Renal effects of dopamine and ANP in high volume expanded rats

Both dopamine (DA) and atrial natriuretic peptide (ANP) have been postulate d to exert similar effects on the kidney, participating in the regulation o f body fluid and sodium homeostasis. In the present study, experiments were performed in anesthetized and isotonic sodium chloride volume expanded rat s. After acute volume expansion at 15 % of body weight during 30 min, glome rular filtration rate, urine output, sodium excretion, fractional sodium ex cretion, proximal and distal sodium excretion and blood pressure were measu red. In additional groups we administered ANP or haloperidol or the combina tion of both to volume expanded animals. Blockade of DA receptors with halo peridol, attenuated diuretic and natriuretic responses to volume load. Prox imal sodium excretion was not modified by haloperidol in all experimental g roups of rats. Reduction in distal tubular excretion was induced by haloper idol in saline infusion expanded rat but not in ANP treated expanded animal s. In conclusion, when exaggerated volume expansion is provoked, both DA an d ANP exert renal tubular events, but ANP have a major central role in the regulation of renal sodium handling.