Effects of structural analogues of apelin‑12 in acute myocardial infarction in rats

Objective: To examine cardioprotective effects of С‑terminal fragment of adipokine apelin‑12 (A12), its novel structural analogue [MeArg1, NLe10]‑A12 (I), and [d‑Ala12]‑A12 (II), a putative antagonist of APJ receptor, employing in vivo model of ischemia/reperfusion (I/R) injury. Materials and Methods: Peptides were synthesized by the automatic solid phase method using Fmoc technology. Anesthetized open‑chest male Wistar rats were subjected to left anterior descending (LAD) coronary artery occlusion and coronary reperfusion. Hemodynamic variables and electrocardiogram (ECG) were monitored throughout the experiment. Myocardial injury was assessed by infarct size (IS), activity of necrosis markers in plasma, and metabolic state of the area at risk (AAR). Results: Intravenous injection of A12, I, or II at the onset of reperfusion led to a transient reduction of the mean arterial pressure. A12 or I administration decreased the percent ratio of IS/AAR by 40% and 30%, respectively, compared with control animals which received saline. Both peptides improved preservation of high‑energy phosphates, reduced lactate accumulation in the AAR, and lowered CK‑MB and LDH activities in plasma at the end of reperfusion compared with these indices in control. Treatment with II did not significantly affect either the IS/AAR, % ratio, or activities of both markers of necrosis compared with control. The overall metabolic protection of the AAR in the treated groups increased in the following rank: II <A12 <I. Conclusions: The structural analogue of apelin‑12 [MeArg1, NLe10]‑A12 may be a promising basis to create a new drug for the treatment of acute coronary syndrome.