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Vasopressin regulates aquaporin‐4 expression along the rat kidney connecting tubule and collecting duct
Author(s) -
Poulsen Søren Brandt,
Kim Young Hee,
Frøkiær Jørgen,
Nielsen Søren,
Christensen Birgitte Mønster
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.840.4
The final reabsorption of water takes place in the kidney connecting tubule (CNT) cells and collecting duct (CD) principal cells through the AQP2, ‐3 and ‐4 water channels. AQP2 and ‐3 are known to be regulated by vasopressin, whereas the regulation of AQP4 is less well described. This study examined the expression of AQP4 along the CNT and CD in vasopressin‐deficient Brattleboro (BB) rats and BB rats subjected to dDAVP for six days. The dDAVP administration induced a lower urine output and higher urine osmolality. Immunoblotting revealed increased AQP4 expression in cortex/outer stripe of outer medulla (OSOM), inner stripe of outer medulla (ISOM) and inner medulla (IM) in response to dDAVP. Immunohistochemistry confirmed the upregulation in the cortex/OSOM and ISOM. In the IM, however, dDAVP only increased AQP4 expression in the initial part of IMCD, whereas in the terminal part of IMCD AQP4 labeling was weak or absent although the untreated BB rats clearly expressed AQP4 in this segment. Immunoelectron microscopy of the initial part of the IMCD revealed AQP4 expression mainly in the basal plasma membrane in the untreated BB rats, whereas AQP4 was evenly expressed in the basal and lateral membrane in the dDAVP administrated BB rats. In conclusion, our results suggest that the expression of AQP4 along the CNT and CD is regulated by vasopressin. Financial support was provided by the Danish National Research Foundation.