[The role of apelin in pathogenesis of cardiovascular diseases and metabolic disorders].

Apelin is a recently discovered biologically active peptide present in several isoforms that are agonists for orphan receptor APJ. Apelin and APJ receptor were found in the central nervous system and in different peripheral tissues. In the cardiovascular system the peptide is present both in the heart and in the endothelium and smooth muscles cells of the vascular wall. Acting on cardiomyocytes apelin exerts positive inotropic effect, in the endothelium it releases nitric oxide, which mediates its vasodilatory action, while acting directly on smooth muscles cells it causes vasoconstriction. Apelin interacts with other compounds regulating blood pressure; for instance with angiotensin II, vasopressin, and with the sympathetic nervous system. Special attention is focused on the possibility of positive role of apelin in hypertension, initial stages of heart failure and ischaemic heart disease. Synthesis of apelin in adipocytes permits to include this peptide among adipokines. In the adipose tissue its production is increased in obesity and by insulin. It appears that apelin may play essential role in pathogenesis of insulin-resistant obesity. In patients with type 2 diabetes apelin improves glucose tolerance in initial stages of the illness. However, further experimental and clinical studies are required for full evaluation of significance of positive and negative aspects of the role of apelin in the cardiovascular and metabolic diseases.