporin 2 Water transport Base Sequence Blotting Northern Immunohistochemistry Aquaporin 6 Rats medicine.anatomical_structure Endocrinology Molecular Probes Urine osmolality |
| Zdroj: | American Journal of Physiology-Renal Physiology. 271:F461-F468 |
| ISSN: | 1522-1466 1931-857X |
| DOI: | 10.1152/ajprenal.1996.271.2.f461 |
| Popis: | The capacity to concentrate urine develops progressively during postnatal life in most mammalian species. Here we have examined whether low expression of the arginine vasopressin (AVP)-activated water channel aquaporin-2 (AQP-2) may be a limiting factor for the concentrating capacity in the infant rats. Urine osmolality in response to 24-h dehydration increased significantly from 10 to 40 days of age. The most rapid increase occurred during the weaning period, i.e., days 15-20. A similar developmental pattern was observed for AQP-2 mRNA levels in the renal medulla. AQP-2 protein levels also increased markedly from day 10 to 40. Immunohistochemistry revealed that AQP-2 was exclusively located in collecting duct principal cells both in infant and adult rats but that the signal was much weaker in infants. To further examine the relationship between urinary concentrating capacity and AQP-2 expression, we treated rats with a single injection of betamethasone, which is known to accelerate maturation in several organs. Twenty-four hours after treatment, there was an increase in urine osmolality, renal medullary AQP-2 mRNA, and AQP-2 protein levels in infant but not in adult rats. A single injection of a specific V2 agonist caused within 6 h significant increase of AQP-2 mRNA in both infant and adult. The expression of the mRNA of three other transporters involved in the concentrating process, medullary Na(+)-K(+)-ATPase alpha-subunit, Na-K-2Cl cotransporter, and epithelial chloride channel also increased during the weaning period and were upregulated by glucocorticoids. We conclude that there is a well-synchronized development of the many of the components that determine the concentrating capacity and that the low expression of AQP-2 is one of the limiting factors for low concentrating capacity in infants. |
| Databáze: | OpenAIRE |
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