Epigenetic studies suggest that diseases that develop in adulthood are related to certain conditions to which the individual is exposed during the initial stages of life. Experimental evidence has demonstrated that offspring born to mothers maintained on high-Na diets during pregnancy have higher mean arterial pressure (MAP) in adulthood. Although these studies have demonstrated the importance of prenatal phases to hypertension development, no evidence regarding the role of high Na intake during postnatal phases in the development of this pathology has been reported. Therefore, in the present study, the effects of Na overload during childhood on induced water and Na intakes and on cardiovascular parameters in adulthood were evaluated. Experiments were carried out in two groups of 21-d-old rats: experimental group, maintained on hypertonic saline (0·3 M-NaCl) solution and food for 60 d, and control group, maintained on tap water and food. Later, both groups were given water and food for 15 d (recovery period). After the recovery period, chronic cannulation of the right femoral artery was performed in unanaesthetised rats to record baseline MAP and heart rate (HR). The experimental group was found to have increased basal MAP (98·6 (SEM 2·6) v. 118·3 (SEM 2·7) mmHg, P, 0·05) and HR (365·4 (SEM 12·2) v. 398·2 (SEM 7·5) beats per min, P, 0·05). There was a decrease in the baroreflex index in the experimental group when compared with that in the control group. A water and Na intake test was performed using furosemide. Na depletion was found to induce an increase in Na intake in both the control and experimental groups (12·1 (SEM 0·6) ml and 7·8 (SEM 1·1), respectively, P , 0·05); however, this increase was of lower magnitude in the experimental group. These results demonstrate that postnatal Na overload alters behavioural and cardiovascular regulation in adulthood.Key words: Hypertension: Water intake: Sodium intake: Postnatal periodThe maintenance of a stable internal environment is the main target of all physiological processes (1,2) , which is positively correlated with the regulation of ionic concentrations in the intracellular and extracellular compartments. Among the different types of inorganic salts present in the body fluids, NaCl is the most predominantly consumed salt and Na concentration is directly related to the maintenance of body fluid homeostasis (1,2) . Changes in Na concentrations result in an osmotic flux between the intracellular and extracellular compartments. Na influx or efflux affects the concentrations of all the other components in these compartments. Therefore, it is not surprising that many homeostatic mechanisms exist to maintain plasma Na concentrations with a limited rate of variation.The regulation of blood pressure (BP) involves complex mechanisms, including local, hormonal, neuronal and renal regulation, that, working together, are responsible for the redistribution of blood through changes in peripheral vascular resistance and cardiac output. Experimental evidence has demons...