Further studies on the mechanism of the natriuretic response to low-dose dopamine in man: effect on lithium clearance and nephrogenic cAMP formation.
The effect of intravenous infusion of low-dose dopamine on electrolyte excretion, lithium clearance, nephrogenous cAMP formation and renal haemodynamics was investigated in healthy volunteers. Dopamine significantly increased the urine flow rate by 70.6% and urinary sodium excretion by 72%, but did not change creatinine clearance, PRA or plasma levels of AVP, ANP and cAMP. Renal plasma flow significantly increased by 48.6%; the glomerular filtration rate was not changed. Lithium per se increased basal PRA, but had no effect on the increments of urine flow rate, sodium excretion and renal blood flow induced by dopamine. Dopamine significantly increased the fractional excretion of lithium (representing fractional excretion of sodium at the proximal level). The increase in urinary sodium excretion during dopamine infusion, significantly correlated with the increase in fractional excretion of lithium (r = 0.94; P less than 0.01) and the increase in nephrogenous cAMP formation (r = 0.96; P less than 0.01). No correlation was found between the increase in urinary sodium excretion and the increase in renal blood flow. In conclusion, this study confirms that low-dose dopamine increases renal blood flow and urinary sodium excretion in healthy volunteers. This natriuretic response appears to be due to interaction with proximal tubular dopamine receptors, which are positively coupled to adenylate cyclase.
Schoors
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DF
Department of Pharmacology, Vrije Universiteit Brussel, Belgium.
Dupont
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AG
D000328:Adult; D000242:Cyclic AMP / Q000096:biosynthesis*; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D008094:Lithium / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects; D009318:Natriuresis / Q000187:drug effects*
D008094:Lithium; D000242:Cyclic AMP; D004298:Dopamine