EFFECT OF BNP ON RENAL HEMODYNAMICS, TUBULAR FUNCTION AND VASOACTIVE HORMONES IN HUMANS

The effect of a continuous infusion of human brain natriuretic peptide (BNP) was studied in 48 healthy men. The study was randomized, placeb o controlled, and single blind. BNP was given in doses of 1, 2, or 4 p mol.kg(-1).min(-1) for 60 min, and peak values of BNP in plasma were 3 8, 85, and 199 pmol/l, giving increments in plasma as seen in heart or renal failure. BNP infusion increased the urinary flow rate and the e xcretion of sodium in a dose-dependent way. The maximal effects were 65 and +156%, respectively. GFR increased and RPF decreased, the latte r in a dose-dependent manner. Blood pressure, heart rate, angiotensin II, and aldosterone were all unaffected by infusion of BNP, whereas a direct inhibition of renin secretion was seen. With the use of the lit hium clearance technique, we concluded that the tubular site of action is in both the proximal and distal segments, and the major effect on sodium handling is in the distal parts of the nephron.