[Secretion of atrial natriuretic peptide: relation to atrial pressure and systemic blood pressure]

To determine the influence of atrial pressure, heart rate and loss of atrial-ventricular synchrony in the release of atrial natriuretic peptide (ANP), plasma ANP concentrations were measured by radio-receptor assay in 12 patients during diagnostic cardiac catheterization and in patients with atrial fibrillation and during cardiac pacing. There was a relationship between right atrial pressure and right atrial ANP concentration (r = 0.813, p less than 0.01). Acute loss of atrial-ventricular pacing mode induced an increase in plasma ANP concentration from 44 +/- 8 to 104 +/- 13 pmol/l (n = 11, p less than 0.01) provided that systemic blood pressure was maintained. In contrast, if hypotension developed during ventricular pacing, the ANP levels fell from 68 +/- 11 to 14 +/- 7 pmol/l (n = 5, p less than 0.05) within five minutes despite elevation of atrial pressure. We therefore conclude that atrial pressure and the loss of atrioventricular synchrony may profoundly alter ANP release. The fall in plasma ANP concentration in acute hypotension suggests that, in addition to atrial pressure, ANP release is controlled by a peripheral negative feedback mechanism.