Atrial Natriuretic Peptide (ANP)
A 28 amino acid peptide hormone released by cardiac atrial cells in response to increased blood volume. ANP promotes sodium and water excretion by the kidneys, reduces blood pressure, and opposes the effects of the renin-angiotensin-aldosterone system.
Technical Context
ANP (28 aa) is stored in atrial granules and released in response to atrial wall stretch (increased blood volume/pressure). Its structure includes a 17 amino acid ring formed by a Cys7-Cys23 disulphide bond. ANP acts on NPR-A in kidneys (promoting sodium and water excretion), blood vessels (vasodilation), and adrenal glands (suppressing aldosterone). ANP clearance occurs through NPR-C receptor-mediated internalisation and enzymatic degradation by neutral endopeptidase (neprilysin). The combination neprilysin inhibitor/angiotensin receptor blocker sacubitril/valsartan raises endogenous ANP and BNP levels — demonstrating the therapeutic value of enhancing endogenous natriuretic peptide signalling.