Age-related cardiovascular nitric oxide activity in water deprived rats.

ARZA P, FELLET A, ARRANZ C, BALASZCZUK

Milán, Italia

Congreso; XVII European Meeting on Hypertension; 2007

Objective: to investigate the role nitric oxide (NO) pathway in the cardiovascular adaptation in 2 and 12 months dehydrated rats. Design and Method: Sprague Dawley animals were divided in two experimental groups (n=9/group): Control group: rats had continuous access to both food and water; Water-deprived group: rats were deprived of water for 24, 48 or 72 hours but had continuous access to food. All animals were placed in the metabolic cage for the adaptation of the environment two days before the beginning of the experiments. Systolic blood pressure (SBP, mmHg); NADPH diaphorase activity was evaluated in right atria (A), left ventricle (V) and thoracic aorta segments (TA). Parameters were evaluated after the adaptation period and at the end of the experimental time. Results: rats of 2 months: Water restriction increases SBP at 48 and 72 hours compared with basal values (basal: 114±2; 48 h: 127±3* and 72 h: 127±3*, respectively *P<0.05).Water deprivation reduced NOS activity in A at 24 and 48 hours (57% and 48 %, respectively). However, a rise of 32% was observed at 72 hours. V NOS activity did not change in the experimental groups. TA NOS activity increased in endothelium (E) at 48 and 72 hours (71% and 63% respectively). Meanwhile, in the aorta smooth muscle (M) increased only at 72 hours of water deprivation (88%). Rats of 12 months: Water restriction reduced SBP in the experimental groups compared with basal values (basal: 119±1; 24 h: 107±2*; 48 h: 106±3* and 72 h: 100±3*, respectively *P<0.05). A NOS activity rose at 24, 48 and 72 hours of water restriction (18%, 23% and 27% respectively). V NOS activity showed increased the three experimental groups ( 67%, 51% and 39 %).Water deprivation did not change E NOS activity meanwhile rose in M at 24 hours (3%) but decreased it at 72 hours compared with control animals (16%). Conclusion: Changes in arterial blood pressure and activation of cardiovascular nitric system induced by water deprivation are depending on age. Alterations of the latter would be involved in the cardiovascular adaptation against the volume depletion in the young animals as in the adults. Water deprivation is a physiological stress that triggers a different sequence of events to conserve body fluids and cardiovascular homeostasis in young and adult animals.