Purification, sequencing and synthesis of natriuretic and vasoactive rat atrial peptide

Mammalian atria contain potent natriuretic and diuretic substances 1,2 which exist in high- and low-molecular-weight forms 2,3 and which appear to be associated with atrium-specific granules 4 . The natriuretic effect of atrial extract is largely accountable for by its renal haemodynamic effects 5–7 ; atrial extracts also antagonize hormone- and non-hormone-induced contraction of the isolated rabbit aorta 8–10 and isolated rat kidney vasculature 6 . We have completely purified a low-molecular-weight natriuretic and vasoactive substance from rat atria and characterized it as a 24-amino acid peptide. Synthetic peptide, produced by solid-phase synthesis, mimics biological effects of crude atrial extract and purified peptide; its activity is enhanced by slow oxidation, suggesting a disulphide (Cys 4–Cys 20) configuration for the native peptide. If secreted into blood, this atrial natriuretic peptide (‘auriculin B‘) could be a novel peptide hormone of considerable importance to renal and cardiovascular homeostasis.