Atrial Natriuretic Peptide (ANP)

Atrial natriuretic peptide (ANP) is a natriuretic peptide hormone with 28 amino acids, generated in the heart to regulate atrial stretch and hypertension caused by hypervolemia. ANP is found in mammals, amphibians and bony fishes. It is synthesized as a precursor, encoded by the NPPA gene in humans and characterized by a 17-amino acids ring formed by a disulfide bond between two cysteines. There are three structurally related hormones/paracrine factors in the natriuretic peptide family: ANP, BNP, and CNP, all of which share similar amino acid ring structures.

The main function of ANP include stimulating natriuresis and diuresis in the kidney and relax vascular smooth muscles, which controls blood pressure and volume. This function is performed by the transmembrane receptor–natriuretic peptide receptor A (NPR-A), also known as guanylyl cyclase A (GC-A). After ANP binds to GC-A, the second messenger cyclic guanosine monophosphate (cGMP) is produced. The biological effects of ANP are then mediated by the activation of protein kinase G (PKG) and cGMP-gated ion channels. Moreover, ANP also inhibits the production of aldosterone in the adrenal glands.