Bioactivity and interactions of adrenomedullin and brain natriuretic peptide in patients with heart failure

Plasma concentrations of the recently discovered hormones adrenomedullin (ADM), from vascular tissue, and brain natriuretic peptide (BNP), secreted by myocardium, are elevated-in patients with heart failure. We tested the hypotheses that short-term increments in circulating levels of these hormones, within the pathophysiological range, would have biological effects and that the 2 hormone systems interact. Eight patients with heart failure (left ventricular ejection fractions <35%) received 4-hour infusions of BNP (30 pmol.kg(-1).min(-1)) alone, ADM (2.7 pmol.kg(-1).min(-1) and 5.4 pmol.kg(-1).min(-1) for 2 hours each) alone, ADM and BNP combined, and placebo. BNP and ADM infusions raised plasma levels of the respective peptide within the pathophysiological range. Arterial blood pressure fell (P<0.05) with all peptide infusions, but cardiac output was unchanged. Heart rate increased with ADM and combined infusions (P<0.01). Sodium excretion rose (P<0.05); and creatinine clearance was sustained during both BNP and combined infusions. Urine volume increased in response to BNP alone (P=0.02). Despite a >2-fold increase in plasma renin with both ADM and combined infusions (P<0.05), plasma aldosterone remained lower than time-matched placebo levels, plasma noradrenaline was increased by combined, BNP, and higher dose ADM infusions (P<0.05). ADM suppressed plasma cGMP (P<0.05) and inhibited the plasma cGMP response to BNP (P<0.05). The vascular hormones ADM and BNP, produced by myocardium, at plasma concentrations within the pathophysiological range have hemodynamic, renal, and hormonal effects and measurable interactions in patients with heart failure.