DIFFERENTIAL REGULATION OF BRAIN AND ATRIAL NATRIURETIC PEPTIDES IN HEMODIALYSIS-PATIENTS

We investigated the effect of volume overload on the plasma concentrations of brain and atrial natriuretic peptides as well as cyclic GMP, using specific radioimmunoassays, in 49 patients with chronic renal failure on regular hemodialysis treatment. Markedly elevated levels of the brain (16.2 +/- 1.3 pmol/l) as well as atrial (39.0 +/- 2.8 pmol/l) natriuretic peptide in plasma were found before the dialysis session, as compared to healthy volunteers (range for brain natriuretic peptide, 0.7-7.3 pmol/l, mean level 2.55 +/- 0.32 (SEM) pmol/l). In contrast to the levels of the atrial natriuretic peptide, those of the brain natriuretic peptide were lowered less efficiently by the dialysis procedure: The mean pre-/postdialytic concentration differences were -1.5 pmol/l and -14.2 pmol/l for brain and atrial natriuretic peptide, respectively. The concentrations of the intracellular mediator of the natriuretic peptides, cyclic GMP, were found to be excessively elevated (34.8 +/- 2.8 nmol/l) and returned to near-normal values (12.4 +/- 1.6 nmol/1) at the end of the dialysis session. Concentrations of BNP in plasma of the patients were well correlated to those of ANP. Significant though less marked correlations were also observed between the plasma concentrations of cyclic GMP and BNP, or ANP, respectively. In contrast to those of ANP, pre-/postdialysis differences in plasma BNP concentrations were not correlated to the extent of volume reduction during dialysis. Our findings show that pathophysiologic states resulting in elevations of the plasma concentrations of the atrial natriuretic peptide can also lead to increased levels of the brain natriuretic peptide. Furthermore, alterations in volume and electrolyte balance, as they are encountered in hemodialysis patients, may have a different impact on the various members of the natriuretic peptide family.