Apelin, an endogenous ligand for the G-protein-coupled APJ receptor, has been recently extensively studied in obesity research. It is not only expressed in adipocyte tissue, but also widely expressed in various other organs such as the heart, lung, kidney, gastrointestinal tract, brain, adrenal glands, endothelium, and human plasma.Apelin is derived from a 77-amino-acid prepropeptide that is cleaved into a 55-amino-acid fragment and then into shorter forms. The physiologically active form is thought to be apelin 36, although the pyroglutamylated form of apelin 13, which is also produced endogenously, is more potent.Studies have shown the association between apelin and obesity. Apelin has higher circulating levels in obesity. Insulin exerts a positive action on adipocyte apelin production. Apelin also regulates fluid homeostasis, playing an important role in the hypothalamic regulation of food and water intake, and pituitary hormone release.In addition to its role in obesity, apelin acts as a mediator of cardiovascular control, including for blood pressure and blood flow. It is one of the most potent stimulators of cardiac contractility yet identified, and plays a role in cardiac tissue remodeling. Apelin levels are increased in left ventricles of patients with chronic heart failure and also in patients with chronic liver disease.

Standard, Biotinylated Apelin C-Terminus peptide, and Positive Control should be stored at -20°C after arrival. Avoid multiple freeze-thaws. The remaining kit components may be stored at 4°C. Opened Microplate Wells and antibody (Item N) may be stored for up to 1 month at 2° to 8°C. Return unused wells to the pouch containing desiccant pack and reseal along entire edge.