Pulsatile secretion of atrial natriuretic peptide and brain natriuretic peptide in healthy humans

Both atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are involved in sodium and water homoeostasis in healthy humans. The plasma concentrations of the natriuretic peptides can be used to differentiate between dyspnoea of cardiac and pulmonary origin, and the degree of elevation of the peptide levels in the plasma in heart failure is a measure of the severity of the disease. However, the patterns of secretion of ANP and BNP are not clear either in healthy humans or in patients. The purpose of the present study was to test the hypotheses that both ANP and BNP are secreted in pulses in healthy humans, and that this phenomenon can be revealed by determination of ANP and BNP in peripheral venous blood samples. In 12 healthy subjects, blood samples were drawn every 2 min through an intravenously inserted plastic needle over a period of 2 h. Plasma concentrations of ANP and BNP were determined by RIAs, and the results were analysed for pulsatile behaviour by Fourier transformation. Pulsatile secretion of ANP was seen in 10 out of 12 subjects [ν = 0.028 min^-1 (median; range 0.013–0.047 min^-1), i.e. a pulse of ANP with an interval of 36 min (range 21–77 min)]. Pulsatile secretion of BNP was seen in nine out of 12 patients [ν = 0.021 min^-1 (range 0.013–0.042 min^-1), i.e. a pulse of BNP with an interval of 48 min (range 24–77 min)]. The main conclusion is that the secretion patterns of both ANP and BNP are pulsatile in most healthy humans. Consequently, it is important to study whether pulsatile secretion also occurs in heart failure in order to obtain the most informative predictive values both in the differential diagnosis of dyspnoea and in the evaluation of the severity of the disease.