ANP (Atrial Natriuretic Peptide)
Cardiovascular / RenalAlso known as: Atrial Natriuretic Peptide, Atrial Natriuretic Factor, ANF, Atriopeptin, Cardionatrin
Mechanism
ANP is a heart hormone released by the atria when they are stretched by excess blood volume. It acts as the body's natural blood pressure reducer — it makes the kidneys excrete more sodium and water (natriuresis/diuresis), relaxes blood vessels, and opposes the renin-angiotensin-aldosterone system. Elevated ANP is a clinical marker of heart failure.
Technical detail
ANP is a 28-amino-acid cyclic peptide (17-residue ring via Cys7-Cys23 disulfide) secreted from atrial cardiomyocyte granules in response to atrial wall stretch. It binds natriuretic peptide receptor A (NPR-A/GC-A), a membrane-bound guanylyl cyclase, generating cGMP which activates PKG. Effects include: renal afferent arteriolar dilation and efferent constriction (increasing GFR and natriuresis), inhibition of sodium reabsorption in collecting ducts, direct vasodilation via PKG-mediated MLCP activation, suppression of renin secretion, suppression of aldosterone synthesis, and inhibition of ADH release. Cleared by NPR-C (clearance receptor) and neprilysin.