Atrial natriuretic peptide (ANP) and the homologous B-type natriuretic peptide are cardiac hormones that dilate blood vessels and stimulate natri-uresis and diuresis, thereby lowering blood pressure and blood volume. ANP and B-type natriuretic peptide counterbalance the actions of the renin–angiotensin–aldosterone and neurohormonal systems, and play a cen-tral role in cardiovascular regulation.