Apelin is an endogenous peptide ligand for the APJ receptor (APLNR), existing in multiple bioactive forms including apelin-13, apelin-17, and apelin-36 derived from a 77-amino-acid preproapelin precursor. It plays important roles in cardiovascular regulation, fluid homeostasis, and cardiac inotropy. All forms remain in preclinical or early clinical investigation with no approved therapeutic applications.
Category: Cardiovascular / Vasoactive. Evidence rating: D (animal/preclinical only).
Clinical status: Preclinical and early-phase clinical investigation. No approved therapeutic indication.
Apelin binds to the APJ receptor (APLNR), a Gi-coupled GPCR. In the cardiovascular system, apelin/APJ signaling produces positive inotropy via phospholipase C activation and increased intracellular calcium in cardiomyocytes, independent of cAMP. It causes NO-dependent vasodilation in the…
Safety considerations: No human safety data from controlled clinical trials; Hypotension is the expected pharmacological effect and primary theoretical risk; Potential effects on fluid balance due to vasopressin antagonism.
Reviewed by the PeptideAtlas Editorial Team.
| Half-life | <5 minutes (circulating) |
|---|---|
| Production method | synthetic |
| Anti-doping status | not-listed |
| US regulatory status | Not approved. Research compound only. |
Related peptides: Angiotensin II, Angiotensin 1-7, Bradykinin.
Apelin exists in multiple forms derived from the 77-AA preproapelin precursor: apelin-36 (C-terminal 36 AA), apelin-17, and apelin-13. [Pyr1]apelin-13 (with N-terminal pyroglutamate) is the most abundant and potent endogenous form. All forms bind the same APJ receptor but with varying affinities and pharmacokinetics.
Apelin is a positive inotrope that does not increase myocardial oxygen demand, unlike catecholamines. Plasma apelin levels are reduced in heart failure, suggesting a relative deficiency. Restoring apelin signaling could theoretically improve cardiac output without the adverse effects of catecholamine-based inotropes. However, this remains unproven in clinical trials.
Apelin is expressed in adipose tissue and may play a role in insulin sensitivity and glucose metabolism. Some studies show altered apelin levels in type 2 diabetes and obesity, but the clinical significance is not established.