Dietary sodium-induced changes in renal noradrenergic and dopaminergic responses in rats

Effects of dietary sodium on plasma, renal cortical, and urinary dopamine and noradrenaline levels were studied in order to examine the noradrenergic and dopaminergic responses to high sodium intake. Young adult male Sprague-Dawley rats were divided into three groups and were placed on control (0.29%), low (0.05%), and high (3.4%) sodium diets for a period of five weeks. No significant differences were observed in systolic blood pressures, plasma or renal cortical dopamine or noradrenaline, or urinary noradrenaline of any group. Urine volume and urinary elimination of sodium and potassium of the high sodium intake group were significantly greater than that of the control group throughout the experimental period. Urinary excretion of dopamine showed a typical biphasic response with peaks at weeks 1 and 4. These results indicate that high sodium intake affects urinary elimination of dopamine without affecting the sympathetic neural activity, as indicated by the novadrenaline levels in urine, plasma, and renal cortex; and, that excess dietary sodium produces distinctly different dopaminergic and adrenergic responses.