Renal function in juvenile rats subjected to prenatal malnutrition and chronic salt overload

Dietary sodium may contribute to hypertension and to cardiovascular and renal disease if a primary deficiency of the kidney to excrete sodium exists. In order to investigate whether chronic 1% NaCl in the drinking water changes blood pressure and renal haemodynamics in juvenile Wistar rats subjected to prenatal malnutrition, an evaluation of plasma volume, oxidative stress in the kidney, proteinuria and renal haemodynamics was carried out. Malnutrition was induced by a multideficient diet. Mean arterial pressure, renal blood flow and glomerular filtration rate (GFR) were measured using a blood pressure transducer, a flow probe and inulin clearance, respectively. Plasma volume and oxidative stress were measured by means of the Evans Blue method and by monitoring thiobarbituric acid reactive substances (TBARS) in the kidneys, respectively. Urinary protein was measured by precipitation with 3% sulphosalicylic acid. It was observed that prenatally malnourished rats presented higher values of plasma volume (26%, P < 0.05), kidney TBARS (43%, P < 0.01) and blood pressure (10%, P < 0.01) when compared with the control group. However, they showed no change in renal haemodynamics or proteinuria. Neither prenatally malnourished nor control rats treated with sodium overload presented plasma volume or blood pressure values different from their respective control groups, but both groups presented elevated proteinuria (P < 0.01). The prenatally malnourished group treated with sodium overload presented higher values of kidney TBARS, GFR and filtration fraction (58, 87 and 72% higher, respectively, P < 0.01) than its respective control group. In summary, sodium overload did not exacerbate the hypertension in juvenile prenatally malnourished rats, but induced renal haemodynamic adjustments compatible with the development of renal disease.