Sheep Anti-Human Pro-Atrial Natriuretic Peptide (aa 1-30) polyclonal antibody for RIA, ELISA. Atrial natriuretic peptide (ANP), atrial natriuretic factor (ANF), atrial natriuretic hormone (ANH), or atriopeptin is a powerful vasodilator, and a protein (polypeptide) hormone secreted by heart muscle cells.[1][2] It is involved in the homeostatic control of body water, sodium, potassium and fat (adipose tissue). It is released by muscle cells in the upper chambers (atria) of the heart (atrial myocytes) in response to high blood pressure. ANP acts to reduce the water, sodium and adipose loads on the circulatory system, thereby reducing blood pressure.