Role of renal dopaminergic activity on renal sodium-water metabolism in congestive heart failure.

1. The role of the renal dopaminergic system in water-sodium metabolism in heart failure remains unclear. 2. In this study, the urinary free dopamine excretion (uDA), delivery of L-dopa to renal proximal tubules (plasma L-dopa x creatinine clearance (Ccr)), and the production of dopamine in the kidney [uDA/(plasma L-dopa x Ccr)] were investigated in patients with congestive heart failure (n = 30) and in normal controls (n = 12). In both groups, endogenous Ccr, urinary excretion of sodium (UNaV), fractional excretion of sodium (FENa), plasma noradrenaline concentration (pNA) and plasma L-dopa concentration were also estimated. 3. uDA, plasma L-dopa, delivery of L-dopa and dopamine production in the kidney showed successively lower values in congestive heart failure with progression in NYHA functional class. 4. UNaV (r = 0.458, P < 0.05) and Ccr (r = 0.539, P < 0.01) positively correlated with uDA. Linear correlations were found between left ventricular ejection fraction and uDA (r = 0.574, P < 0.01), pNA (r = -0.495, P < 0.01) or plasma L-dopa (r = 0.423, P < 0.05). 5. From these findings, it was suggested that (i) uDA was clearly suppressed in patients with CHF, and (ii) the possible mechanisms of its suppression might be due to decrease of delivery of L-dopa into the proximal tubules and suppressed production of dopamine from L-dopa in the kidney.