Plasma atrial natriuretic peptide in health and disease.

The plasma concentration of atrial natriuretic peptide (ANP) in 16 healthy subjects on a free diet was 41 +/- 23 pg ml-1 (mean +/- SD) when upright and 58 +/- 27 pg ml-1 in the supine position (P less than 0.05), which confirms the concept that the supine position raises plasma ANP. Water immersion to the neck for 2 h caused a brisk diuresis, natriuresis and raised plasma ANP in 8 healthy subjects, suggesting that ANP is a mediator of diuresis and natriuresis during immersion. Dynamic exercise (50-200 W per 4 min) on a bicycle ergometer caused a gradual increase in plasma ANP in 6 healthy males, with a close correlation between the increases in plasma ANP and heart rate (r = 0.96). Thus, plasma ANP levels are increased in healthy subjects by stimuli causing an increased preload and possibly by tachycardia itself. Markedly raised plasma levels of ANP were found in patients with congestive heart failure, and upright posture caused a further rise of plasma ANP which correlated with the increase in heart rate (r = 0.87). High plasma ANP concentrations were also found in 25 patients with end-stage renal failure maintained on haemodialysis. When these patients were subdivided into those with concomitant heart failure and those with normal cardiac function, changes in plasma ANP correlated with predialysis weight gain and weight loss during dialysis, but only in patients without heart failure. In 9 infants treated by operative or pharmacological closure of persistent ductus arteriosus, high pre-treatment plasma ANP values were lowered by successful therapy, and plasma ANP correlated with the degree of left atrial distension.(ABSTRACT TRUNCATED AT 250 WORDS)