title: Urinary aquaporin 2 and calciuria correlate with the severity of enuresis in children.
abstract: This study examined the hypothesis that nocturnal enuresis might be paralleled by aquaporin 2 (AQP2) urinary excretion. Eighty children who experienced nocturnal enuresis were studied and compared with 9 healthy children. The 24-h urine samples were divided into two portions: night collections and day collections. Creatinine equivalents of urine samples from each patient were analyzed by Western blotting. AQP2 levels were semiquantified by densitometric scanning and reported as a ratio between the intensity of the signal in the day urine sample versus the night urine sample (D/N AQP2 ratio). The D/N AQP2 ratio was 0.59 +/- 0.11 (n = 9) in healthy children and increased to 1.27 +/- 0.24 (n = 10) in a subpopulation of enuretic children who had low nocturnal vasopressin levels. In enuretic children who displayed hypercalciuria and had normal vasopressin levels, the D/N AQP2 ratio was 1.05 +/- 0.27 (n = 8). These data indicate that reduced secretion of vasopressin and absorptive hypercalciuria are independently associated with an approximately twofold increase in the urinary D/N AQP2 ratio. When low nocturnal vasopressin levels were associated with hypercalciuria, a nearly threefold increase in the D/N AQP2 ratio was observed (1. 67 +/- 0.41, n = 11). In addition, in all enuretic patients tested, the urinary D/N AQP2 ratio correlates perfectly with the severity of the disorder (nocturnal polyuria). The findings reported in this article indicate that urinary AQP2 correlates with the severity of enuresis in children.
authors.affiliation: Department of General and Environmental Physiology, University of Bari, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Valenti
authors.affiliation: Department of General and Environmental Physiology, University of Bari, Italy.
authors.forename: Antonia
authors.initials: A
authors.lastname: Laera
authors.affiliation: Department of Emergency and Transplantation (DETO), University of Bari, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pace
authors.affiliation: Department of Developmental Age Biomedicine, University of Bari, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Aceto
authors.affiliation: Department of Developmental Age Biomedicine, University of Bari, Italy.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Lospalluti
authors.affiliation: Department of Developmental Age Biomedicine, University of Bari, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Penza
authors.affiliation: Department of Emergency and Transplantation (DETO), University of Bari, Italy.
authors.forename: Francesco P
authors.initials: FP
authors.lastname: Selvaggi
authors.affiliation: Department of Pediatrics, University of Padova, Italy.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Chiozza
authors.affiliation: Department of General and Environmental Physiology, University of Bari, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Svelto
mesh_terms: D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000652:urine*; D002118:Calcium / Q000652:urine*; D002648:Child; D002940:Circadian Rhythm; D004775:Enuresis / Q000503:physiopathology / Q000652:urine*; D006801:Humans; D015151:Immunoblotting; D012016:Reference Values
chemical_list: C496023:AQP2 protein, human; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D002118:Calcium