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Am J Physiol Renal Physiol. 2013 Sep 15;305(6):F839-44. doi: 10.1152/ajprenal.00616.2012. Epub 2013 Jul 17.

Renalase regulates renal dopamine and phosphate metabolism.

Author information

1
Section of Nephrology, Dept. of Medicine, Yale School of Medicine, P.O. Box 208029, New Haven, CT 06520-8029. gary.desir@yale.edu.

Abstract

Renalase is a kidney-secreted catecholamines-degrading enzyme whose expression and activity are downregulated by increased dietary phosphate. A renalase knockout (KO) mouse model was used to explore the mechanisms mediating renalase's effect on phosphate excretion. Compared with wild-type (WT) mice maintained on a regular diet, KO mice show decreased serum PO4(-) (KO = 5.3 ± 0.2 vs. WT = 6.0 ± 0.1, n = 6; P < 0.04) and increased urinary PO4(-) excretion (urine PO4(-)/creatinine: KO = 7.7 ± 0.3 vs. WT = 6.1 ± 0.3, n = 6; P < 0.02). However, both WT and KO mice respond similarly to PO4(-) restriction by increasing renal COMT-1 activity and markedly decreasing PO4(-) excretion, which excludes an intrinsic renal defect in the KO. Renal sodium-phosphate cotransporter Npt2a, sodium proton exchanger NHE3 expression, and MAO-A and B activity did not differ between WT and KO. Only catechol-O-methyl transferase (COMT) expression and activity were significantly increased in KO mice. Despite that, urinary dopamine increased by twofold, whereas urinary l-DOPA excretion decreased by twofold in the KO mouse, indicating an upregulation of renal dopamine (DA) synthesis. These data indicate that renalase deficiency is associated with increased renal DA synthesis, stimulated PO4(-) excretion, and moderately severe hypophosphatemia. The signal to increase renal DA synthesis is strong since it overcomes a compensatory increase in COMT activity.

KEYWORDS:

dopamine; phosphate regulation; renalase

PMID:
23863468
PMCID:
PMC3761288
DOI:
10.1152/ajprenal.00616.2012
[Indexed for MEDLINE]
Free PMC Article

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