title: Urinary aquaporin-2 levels in healthy volunteers.
abstract: Renal water handling is regulated by the release of arginine vasopressin (AVP) and the subsequent insertion of aquaporin 2 (AQP2) in the apical membrane of collecting duct cells. This in turn increases the membrane permeability to water and the passive reabsorption of water down the concentration gradient present in the medulla. Aquaporin 2 can be detected in the urine under conditions of antidiuresis. We wish to validate an assay for urinary AQP2. Fourteen volunteers participated in studies of water loading and water deprivation followed by the administration of 1-deamino-8-D-arginine vasopressin (dDAVP). Urine osmolality was measured by vapour pressure osmometry. Urinary AQP2 was measured by using a chemiluminescent assay. Baseline correlations between serum AVP levels, urinary osmolality and urinary AQP2 levels were not significant. Following the administration of dDAVP, a positive correlation between urine osmolality and urinary AQP2 was evident (r = 0.762). For specific conditions where renal water retention is stimulated via AVP, urinary AQP2 measurements provide a reproducible measurement of the renal actions of AVP.
authors.affiliation: Departments of Medicine and Physiology University of Otago, Dunedin, New Zealand.
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Dameh
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Bedford
authors.forename: John P
authors.initials: JP
authors.lastname: Leader
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Walker
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D051399:Aquaporin 2 / Q000652:urine*; D001127:Arginine Vasopressin / Q000097:blood; D003894:Deamino Arginine Vasopressin / Q000008:administration & dosage / Q000494:pharmacology*; D004326:Drinking; D005260:Female; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D007671:Kidney Concentrating Ability / Q000187:drug effects; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors; D016482:Urinalysis / Q000379:methods*; D014868:Water Deprivation
chemical_list: C496023:AQP2 protein, human; D051399:Aquaporin 2; D001127:Arginine Vasopressin; D003894:Deamino Arginine Vasopressin