Objective: The aim of the present study was to determine the vasoactive effects of brain natriuretic peptide (BNP) as compared to those of atrial natriuretic peptide (ANP) in normal man.
Methods: Ten healthy male subjects (median age 21 (20-23) year) were studied twice. In the first study equimolar doses (1, 3, and 10 pmol/dl/min) of both BNP and ANP (in random order and double blind) were infused into the brachial artery of the non-dominant arm with a 1-h wash-out period in between. In the second study two BNP (n = 5) or ANP (n = 5) dose-response curves were performed in order to assess the repeatability of the BNP/ANP infusions. To this end, BNP and ANP were infused in the same equimolar doses as in the first protocol. Forearm blood flow (FBF) was determined by venous occlusion plethysmography before and during infusions.
Results: BNP increased the FBF ratio (infused/contralateral arm) by 6%, 17%, and 48%, respectively (p < 0.05), while ANP increased the FBF ratio by 4%, 58%, and 133% (p < 0.001). The slopes of the BNP dose-response curves differed significantly from those of the ANP curves (18.1 versus 43.2; p = 0.022). No differences were observed between the repeated dose-response curves of either BNP or ANP.
Conclusions: The present data demonstrate that BNP induces a dose-dependent vasodilatation in man. On a molar basis, however, this vasodilatation is significantly less than the vasodilatation induced by ANP. These differences may be related to differences in natriuretic-peptide-receptor affinity. Furthermore, our data show that the vasoactive effects of both BNP and ANP are repeatable in time.