title: Hypovolemic state: age-related influence of water restriction on cardiac nitric oxide synthase in rats.
abstract: OBJECTIVE
  We have assessed the influence of water restriction stress on the nitric oxide (NO) synthase in heart and aorta tissues in young 2-month-old and middle-aged 12-month-old rats.
  
  
  METHODS
  Animals were divided into control and 24- and 72-h water-deprived groups. We evaluated systolic blood pressure (SBP), biochemical parameters, nitrate and nitrite urinary excretion (UNOx), NADPH-diaphorase activity, and protein levels of NOS in the right atria, left ventricle, and thoracic aorta tissues.
  
  
  RESULTS
  Water restriction during 72 h increased SBP (16%) in 2-month-old rats but decreased it after 24 and 72 h (9 and 15%, respectively) in 12-month-old rats. Atria, aorta endothelium, and smooth muscle NOS activity increased (32, 63, and 88%, respectively) only after 72 h of water restriction in 2-month-old rats. It also increased not only after 72 h but also after 24 h in atria (27 and 18%, respectively) and in ventricle (39 and 67%, respectively) in 12-month-old rats. Meanwhile, in this group's aorta smooth muscle, the enzyme activity decreased (16 and 7%, respectively). A major difference seen between ages was the changes in UNOx excretion, which decreased in the younger in 24 and 72 h (47 and 81%, respectively) and increased in the middle-aged rats (193 and 389%, respectively). Water restriction did not change cardiovascular endothelial and neuronal NOS protein levels in any group.
  
  
  CONCLUSIONS
  NO pathways could contribute to the development of age-related cardiovascular adaptation to volume depletion induced by water restriction.
authors.affiliation: Department of Physiology, School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD, Buenos Aires, Argentina. afellet@ffyb.uba.ar
authors.forename: Andrea Lorena
authors.initials: AL
authors.lastname: Fellet
authors.forename: Patricia Raquel
authors.initials: PR
authors.lastname: Arza
authors.forename: Myriam
authors.initials: M
authors.lastname: Nuñez
authors.forename: Cristina Teresa
authors.initials: CT
authors.lastname: Arranz
authors.forename: Ana María
authors.initials: AM
authors.lastname: Balaszczuk
mesh_terms: D000222:Adaptation, Physiological; D000375:Aging / Q000473:pathology*; D000818:Animals; D001013:Aorta, Thoracic / Q000201:enzymology; D001794:Blood Pressure; D004730:Endothelium, Vascular / Q000201:enzymology; D006352:Heart Ventricles / Q000201:enzymology*; D020896:Hypovolemia / Q000201:enzymology / Q000473:pathology*; D008297:Male; D023421:Models, Animal; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009566:Nitrates / Q000652:urine; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D009573:Nitrites / Q000652:urine; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological; D014867:Water / Q000502:physiology*
chemical_list: D009566:Nitrates; D009573:Nitrites; D014867:Water; D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase