atrial natriuretic peptide (ANP), a hormone involved in natriuresis and the regulation of renal and cardiovascular homeostasis. It is synthesized as a prohormone in the granules of the myocytes of the atrium and is released into the circulation in response to atrial dilation or increased intravascular fluid volume. It causes natriuresis, diuresis, and renal vasodilation; reduces circulating concentrations of renin, aldosterone, and antidiuretic hormone; and thereby normalizes circulating blood pressure and volume. Also called atrial natriuretic factor.
