Renal effects of dopamine and ANP in high volume expanded rats

Abstract

A. M. BALASZCZUK and A. L. FELLET. Renal effects of dopamine and ANP in high volume expanded rats. J. Physiol. Biochem., 57 (2), [81][82][83][84][85][86][87][88] 2001.Both dopamine (DA) and atrial natriuretic peptide (ANP) have been postulated to exert similar effects on the kidney, participating in the regulation of body fluid and sodium homeostasis. In the present study, experiments were performed in anesthetized and isotonic sodium chloride volume expanded rats. After acute volume expansion at 15 % of body weight during 30 min, glomerular filtration rate, urine output, sodium excretion, fractional sodium excretion, proximal and distal sodium excretion and blood pressure were measured. In additional groups we administered ANP or haloperidol or the combination of both to volume expanded animals. Blockade of DA receptors with haloperidol, attenuated diuretic and natriuretic responses to volume load. Proximal sodium excretion was not modified by haloperidol in all experimental groups of rats. Reduction in distal tubular excretion was induced by haloperidol in saline infusion expanded rat but not in ANP treated expanded animals. In conclusion, when exaggerated volume expansion is provoked, both DA and ANP exert renal tubular events, but ANP have a major central role in the regulation of renal sodium handling.An acute increase in sodium intake produced by volume expansion with sodium chloride has shown to evoke a marked diuretic and natriuretic response (29). The mediators of this homeostatic mechanism include certain neural and hormonal systems such as atrial natriuretic peptide (ANP) and dopamine (DA) (18). However, the importance of each of these substances in different physiological conditions has not been well defined. Of particular interest is the observation that DA