VASCULAR AQUAPORIN 1 CHANGES AFTER OSMOTIC STRESS AND POSTERIOR REHYDRATION DURING POSTNATAL STAGES

V NETTI; M VATRELLA; A IOVANE; M CHAMORRO; A FELLET; AM BALASZCZUK

Londres

Congreso; 22nd European Meeting on Hypertension and Cardiovascular Protection; 2012

ESH

Aquaporin 1 (AQP1) plays a major role in membrane water transport processes in many tissues in order to maintain cellular osmotic environment and body fluid balance. However, little is known about AQP1 in vascular tissue, which is a tar­get organ for the physiological alterations induced by osmotic stress, particularly during postnatal life. Objective: the aim of the present study was to evaluate vascular AQP1 protein levels and localization in rats subjected to hypovolemic state following water restriction. Method: Male Sprague-Dawley 25 and 50 days old rats were divided in the following groups: R: water restriction during 3 days; C: water ad libitum for 3 days; Rs: water restriction during 3 days + oral rehydration salts (according to WHO) for 3 days. At the end of each experiment, we determined: hematocrit, body weight, systolic blood pressure (SBP) and heart rate (HR); animals were then sacrificed to evaluate in thoracic aorta AQP1 protein levels (Western Blot) and localization (Immunohistochemistry). Results: AQP1 immunohistochemical staining of the thoracic aorta revealed its presence in the vascular endothelium and smooth muscle, this pattern being similar among the studied groups of animals. Western Blot analysis showed that in C groups, AQP1 protein levels were lower in 50 days old animals compared to 25 days old pups. In the youngest group, there were no changes in AQP1 expres­sion with water restriction and posterior rehydration; whereas in 50 days old rats, glycosylated and nonglycosylated AQP1 were only increased after rehydration with oral salts solution (p < 0.01). Conclusion: Water restriction induced a hypovolemic state characterized by significantly decreased body weight and elevated hematocrit, accompanied by hemodynamic alterations. These results suggest that vascular AQP1 may be involved in water homeostasis during rehydration following osmotic stress, being this response different with postnatal growth.