A.B. Berdalin, A.V. Golubeva, S.A. Gavrilova, S.V. Buravkov, V.P. Chernikov, V.B. Koshelev

Peptide drug Semax (ACTH fragment), according to our earlier study has a beneficial effect on myocardial remodeling and improves myocardial function in rats with irreversible left coronary ar-tery ligation and in a model with reperfusion, with no effect on the size of necrosis. Besides the drug reduces apoptotic cell death identified by TUNEL-analysis, particularly in relatively intact myocardium, with no effect on the severity of ischemic injury and the intensity of the inflammatory response. The aim of this work was to assess the impact of Semax at irreversible ischemia and ischemia-reperfusion on cardiac structure in the risk zone and the intact myocardium on the ul-trastructural level, focused on energy and the contractile apparatus of cells. 5 groups of male rats were investigated: control group; irreversible ischemia with drug and without; the animals with reperfusion after 2.5 hours of ischemia with drug and without it. Sam-ples for electron microscopy of the risk area (anterior wall of left ventricle) and conditionally intact myocardium (lateral wall and interventricular septum) were taken 72 hours after intervention. Semax were injected intraperitoneally at a dose of 150 mg / kg after 15 minutes and after 2 hours 15 minutes after ligation of coronary artery. Counting of intermitochondrial contacts (IMC) per 100 mitochondrias and evaluating of relative area of mitochondrias and myofibrils were performed. There was no influence of Semax on ultrastructure of cardiomyocites and relative density of mitochondria in all zones of heart as in irreversible ischemia and ischemia-reperfusion. However Semax reduced the number of IMC cardiomyocytes during ischemia and ischemia-reperfusion, which is probably associated with a decrease of myocardial energy requirements.