title: Comparison of cardiovascular aquaporin-1 changes during water restriction between 25- and 50-day-old rats.
abstract: OBJECTIVE
  Aquaporin-1 (AQP1) is the predominant water channel in the heart, linked to cardiovascular homeostasis. Our aim was to study cardiovascular AQP1 distribution and protein levels during osmotic stress and subsequent hydration during postnatal growth.
  
  
  METHODS
  Rats aged 25 and 50 days were divided in: 3d-WR: water restriction 3 days; 3d-WAL: water ad libitum 3 days; 6d-WR+ORS: water restriction 3 days + oral rehydration solution (ORS) 3 days; and 6d-WAL: water ad libitum 6 days. AQP1 was evaluated by immunohistochemistry and western blot in left ventricle, right atrium and thoracic aorta.
  
  
  RESULTS
  Water restriction induced a hypohydration state in both age groups (40 and 25 % loss of body weight in 25- and 50-day-old rats, respectively), reversible with ORS therapy. Cardiac AQP1 was localized in the endocardium and endothelium in both age groups, being evident in cardiomyocytes membrane only in 50-day-old 3d-WR group, which presented increased protein levels of AQP1; no changes were observed in the ventricle of pups. In vascular tissue, AQP1 was present in the smooth muscle of pups; in the oldest group, it was found in the endothelium, increasing after rehydration in smooth muscle. No differences were observed between control groups 3d-WAL and 6d-WAL of both ages.
  
  
  CONCLUSIONS
  Our findings suggest that cardiovascular AQP1 can be differentially regulated in response to hydration status in vivo, being this response dependent on postnatal growth. The lack of adaptive mechanisms of mature animals in young pups may indicate an important role of this water channel in maintaining fluid balance during hypovolemic state.
authors.affiliation: Cátedra de Fisiología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, IQUIMEFA, CONICET, Junín 956, C1113AAD, Buenos Aires, Argentina, vnetti@conicet.gov.ar.
authors.forename: Vanina A
authors.initials: VA
authors.lastname: Netti
authors.forename: Mariana C
authors.initials: MC
authors.lastname: Vatrella
authors.forename: Melina F
authors.initials: MF
authors.lastname: Chamorro
authors.forename: María I
authors.initials: MI
authors.lastname: Rosón
authors.forename: Elsa
authors.initials: E
authors.lastname: Zotta
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Fellet
authors.forename: Ana M
authors.initials: AM
authors.lastname: Balaszczuk
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D051398:Aquaporin 1 / Q000378:metabolism*; D001823:Body Composition; D001835:Body Weight; D004727:Endothelium / Q000378:metabolism; D006325:Heart Atria / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism; D006706:Homeostasis; D020896:Hypovolemia / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D014867:Water / Q000008:administration & dosage*; D014868:Water Deprivation / Q000502:physiology*; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: C496022:Aqp1 protein, rat; D014867:Water; D051398:Aquaporin 1