reviewed april 2026|next review october 2026|88 physicians psi has verified|17282 published studies
Apelin
Apelin is a naturally occurring (the body's own) peptide that activates the APJ/APLNR receptor, functioning as a counter-regulatory cardiovascular signal that promotes vasodilation, strengthens cardiac output, and enhances glucose utilization, with early human hemodynamic data in heart failure patients.
Evidence landscape: 17282 published studies
Published studies indexed under this compound. The broader apelin/APJ receptor literature encompasses several hundred papers across cardiovascular, metabolic, and fluid balance research.
- 15 Human
- 137 Animal
- 48 Reviews
- 17082 Other research
Not FDA-approved. No apelin-based drug has reached regulatory approval. Modified apelin analogs are in early clinical development for heart failure and pulmonary hypertension.
Not commercially available as a therapeutic. Naturally occurring (the body's own) peptide with an extremely short half-life (seconds to minutes) that prevents direct therapeutic use. Stable analogs are in development.
Apelin is the naturally occurring (the body's own) ligand for the APJ receptor (also called APLNR), which was originally identified as an angiotensin-related receptor but signals through an independent pathway. The apelin system is one of several counter-regulatory cardiovascular peptide systems alongside angiotensin 1-7 and natriuretic peptides.
PSI Assessment
When researchers infused apelin into heart failure patients, cardiac output increased and vascular resistance dropped without raising heart rate. That hemodynamic profile is notable because most positive inotropes (agents that strengthen heart contractions) carry the trade-off of increased oxygen demand and arrhythmia risk. Apelin appears to strengthen the heart while simultaneously reducing the workload it faces. The challenge is that native apelin degrades in seconds, making direct therapeutic use impractical without modified analogs.
Positive inotrope without increased oxygen demand. Human heart failure hemodynamic data. Native peptide degrades in seconds, requiring analog development for therapeutic use.
The mechanism is APJ/APLNR receptor activation, a Gi-coupled GPCR (G-protein coupled receptor). When apelin binds this receptor, it triggers vasodilation through nitric oxide-dependent and nitric oxide-independent pathways, positive inotropy (increased contractile force) without hypertrophy, and enhanced glucose utilization through AMPK (AMP-activated protein kinase) activation. The system operates as a counter-regulatory arm alongside angiotensin 1-7 and natriuretic peptides.
What the evidence supports
Apelin infusion produces measurable hemodynamic improvement in heart failure patients, including vasodilation and increased cardiac output. The APJ/APLNR receptor system is well characterized across multiple laboratories. Apelin levels are altered in cardiovascular disease states, supporting biological relevance beyond pharmacological observation.
What is not yet established
Whether stable apelin analogs can overcome the native peptide's extremely short half-life to become viable drugs. Long-term cardiovascular outcomes from apelin-based interventions. Whether the hemodynamic effects observed in acute infusion studies translate to chronic disease modification.
Research Evidence
The findings below cover what human infusion studies and animal research have established about apelin's cardiovascular biology and the obstacles to therapeutic development.
Evidence by condition
Evidence dimensions across apelin's investigated applications. Heart failure has the strongest translational signal with human hemodynamic data. Pulmonary hypertension and metabolic applications remain primarily in animal models (animal research).
| Condition | Mechanism | Animal evidence | Human evidence | Replication |
|---|---|---|---|---|
| Heart Failure | ||||
| Pulmonary Hypertension | ||||
| Metabolic Regulation | ||||
| Fluid Balance |
Apelin infusion in human heart failure patients produced vasodilation and increased cardiac output without raising heart rate. The hemodynamic profile showed reduced systemic vascular resistance with maintained or improved blood pressure.
These effects were observed in acute infusion studies. Whether sustained apelin receptor agonism produces similar benefits in chronic heart failure is not established. The very short half-life of native apelin limits the duration of effect.
Apelin acts as a positive inotrope that increases the force of cardiac contraction without increasing myocardial hypertrophy or oxygen demand. This distinguishes it from most existing inotropic agents.
The positive inotropic effect was first demonstrated in isolated rat hearts and subsequently confirmed in human hemodynamic studies. The mechanism involves phospholipase C and protein kinase C signaling rather than the beta-adrenergic pathway used by conventional inotropes.
Reduced apelin signaling is associated with pulmonary arterial hypertension in animal models. Apelin knockout mice develop pulmonary hypertension, and apelin administration reduces pulmonary vascular resistance.
Human observational data shows altered apelin levels in cardiovascular disease states. Whether restoring apelin signaling can reverse established pulmonary hypertension in humans is not yet tested.
15 Human|137 Animal|48 Reviews
View all 17282 indexed studiesHow Apelin Works
Apelin tells blood vessels to relax and the heart to pump more strongly. When apelin activates its receptor (APJ), blood vessels widen, the heart contracts with more force without working harder, and the body uses glucose more efficiently. It functions like a counter-regulatory signal that balances the harmful effects of excessive angiotensin II activity.
Apelin tells blood vessels to relax and the heart to pump more efficiently. When apelin activates its receptor (APJ), blood vessels widen, the heart contracts more strongly, and the body uses glucose more effectively.
