CARDIAC AQUAPORIN 1 DURING OSMOTIC STRESS INDUCED BY WATER RESTRICTION

V. NETTI; M. VATRELLA; M. CHAMORRO; D. VIVES

Milan

Congreso; 21st European Meeting on Hypertension; 2011

Aquaporin 1 (AQP1) is an ubicuous water channel protein involved in the maintenance of cellular osmotic environment and body fluid balance. However, little is known about AQP1 in the heart, 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 ventricular AQP1 protein levels and localization in rats subjected to hypovolemic state following water restriction. Method: male Sprague-Dowley 25 days old rats were divided in the following groups: R: water restriction during 3 days; C: water ad libitum for 3 days; Rsol: 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 ventricular AQP1 protein levels (Western Blot) and localization (Immunohistochemistry). Results: AQP1 immunohistochemical staining of the left ventricle revealed its presence in vascular endothelium and endocardium, this patterm being similar amog the studied groups of animals. Western Blot analysis showed that water restriction increased non-glycosylated AQP1 compared to C (p<0.05), whereas hydration with oral salts increased glycosylated AQP1 compared to both C and R (p<0.01). Conclusion: Water restriction induced a hypovolemic state characterized by significantly decreased body weight and elevated hematocrit, accompanied by hemodinamic alterations. The results suggest that cardiac AQP1 may be involved in water homeostasis during osmotic stress, showing a diferential expression pattern in response to hydration status, without changing its localization.