THE EFFECT OF INTRAVENOUS SALINE LOADING ON PLASMA-LEVELS OF BRAIN NATRIURETIC PEPTIDE IN MAN

Objective: Recent evidence suggests the presence of a dual natriuretic peptide system consisting of atrial natriuretic factor (ANF) from the atrium and brain natriuretic peptide (BNP) from the ventricle. Discre te roles have been postulated for these two natriuretic peptides in th e control of circulatory homeostasis. We have therefore compared the r elease of ANF and BNP in response to an acute saline load to explore a differential pattern of release for the two natriuretic peptides in m an. Design: The effects of an acute saline infusion on plasma ANF and BNP concentrations were studied in 10 normal male volunteers. Methods: Subjects were studied on two study days in the semirecumbent position . An acute intravenous saline infusion (250 ml/min) of 18 ml/kg isoton ic sodium chloride-potassium chloride solution was administered on one of the two study days. No infusion was administered on the other day as a control. Results: Plasma ANF concentrations increased significant ly (P < 0.01) with saline loading without any detectable changes in pl asma BNP concentrations up to 60 min following infusion. Heart rate an d systolic and diastolic blood pressure were unchanged after saline lo ading. Conclusions: We have shown that an acute intravenous saline loa d causes an increase in plasma ANF concentrations with no detectable i ncrease in plasma BNP at least up to 60 min after the acute saline loa d in man. These results support the view that the release of ANF and B NP may be regulated differently, especially with regard to the time re quired for the acute release of each peptide.