Cardiovascular Peptides and Heart Function
Gut Peptide Hormones
100 pg/mL
A BNP level above 100 pg/mL in an emergency department patient with shortness of breath has 90% sensitivity for detecting heart failure, transforming how clinicians diagnose cardiac emergencies.
Tsutsui et al., J Cardiac Failure, 2023
Tsutsui et al., J Cardiac Failure, 2023
View as imageYour heart is an endocrine organ. This was not obvious until 1981, when Adolfo de Bold injected atrial muscle extract into rats and observed a rapid, potent diuretic and natriuretic response. That experiment revealed atrial natriuretic peptide (ANP) and fundamentally changed cardiology: the heart was not just a pump but a peptide-secreting gland that actively regulates blood pressure, fluid balance, and vascular tone. In the four decades since, researchers have identified an entire network of cardiovascular peptides, including BNP, endothelin, adrenomedullin, and apelin, each playing distinct roles in keeping the circulatory system functional. This network intersects with the broader gut peptide hormone signaling system through shared regulatory pathways and receptor families.
Understanding cardiovascular peptides matters because they are not just biological curiosities. BNP and NT-proBNP are now standard diagnostic biomarkers for heart failure. Sacubitril/valsartan, a drug that works by boosting natriuretic peptide levels, has become first-line therapy for heart failure with reduced ejection fraction. Endothelin receptor antagonists treat pulmonary arterial hypertension. The peptide biology is the medicine.
Key Takeaways
- ANP (28 amino acids) and BNP (32 amino acids) are released by heart muscle cells in response to wall stretch, promoting sodium excretion, vasodilation, and reduced blood volume (Kuwahara, Pharmacology and Therapeutics, 2021)
- BNP levels above 100 pg/mL have 90% sensitivity for diagnosing heart failure in emergency department patients with shortness of breath, per a joint ESC/AHA/JHFS scientific statement (Tsutsui et al., 2023)
- Adrenomedullin, a 52-amino-acid vasodilatory peptide discovered in 1993 from human pheochromocytoma tissue, produces long-lasting blood pressure reduction and protects vascular endothelial function (Kitamura et al., 1993)
- Apelin, acting through the APJ receptor, increases cardiac contractility without increasing oxygen demand, making it a promising target for heart failure therapy (Chandrasekaran et al., 2008)
- Sacubitril/valsartan combines neprilysin inhibition (boosting natriuretic peptides) with angiotensin receptor blockade, and its effects vary by baseline natriuretic peptide levels (Kondo et al., 2025)
- Endothelin-1, the most potent vasoconstrictor peptide known, is elevated in heart failure and drives pulmonary hypertension, making endothelin receptor antagonists a key drug class
The Natriuretic Peptide Family: ANP, BNP, and CNP
The natriuretic peptides are the heart's counterweight to the renin-angiotensin-aldosterone system (RAAS). Where RAAS raises blood pressure by retaining sodium and water, natriuretic peptides lower it by promoting sodium excretion (natriuresis), water excretion (diuresis), and vasodilation.
