Renal nitric oxide in dehidration induced by chronic water deprivation

ARZA PATRICIA; DA ROSA P; TOSCANI M; PRUFLING A; ARRANZ CRISTINA; FELLET ANDREA; COSTA MARIA DE LOS ANGELES; BALASZCZUK ANA MARÍA

Berlín. Alemania.

Congreso; Eighteenth European Meeting on Hypertension.; 2008

European Society of Hypertension. International Society of Hypertension.

Objectives: Water deprivation leads to a hydroelectrolitic disbalance that triggers the activation of numerous neurohumoral systems, including nitric oxide (NO) system. It is known that NO is involved in the renal adaptative response in several physiological and pathological conditions. NO role in the pathogenesis of hypovolemic state induced by chronic dehydration remains to be defined. The aim was: 1) to evaluate the effect of chronic water deprivation on renal NO system, and 2) to study the potential effect of a subsequent hydration on the alterations induced by this hypovolemic state. Methods: Male Sprague-Dowley rats (200g) were divided in: E1: water restriction during 3 days + 1 day of hydration (1 cycle), the cycle was repeated 8 times (32 days); C1: water ad libitum during 32 days; E2: 8 cycles of water restriction + water ad libitum during 1 month. We determined: body weight, systolic blood pressure (SBP), hematocrit, plasmatic urea and osmolality and urinary minute volumen (UMV) before and at the end of each experiment. Animals were sacrificed to evaluate NOS activity (14C L-arginina) in renal medulla (RM) and cortex (RC). C1 E1 E2 Body weight (g) 285±10 195±6* 325±8# SBP (mmHg) 108±2 78±4* 102±3# Henatocrit (%) 48±1 53±1* 49±1# Plasmatic Osmolality (mOsm/Kg H2O) 316±3 357±10* 317±7# Plasmatic urea (g/L) 0.36±0.02 1.37±0.17* 0.39±0.03# RM NOS activity (pmol/g tissue.min) 556±20 402±18* 515±16# RC NOS activity (pmol/g tissue.min) 435±12 349±16* 400±15# Conclusion: Chronic water restriction increased plasmatic osmolality and decreased body weight (32%), plasmatic volume (10%) associated with a reduction in SBP and renal NOS activity. These parameters recovered basal values after one month of oral hydration. According to our results, we suggest that renal NO system activity depends