Atrial natriuretic factor (ANP) is a potent vasoactive substance which is thought to play a key role in cardiovascular homeostasis and has a cGMP stimulating activity. There are two different prepronatriodilatin alleles. One codes for 2 Arginine residues at the C terminus that are cleaved to form the mature peptide, while the other ends in a termination codon immediately after the last codon of the mature peptide. ANP belongs to the natriuretic peptide family.