Biological Activity of a Synthetic Alpha-Human Atrial Natriuretic Polypeptide in Anesthetized Dogs

It has been reported that crude or semipurified extracts of atrial tissue contain peptide-like substances which produce a marked diuresis and natriuresis, in intact rats (1–3). Several investigators determined the amino acid sequences of atrial natriuretic polypeptides in humans (4) and rats (5–7). Human atrial tissues contain three components (α, β and γ) of the polypeptides that possess both natriuretic and smooth muscle relaxant activities (4). Chemical synthesis of a 28-amino acid polypeptide, designated as alpha-human natriuretic polypeptide (α-hANP), make feasible a quantitative estimation of the biological activities of the peptide (4). In the present experiment, effects of α-hANP on renal vasculature and urine formation were investigated in anesthetized dogs, and the site of action of the peptide within the nephron was assessed from the pattern of water and electrolytes excretion during water diuresis and hydropenia.