Atrial natriuretic peptide in recipients of human orthotopic heart transplants.

Atrial natriuretic peptide (ANP) has been proposed to play a role in the maintenance of fluid and electrolyte homeostasis. ANP can be secreted in response to atrial stretch, and right atrial pressure has been proposed to control its secretion in vivo. This study was designed to characterize plasma immunoreactive (IR)-ANP in heart transplant recipients and to determine if IR-ANP levels in these patients correlate with cardiac filling pressures. Nineteen heart transplant recipients were studied during endomyocardial biopsy (group 1), and 20 patients with symptoms of coronary artery disease were studied during cardiac catheterization (group 2). Central venous blood samples and right heart catheterization data were obtained in each patient. IR-ANP levels were measured with a radioimmunoassay for alpha human ANP in extracted plasma samples. There were no differences between groups 1 and 2 in right atrial pressure (6.5 +/- 0.8 versus 6.1 +/- 0.6), pulmonary capillary wedge pressure (13.3 +/- 1.2 versus 11.2 +/- 1.3), mean pulmonary artery pressure (18.0 +/- 1.2 versus 18.2 +/- 1.3), or cardiac index (2.8 +/- 0.0 versus 2.8 +/- 0.1), but patients in group 1 had a higher mean blood pressure (110.6 +/- 2.4 versus 98.3 +/- 3.1, p less than 0.001). Plasma IR-ANP levels in heart transplant recipients were higher than normal (217.0 +/- 28.1 versus 19.2 +/- 2.1 pg/ml, p less than 0.001) and higher than in cardiac catheterization patients (217.0 +/- 28.1 verus 71.1 +/- 11.5 pg/ml, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)