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- Title
Decreased expression of aquaporin 2 in the collecting duct of mice lacking the vasopressin V1a receptor.
- Authors
Yasuoka, Yukiko; Kobayashi, Mizuka; Sato, Yuichi; Nonoguchi, Hiroshi; Tanoue, Akito; Okamoto, Hirotsugu; Kawahara, Katsumasa
- Abstract
Background: Vasopressin V1a receptor null (V1aR) mice recently showed incomplete urinary concentration due to higher urine volume during control and water diuresis (euhydration), but showed normal response during dehydration (Aoyagi et al., Am J Physiol 295: F100-7, ). Methods: Water balance, plasma vasopressin, plasma and urine osmolality, and aquaporin 2 (AQP2) expression in the kidney of wild-type (WT) and V1aR mice were therefore further examined using improved methods of urine collection (urinary bladder urine). Results: V1aR mice demonstrated a lower urine osmolality (3,360 ± 138 vs. 3,610 ± 47 mOsm/kgHO) and a higher plasma osmolality (354.3 ± 1.3 vs. 342.5 ± 1.5 mOsm/kgHO) after dehydration for 24 h compared to WT mice ( P < 0.05). In contrast, the plasma vasopressin concentration was significantly ( P < 0.001) higher in the V1aR mice (48.8 ± 4.8 vs. 22.1 ± 2.4 pg/ml). On the other hand, although the AQP2 protein expression in the kidney was increased after dehydration, the basal (control) and dehydration-induced AQP2 protein levels were significantly lower in V1aR mice compared to WT mice (by Western blotting). Staining by an anti-AQP2 antibody in the luminal membrane of the collecting ducts was increased in both V1aR and WT mice after dehydration, but was relatively weaker in the V1aR mice (by immunohistochemistry). Moreover, urinary excretion of AQP2 protein, an index of the luminal AQP2 expression, was significantly ( P < 0.05) lower in the V1aR mice. Conclusion: V1aR signaling may be fundamentally important for the expression of AQP2 in the collecting ducts during control conditions and dehydration.
- Subjects
AQUAPORIN genetics; GENE expression; LABORATORY mice; VASOPRESSIN; G protein coupled receptors; DIURESIS; DEHYDRATION
- Publication
Clinical & Experimental Nephrology, 2013, Vol 17, Issue 2, p183
- ISSN
1342-1751
- Publication type
Article
- DOI
10.1007/s10157-012-0686-3