Natriuresis does not account for urinary concentration inhability in the chronically undernourished rat

Through different concentrations of sodium in the diet, we investigated whether the natriuresis observed in the DBR rats since weaning resulted from the higher Na + intake or from its lower conservation by the kidney and its effect on the urinary concentration. For this purpose, we used a multicentre diet, locally called the regional basic diet (DBR) and 60 male Wistar rats, treated from weaning with: (i) control diet, by the American Institute of Nutrition (AIN); ii) DBR supplemented with low Na + content (0.06%), the DBR group; (iii) DBR supplemented with normal Na + content (0.3%), the DBRnorm group; iv) DBR supplemented with high Na + content (3.12%), the DBRhiper group. The excretion capacity in relation to sodium intake was similar between these two groups (99.01 ± 0.12 vs 99.02 ± 0.17%). Malnutrition compromised the urinary concentration mechanism.