Atrial natriuretic peptide: heart-derived hormone that regulates blood volume and sodium

Mechanism and main effects

ANP binds to specific natriuretic peptide receptors on vascular, renal and adrenal cells, activating intracellular guanylate cyclase and raising cyclic GMP levels. Through these pathways it promotes vasodilation, increases urinary sodium excretion (natriuresis) and urine production (diuresis), and suppresses components of the renin–angiotensin–aldosterone system. In the kidney, ANP alters glomerular hemodynamics and tubular transport to increase the loss of salt and water, helping to reduce circulating volume and lower blood pressure (blood pressure).

Principal actions

• Vasodilation of systemic resistance vessels, lowering vascular resistance.
• Enhanced glomerular filtration and reduced tubular sodium reabsorption, producing natriuresis and diuresis.
• Inhibition of renin release and reduced aldosterone secretion, countering fluid-retaining hormones such as those in the renin–angiotensin–aldosterone system; ANP inhibits renin, an enzyme central to that cascade.

Clinical significance and distinctions

ANP is related to other natriuretic peptides such as brain (B-type) natriuretic peptide (BNP) and C-type natriuretic peptide (CNP); BNP, though originally named after its discovery in brain tissue, is secreted mainly from ventricular myocardium under pressure or volume overload and is widely used as a biomarker in heart failure (BNP and related peptides). Measurement of natriuretic peptide levels aids diagnosis and prognosis in cardiovascular disease. Therapeutic applications of natriuretic peptides have been explored, especially in acute decompensated heart failure, though routine clinical use varies by region.

History and notable facts

ANP was identified in the early 1980s and was among the first hormones shown to originate in the heart rather than in classic endocrine glands. The natriuretic peptide family illustrates how the heart functions as an endocrine organ as well as a pump. Research continues into receptor subtypes (NPR-A, NPR-B, NPR-C) and how modulating this system can treat hypertension, heart failure and fluid overload states.

For concise summaries and clinical guidelines consult sources on cardiovascular physiology and heart-failure biomarkers (vasodilator overview, hormone function, BNP information, renal effects and blood pressure implications). For molecular and enzymatic context see entries on renin and related enzymes.