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

The effect of a continuous infusion of human brain natriuretic peptide, 2 ;pmol·min^-1·kg^-1, during 60 ;min was studied in nine patients with congestive heart failure and in 10 healthy control subjects. Brain natriuretic peptide increased from 1.6 to 101 ;pmol/l in control subjects and from 25 to 173 ;pmol/l in congestive heart failure during infusion. Urinary sodium excretion increased significantly in both congestive heart failure (60%) and control subjects (71%), but the absolute increase was significantly lower in congestive heart failure (27 ;μmol/min) than in control subjects (190 ;μmol/min). Urinary flow rate did not change. The lithium clearance technique was used to evaluate the segmental tubular function; the distal fractional reabsorption of sodium decreased significantly less in congestive heart failure (DFR_Na: -0.8%) than in control subjects (DFR_Na: -3.7%). Baseline values for glomerular filtration rate and renal plasma flow were reduced in congestive heart failure, but brain natriuretic peptide induced no significant changes between congestive heart failure and control subjects. Brain natriuretic 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 impaired in patients with congestive heart failure compared with healthy subjects, and it is likely that the impaired natriuretic response was caused by a reduced responsiveness in the distal part of the nephron.