Purification of three rat atrial natriuretic factors and their amino acid composition

Abstract
A natriuretic factor has been described in the specific granules of rat atria. We have purified three factors which seem to be low‐M r peptides. They have been purified by means of acid extraction, octadecyl Sep‐Pak cartridges, and chromatography on Bio‐Gel P‐10, CM Bio‐Gel A, Mono S and reverse‐phase high‐performance liquid chromatography columns. The factors contain 26, 31 and 33 amino acids and may have been partially degraded during isolation. They are all 3 biologically active and the shorter one is the most active with a specific activity of 450000 units/mg.