α-Human atrial natriuretic polypeptide is released from the heart and circulates in the body

Abstract

In order to clarify whether or not atrial natriuretic polypeptides are hormones in man, we have measured plasma α-human atrial natriuretic polypeptide (α-hANP)-like immunoreactivity (α-hANP-LI) with or without extraction procedure. α-hANP-LI was detected in plasma extracts from all 5 normal subjects and 7 patients with heart diseases. The α-hANP-LI concentration in normal peripheral plasma was 37.7 ± 7.0 pg/ml (mean ± SE). Plasma concentrations of α-hANP-LI in the coronary sinus obtained by cardiac catheterization were 3 to 10 times higher than those in the peripheral vein, inferior vena cava, right atrium, pulmonary artery and aorta. High performance gel permeation chromatography coupled with a radioimmunoassay (RIA) for α-hANP revealed that α-hANP-LI in normal peripheral plasma eluted at the position corresponding to that of authentic α-hANP without detectable amounts of high molecular weight forms. α-hANP-LI extracted from plasma taken from the coronary sinus of two patients also showed a single peak of α-hANP-LI co-eluting with α-hANP. In contrast, not only α-hANP but γ-hANP and β-hANP, high molecular weight forms, were present in the human atrial tissue. These results indicate that α-hANP is the predominant form of α-hANP-LI in human plasma and that this form generated in the atrial cardiocytes is preferentially released from these cells and circulates in the body.