VARIABLE PATTERNS OF ATRIAL-NATRIURETIC-PEPTIDE SECRETION IN MAN

Peripheral circulating levels of atrial natriuretic peptide may exhibi t short-term variation compatible with a pulsatile pattern of secretio n. We obtained samples every 2 min for 90 min from the antecubital vei n of 16 patients with chronic cardiac failure and 13 controls. Overall levels were higher in the patients (median and quartiles 230 (125,325 ) vs. 26 (16,48) ng l(-1); P < 0.001). In both groups there was consid erable variability, with 10 (2-12) peaks, 9 (7-15) troughs (both defin ed as > 2 SD from the mean) and 16 (13-18) pulses (defined by computer ) during the sampling period in controls, and a similar number in pati ents. We then carried out simultaneous sampling in the pulmonary arter y, femoral artery and peripheral vein in eight subjects with normal ca rdiac function and six patients with impaired function due to valvular heart disease. The pattern of variability was preserved in all three sites in both groups, suggesting intermittent secretion rather than va riable breakdown of the peptide in the lung. No changes in right atria l pressure or heart rate were observed to coincide with the variations , but levels of the peptide in the pulmonary artery correlated with ri ght atrial pressure in patients (r = 0.87; P < 0.05). The mechanism of such periodicity and its pathophysiological importance remain unknown .