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 natriu retic peptide (BNP) infused at a dose inducing an increase in plasma B NP to pathophysiologic levels, in eight hypertensive patients in a ran domized, placebo-controlled, crossover study. Left ventricular perform ance, cardiac output (echocardiography), heart rate, arterial pressure , glomerular filtration rate (GFR; creatinine clearance), sodium excre tion, 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 cGM P. Plasma BNP levels increased from 2.90 +/- 0.74 to 36.43 +/- 5.51 pm ol/L (P < .01) at the end of the infusion and were still elevated at t he end of the postinfusion period (7.03 +/- 1.41 pmol/L, P < .05). The urinary excretion of cGMP was also significantly higher during BNP in fusion. Left ventricular performance, cardiac output, arterial pressur e, and peripheral vascular resistance were not affected by BNP. Peptid e 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 ob served also in the postinfusion period. The natriuretic effect of BNP was attributable to both an increase in filtered sodium load and a red uction of distal sodium reabsorption. These results suggest that BNP m ay contribute to maintain renal function and sodium excretion in patie nts with essential hypertension.