Atrial Natriuretic Peptide (ANP)
ANP is a 28-amino-acid peptide stored in granules within atrial cardiomyocytes. When the atrial wall stretches from increased blood volume, ANP is released into the circulation. It binds to natriuretic peptide receptor A (NPR-A) on target cells in the kidney, blood vessels, and adrenal glands, activating cyclic GMP signaling that promotes sodium excretion, inhibits renin and aldosterone secretion, and dilates blood vessels.[1]
The clinical significance of ANP extends beyond its immediate hemodynamic effects. Kuwahara's 2021 review described how ANP also suppresses cardiac fibrosis and hypertrophy, positioning it as a protective peptide against the structural remodeling that drives heart failure progression.[1]
B-Type Natriuretic Peptide (BNP)
BNP is a 32-amino-acid peptide synthesized primarily by ventricular cardiomyocytes. It was originally identified in porcine brain tissue (hence "brain natriuretic peptide"), but the ventricles are its main source in humans. BNP is synthesized as a 108-amino-acid prohormone (proBNP), which is cleaved into the biologically active BNP and the inactive N-terminal fragment (NT-proBNP). Both are released in equimolar amounts but have different half-lives: BNP circulates for about 20 minutes, while NT-proBNP persists for 60 to 120 minutes.[2]
This difference in half-life makes NT-proBNP plasma levels three to five times higher than BNP, which has practical implications for which assay clinicians choose. The 2023 joint scientific statement from the Heart Failure Association of the ESC, Heart Failure Society of America, and Japanese Heart Failure Society confirmed that both BNP and NT-proBNP are diagnostic and prognostic biomarkers for heart failure, with a BNP cutoff of 100 pg/mL having 90% sensitivity for detecting heart failure in dyspneic emergency department patients.[2]
C-Type Natriuretic Peptide (CNP)
CNP differs from ANP and BNP in that it is produced primarily by vascular endothelial cells rather than cardiomyocytes. It acts locally as a paracrine factor, promoting vasodilation and inhibiting vascular smooth muscle proliferation through natriuretic peptide receptor B (NPR-B). CNP plays a role in vascular homeostasis and has emerged as a potential therapeutic target for vascular remodeling diseases.[1]
Endothelin: The Vasoconstrictor Counterpart
Endothelin-1 (ET-1), discovered by Masashi Yanagisawa in 1988, is a 21-amino-acid peptide and the most potent endogenous vasoconstrictor known. It is produced primarily by vascular endothelial cells and acts on two receptor types: ETA (on vascular smooth muscle, mediating vasoconstriction) and ETB (on endothelial cells, mediating vasodilation through nitric oxide release, and on smooth muscle, mediating additional vasoconstriction).
In healthy circulation, endothelin works in balance with vasodilatory peptides like ANP and adrenomedullin. In disease states, this balance breaks down. Plasma endothelin-1 levels are elevated in heart failure, and the magnitude of elevation correlates with disease severity and prognosis.[1] Endothelin contributes to cardiac remodeling by promoting fibroblast proliferation and cardiomyocyte hypertrophy.
Endothelin receptor antagonists (bosentan, ambrisentan, macitentan) are now established therapy for pulmonary arterial hypertension, where ET-1 overproduction drives vascular remodeling and progressive right heart failure. Attempts to use ET receptor antagonists in systemic heart failure have been less successful, with clinical trials showing fluid retention as a limiting side effect.
Adrenomedullin: The Versatile Vasodilator
Adrenomedullin (AM) is a 52-amino-acid peptide first isolated from human pheochromocytoma (adrenal tumor) tissue by Kitamura et al. in 1993.[3] Despite its discovery in adrenal tissue, adrenomedullin is expressed widely across the cardiovascular system, lungs, kidneys, and brain. Intravenous administration produces long-lasting hypotension through direct vasodilation and suppression of aldosterone secretion.
Adrenomedullin has cardioprotective properties beyond vasodilation. It protects endothelial barrier function, suppresses oxidative stress, and inhibits excessive tissue proliferation. Plasma levels rise markedly during sepsis, where adrenomedullin appears to play a compensatory role in maintaining vascular tone. Levels also increase in proportion to heart failure severity, serving as both a biomarker and a functional compensatory mechanism.[3]
Mid-regional pro-adrenomedullin (MR-proADM), the stable precursor fragment, has emerged as a prognostic biomarker for heart failure and sepsis, as the active peptide itself is rapidly cleared from circulation.
Apelin: The Inotrope Without the Cost
Apelin is a peptide (existing in multiple active forms: apelin-13, apelin-17, and apelin-36) that acts through the APJ receptor, a G-protein coupled receptor expressed in the heart, blood vessels, kidneys, and brain. Chandrasekaran et al. reviewed the cardiovascular role of apelin in 2008, highlighting a property that makes it unique among cardiovascular peptides: it increases cardiac contractility (positive inotropy) without increasing myocardial oxygen consumption.[5]
In healthy hearts, apelin promotes vasodilation and increases cardiac output. In failing hearts, apelin levels drop, and APJ receptor expression decreases. This decline correlates with reduced cardiac performance, suggesting that the apelin system is part of the compensatory machinery that fails as heart failure progresses.[5]
The apelin-APJ axis also interacts with the RAAS: ACE2, the enzyme that converts angiotensin II to the vasodilatory angiotensin-(1-7), also cleaves apelin-13, creating a complex regulatory intersection between these two peptide systems. This has implications for understanding why ACE inhibitors and ARBs improve heart failure outcomes through mechanisms beyond angiotensin blockade alone.
