Renal effects of brain natriuretic peptide in patients with congestive heart failure

The effect of a continuous infusion of human brain natriuretic peptide, 2 p mol.min(-1).kg(-1), during 60 min was studied in nine patients with congest ive heart failure and in 10 healthy control subjects. Brain natriuretic pep tide increased from 1.6 to 101 pmol/l in control subjects and from 25 to 17 3 pmol/l in congestive heart failure during infusion. Urinary sodium excret ion increased significantly in both congestive heart failure (60%) and cont rol subjects (71%), but the absolute increase was significantly lower in co ngestive heart failure (27 mu mol/min) than in control subjects (190 mu mol /min). Urinary flow rate did nor change. The lithium clearance technique wa s used to evaluate the segmental tubular function; the distal fractional re absorption of sodium decreased significantly less in congestive heart failu re (DFRNa: -0.8%) than in control subjects (DFRNa: -3.7%). Baseline values for glomerular filtration rate and renal plasma flow were reduced in conges tive heart failure, but brain natriuretic peptide induced no significant ch anges between congestive heart failure and control subjects. Brain natriure tic peptide induced the same absolute increase in secondary messenger cGMP in plasma and urine in both patients and healthy subjects, it is concluded that the natriuretic response to brain natriuretic peptide infusion was imp aired in patients with congestive heart failure compared with healthy subje cts, and it is likely that the im paired natriuretic response was caused by a reduced responsiveness in the distal part of the nephron.