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, 2008). 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/kgH2O) and a higher plasma osmolality (354.3 ± 1.3 vs. 342.5 ± 1.5 mOsm/kgH2O) 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.
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, 2008). 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/kgH2O) and a higher plasma osmolality (354.3 ± 1.3 vs. 342.5 ± 1.5 mOsm/kgH2O) 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.
Authors: H Nonoguchi; M Takayama; A Owada; K Ujiie; T Yamada; O Nakashima; Y Sakuma; J Koike; Y Terada; F Marumo; K Tomita Journal: Am J Med Sci Date: 1996-11 Impact factor: 2.378
Authors: K Kanno; S Sasaki; Y Hirata; S Ishikawa; K Fushimi; S Nakanishi; D G Bichet; F Marumo Journal: N Engl J Med Date: 1995-06-08 Impact factor: 91.245
Authors: Melissa A Wasilewski; Valerie D Myers; Fabio A Recchia; Arthur M Feldman; Douglas G Tilley Journal: Cell Signal Date: 2015-07-30 Impact factor: 4.315