SYSTEMIC HEMODYNAMICS AND RENAL-FUNCTION DURING BRAIN NATRIURETIC PEPTIDE INFUSION IN PATIENTS WITH ESSENTIAL-HYPERTENSION

We assessed the cardiovascular and renal effects of human brain natriuretic peptide (BNP) infused at a dose inducing an increase in plasma BNP to pathophysiologic levels, in eight hypertensive patients in a randomized, placebo-controlled, crossover study. Left ventricular performance, cardiac output (echocardiography), heart rate, arterial pressure, glomerular filtration rate (GFR; creatinine clearance), sodium excretion, intrarenal sodium handling (lithium clearance method), and urine flow rate were measured in the infusion and postinfusion periods (1 h each), together with plasma BNP and the urinary excretion rate of cGMP. Plasma BNP levels increased from 2.90 +/- 0.74 to 36.43 +/- 5.51 pmol/L (P < .01) at the end of the infusion and were still elevated at the end of the postinfusion period (7.03 +/- 1.41 pmol/L, P < .05). The urinary excretion of cGMP was also significantly higher during BNP infusion. Left ventricular performance, cardiac output, arterial pressure, and peripheral vascular resistance were not affected by BNP. Peptide infusion induced a significant increase in GFR (placebo, 115 +/- 24; BNP, 147 +/- 19 mL/min), sodium excretion (placebo, 129 +/- 40; BNP, 243 +/- 60 mu mol/min), and urine flow rate. All these effects were observed also in the postinfusion period. The natriuretic effect of BNP was attributable to both an increase in filtered sodium load and a reduction of distal sodium reabsorption. These results suggest that BNP may contribute to maintain renal function and sodium excretion in patients with essential hypertension.