Not only the prevalence, but also the death rate from the coronary heart disease, including myocardial infarction, is higher in older people than among young people. A demographic shift towards an aging population will lead to a further increase in the prevalence of cardiovascular diseases among the elderly population. Therefore, one of the urgent aims of modern experimental and clinical medicine is to develop methods aimed at limiting reversible and irreversible damage to the myocardium, including in elderly patients. There are a lot of the data supporting the cardioprotective efficiency of such phenomena as ischemic and pharmacological pre- and postconditioning that reduce ischemic and reperfusion damage in young hearts. However, the information on the effectiveness of these phenomena in experiments on old animals is very scarce, contradictory, and not fully understood. The aim of the study was to experimentally evaluate the influence of old age on the reproducibility of the cardioprotective efficiency of pharmacological postconditioning using lactic acid in ischemia-reperfusion of the myocardium. In the course of the study, it was found that neutral lactate, after being administered into the blood flow of animals at a dose of 10 mg/kg 25 minutes after the onset of reperfusion, leads to a decrease in the infarct size of the left ventricle of the myocardium in old rats. Pharmacological postconditioning using lactate is not effective in reducing the duration of cardiac arrhythmias in ischemia-reperfusion of the myocardium in old rats; however, there is a tendency to reduce the incidence of reperfusion arrhythmias and the total duration of cardiac arrhythmias. The obtained data suggest that the presence of such a risk factor for cardiovascular diseases as old age is not a criterion to exclude the use of pharmacological postconditioning with lactate as a way to reduce ischemia and reperfusion injury of myocardium.

Taking into account the high medical and social significance of the problem of treating patients with coronary heart disease and acute myocardial infarction, the search for new effective methods of preventing or weakening ischemic and reperfusion myocardial damage and finding out the mechanisms of their implementation is an urgent task of modern experimental and clinical medicine. The aim of the study was to conduct a comparative analysis and clarification of features of the cardioprotective efficiency of postconditioning with lactate in ischemia-reperfusion of the myocardium in young and old rats and rats with transient hypercholesterolemia (HCE). It was found that remote ischemic postconditioning (RIPostC) in ischemia-reperfusion of the myocardium has an infarction-limiting effect and is accompanied by an increase in the level of lactate in the blood, and lactate after injection into the bloodstream of animals at a dose of 10 mg/kg 25 min after the start of reperfusion leads to a decrease in the size of the necrosis zone in the left ventricular myocardium in young and old rats. However, postconditioning with lactate is not effective in limiting the size of the zone of necrosis in the left ventricular of myocardium in young and old rats with transient HCE. There is reason to suppose that hyperlactatemia takes part in the realization of the cardioprotective effect of RIPostC. The presence of such a risk factor for cardiovascular diseases as HCE can serve as a criterion for excluding the use of postconditioning with lactate as a way to reduce ischemic and reperfusion damage to the myocardium in patients with acute myocardial infarction.

When conducting electrophysiological studies, electrodes are used to register bioelectrical signals, the correct choice and use of which determine the reliability and diagnostic significance of the data obtained. Recording an electrocardiogram is a standard procedure in medicine, but its monitoring is often limited to 24 hours.This is due to the limited performance of the electrodes. The properties of the skin/electrode interface determine the performance of medical equipment. Therefore, the surface conditions and the composition of the material from which the electrode is made should comply with the requirements of the electrocardiogram recording device. It is important to implement fast transmission of a useful signal with low losses and without artifacts. Modern electrodes using Ag/AgCl have a limited-service life, since their dehydration and surface degradation lead to the formation of various artifacts on the electrocardiogram record. Alternative – dry flexible electrodes. Such electrodes can be based on carbon materials (reduced graphene oxide or a diamond-like coating) on a plastic (film) substrate. The emphasis of modern research is aimed at carrying out work on the development of dry electrodes, which would provide an opportunity to carry out high-quality long-term registration of electrocardiosignals without gels and adhesives.

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