The Renin-Angiotensin System: Peptides That Raise Blood Pressure
Angiotensin II, an 8-amino-acid peptide generated by the sequential action of renin and angiotensin-converting enzyme (ACE), is the primary effector of the RAAS. It causes potent vasoconstriction, stimulates aldosterone release (promoting sodium retention), promotes thirst, and triggers cardiac and vascular remodeling through AT1 receptor activation.
The RAAS and the natriuretic peptide system operate as opposing regulatory arms. When blood pressure drops, the RAAS activates to retain fluid and constrict vessels. When blood volume rises, natriuretic peptides activate to excrete fluid and dilate vessels. In heart failure, both systems become chronically activated, creating a pathological tug-of-war that drives disease progression.[1]
Adipokine signaling from fat tissue adds another layer to this regulation, as leptin and other fat-derived peptides influence sympathetic tone and RAAS activity, linking obesity to hypertension through peptide crosstalk.
Sacubitril/Valsartan: Harnessing the Natriuretic Peptide System
The therapeutic breakthrough of sacubitril/valsartan (brand name Entresto) directly exploits cardiovascular peptide biology. Sacubitril inhibits neprilysin, the enzyme that degrades natriuretic peptides, while valsartan blocks the angiotensin II type 1 receptor. The net effect is simultaneous boosting of the protective natriuretic peptide system and suppression of the harmful RAAS.[4]
Andersen et al. described the pharmacological rationale in 2016, noting that neprilysin inhibition alone could not be used because neprilysin also degrades angiotensin II; blocking neprilysin without also blocking angiotensin receptors would paradoxically increase angiotensin II levels.[4]
Nougue et al. confirmed the mechanistic basis in a 2019 clinical study, showing that sacubitril/valsartan increased circulating levels of ANP, BNP, and other neprilysin substrates in chronic heart failure patients, while NT-proBNP (which is not a neprilysin substrate) decreased, reflecting genuine improvement in cardiac wall stress rather than just enzyme inhibition.[7]
Most recently, Kondo et al. analyzed data from the PARADIGM-HF and PARAGON-HF trials in 2025, finding that sacubitril/valsartan's benefits varied by baseline natriuretic peptide levels, with greater treatment effects observed in patients with higher baseline NT-proBNP concentrations.[6] This finding has implications for personalizing heart failure therapy based on the patient's own peptide biomarker profile.
How These Peptides Work Together
The cardiovascular peptide network is not a collection of independent actors. It is an integrated system where each peptide's effect is modulated by the others:
ANP and BNP oppose angiotensin II and endothelin-1, creating a vasodilatory/natriuretic counterbalance to the vasoconstrictive/fluid-retaining RAAS. Adrenomedullin reinforces the natriuretic peptide arm while also providing unique endothelial protective effects. Apelin adds inotropic support without the oxygen cost of catecholamine stimulation. Endothelin-1, in healthy states, maintains vascular tone through its ETB-mediated nitric oxide release, but becomes pathological when overproduced.
When this network fails, as in heart failure, the balance tips toward vasoconstriction, fluid retention, and cardiac remodeling. Every major class of heart failure drug targets some component of this peptide network: ACE inhibitors and ARBs block angiotensin II production or action, neprilysin inhibitors boost natriuretic peptides, beta-blockers reduce sympathetic activation that drives RAAS, and mineralocorticoid receptor antagonists block aldosterone's downstream effects.[2]
The Bottom Line
Cardiovascular peptides form an integrated regulatory network centered on the balance between the protective natriuretic peptide system (ANP, BNP, CNP) and the pathogenic overactivation of the renin-angiotensin-aldosterone system and endothelin. Adrenomedullin and apelin provide additional vasodilatory and cardioprotective effects. BNP and NT-proBNP have become essential diagnostic biomarkers for heart failure, and sacubitril/valsartan represents the first drug class designed specifically to boost the natriuretic peptide arm of this network.