For a more detailed view of the biology, here is what researchers have observed at the molecular level.
Apelin activates the APJ/APLNR receptor, a Gi-coupled GPCR, promoting vasodilation through nitric oxide-dependent and nitric oxide-independent mechanisms. In cardiomyocytes, apelin produces positive inotropic effects via PLC/PKC (phospholipase C/protein kinase C) signaling without activating hypertrophic pathways. It enhances glucose utilization via AMPK activation in skeletal muscle and adipose tissue. Active isoforms include apelin-13, apelin-17, and apelin-36, with apelin-13 being the most potent. Native peptide half-life is seconds to minutes due to rapid degradation by ACE2 and other peptidases.
What is Apelin being studied for?
Researchers are studying Apelin across several health conditions. Each condition below is labeled with the strength of evidence that exists for that specific use, not for Apelin overall. This means a compound can have human studies for one condition but only animal data for another.
Heart Failure
·Human TrialsHuman infusion studies demonstrate that apelin improves cardiac output and reduces vascular resistance in heart failure patients. The hemodynamic profile is favorable compared to conventional inotropes.
Limitations: Acute infusion data only. No chronic administration studies in humans. Native apelin's extremely short half-life prevents direct therapeutic use. Modified analogs are in early clinical development.
Pulmonary Hypertension
·Animal StudiesApelin is a vasodilator in the pulmonary circulation. Reduced apelin signaling is associated with pulmonary arterial hypertension in animal models (animal research). Apelin knockout mice develop the condition.
Limitations: Human pulmonary hypertension data is limited to observational associations. No interventional human studies for this indication.
Metabolic Regulation
·Animal StudiesApelin enhances glucose utilization and has insulin-sensitizing effects through AMPK activation in animal models (animal research).
Limitations: Metabolic applications are entirely in animal models. No human metabolic intervention data.
Fluid Balance
·Animal StudiesApelin modulates water intake through hypothalamic signaling and interacts with the vasopressin system in fluid homeostasis.
Limitations: Fluid balance effects characterized in animal models. Clinical relevance of apelin-mediated fluid regulation is not established.
Safety and Regulatory Status
FDA Status: Not FDA-approved. No apelin-based drug has reached regulatory approval. Modified apelin analogs are in early-stage clinical development.
Availability: Not commercially available as a therapeutic. Naturally occurring (the body's own) peptide. The extremely short half-life prevents direct therapeutic use.
Class context: Apelin is naturally occurring with a favorable theoretical safety profile. Human infusion studies have shown good tolerability with no significant adverse effects reported during acute administration. The primary limitation is pharmacokinetic, not toxicological.
Apelin is naturally occurring (the body's own) and has been well tolerated in human infusion studies. No significant safety concerns have been identified from acute administration. Modified analogs in clinical development will require their own safety evaluation. The primary barrier to therapeutic use is the extremely short half-life, not safety.
Questions and Comparisons
Questions the evidence raises for a Apelin discussion.
Comparison and Related Research
Apelin is most often compared with other counter-regulatory cardiovascular peptides that oppose the harmful effects of excessive angiotensin II activity.
Related compounds
Frequently Asked Questions
References
Each citation links to the original study on PubMed, the U.S. National Library of Medicine database.
- 1.The original discovery paper for apelin. Researchers isolated this peptide from bovine stomach extracts and identified it as the endogenous ligand for the previously orphan APJ receptor. This foundational work launched the entire field of apelin research in cardiovascular and metabolic biology.Tatemoto K et al., 1998 in Biochem Biophys Res Commun. View on PubMed
- 2.Demonstrated that apelin directly increases the force of heart muscle contractions. Working with isolated rat hearts, the study showed apelin produced a potent positive inotropic effect mediated through phospholipase C and protein kinase C signaling. This was the first evidence that the apelin system plays a direct role in cardiac function.Szokodi I et al., 2002 in Circ Res. View on PubMed
- 3.First study to infuse apelin directly into healthy human volunteers and patients with heart failure. Apelin caused peripheral vasodilation and increased cardiac output without raising heart rate. In heart failure patients, apelin improved cardiac function, suggesting therapeutic potential for this population.Japp AG et al., 2008 in Circulation. View on PubMed
- 4.Measured apelin blood levels in heart failure patients and healthy controls. Patients with chronic heart failure had significantly lower circulating apelin concentrations, and levels correlated with disease severity. This established apelin as a potential biomarker for cardiac dysfunction.Chong KS et al., 2006 in Eur J Heart Fail. View on PubMed
- 5.Comprehensive review covering the role of the apelin/APJ system in glucose metabolism, insulin sensitivity, and adipose tissue function. The paper summarized evidence that apelin improves glucose uptake in muscle, reduces adipose tissue inflammation, and may represent a therapeutic target for metabolic disease.Castan-Laurell I et al., 2011 in Endocr Rev. View on PubMed
Medical Disclaimer
This content is for educational and informational purposes only and does not constitute medical advice. The information presented reflects published research as indexed by PSI and should not be used to make treatment decisions. Always consult a qualified healthcare provider before starting, stopping, or modifying any treatment.