Circulating beta-atrial natriuretic factor in congestive heart failure in humans.

BACKGROUND

beta-Atrial natriuretic factor (beta-ANF) is an antiparallel dimer of alpha-ANF (alpha-ANF) with diminished cyclic GMP generation in vitro. To date, the presence of beta-ANF in the circulation of humans with severe congestive heart failure (CHF) remains controversial. The current study was designed to determine the presence and magnitude of circulating beta-ANF in severe CHF, to correlate plasma beta-ANF with the degree of ventricular dysfunction, and to investigate the role of human plasma and atrial tissue in the degradation of beta-ANF.

METHODS AND RESULTS

Venous plasma samples were obtained from patients (n = 12) with severe CHF and normal volunteers (n = 8). Total plasma ANF was measured by radioimmunoassay. alpha-ANF and beta-ANF in nonextracted plasma were separated by gel filtration chromatography using a P-6 column. Right atrial tissue samples (n = 5) were collected from a different group of patients at the time of open-heart surgery. 125I beta-ANF and I125 ANF were incubated with atrial tissue or plasma. The corresponding peak areas of beta-ANF were determined by Tamaya Digital Planimeter. beta-ANF represented 61% of total plasma ANF in CHF patients and was not detected in normal human plasma. The elevation of beta-ANF correlated with the severity of ventricular dysfunction. Thirty percent of beta-ANF and 100% alpha-ANF were converted to smaller peptide fragments in atrial tissue no conversion in plasma.

CONCLUSIONS

beta-ANF is the principal form of circulating ANF in patients with severe CHF and correlates with the degree of left ventricular dysfunction. beta-ANF is not generated from alpha-ANF and may be degraded rapidly in atrial tissue to smaller peptide fragments that do not occur in plasma. As beta-ANF is reported to have reduced biological action, the current studies may support the conclusion that the ANF system in CHF has reduced functional activity despite increases in circulation concentrations.