Apelin-13 TFA is an endogenous ligand for the G-protein coupled receptor angiotensin II protein J (APJ), activating this G protein-coupled receptor with an EC 50 value of 0.37 nM. Apelin-13 TFA has vasodilatory and antihypertensive effects. Apelin-13 TFA also can be used for researching type 2 diabetes and metabolic syndrome.