Background: Metabolic and structural changes in cardiomyocytes in diabetes mellitus lead to aggravation of contractile myocardial dysfunction in coronary heart disease (CHD). The contractility dysfunction of cardiomyocytes is determined by a change in the levels of sarcoplasmic reticulum (SR) Ca2+-ATPase and energetic supply of the cardiomyocytes. Aims: To study the features of functional remodeling of the heart muscle in coronary heart disease with and without type 2 diabetes mellitus (DM2) depend on the level of Ca2+-ATPase and the activity of enzymes involved in energy metabolism. Materials and methods: The work was performed on the heart biopsy of patients with CHD and patients with CHD combined with DM2. The inotropic reaction of myocardial strips on rest periods was assessed. The expression level of Ca2+-ATPase, the activity of enzymes succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) and the intensity of oxidative phosphorylation processes were determined. Results: The interval-force relationship in patients with CHD with and without DM2 had both negative and positive dynamics. The positive dynamics corresponds to the "high content" of the Ca2+-ATPase and the negative dynamics corresponds to the "low content" were found. At the combined pathology the positive inotropic dynamics is more pronounced and corresponds to a higher protein level. In the patients myocardium with CHD the activity of SDH and LDH was higher, while the oxygen uptake rate by mitochondria was higher in the myocardium with combined pathology. Conclusions: The potentiation of inotropic response of patient myocardium with CHD with and without DM2 corresponds to the "high level" of Ca2+-ATPase. In the combined pathology the inotropic capabilities of the myocardium are more expressed. In CHD the synthesis of ATP in cardiomyocytes is realized mainly due to glycolytic processes and Krebs cycle. In combined pathology the ATP synthesis is realized to a greater extent due to the oxidative phosphorylation.

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BACKGROUND: Adequate glycemic control can significantly reduce the risk of developing cardiovascular events. However, until now, glycaemic targets in aged patients remain a subject of discussion, especially in the conditions of the combined development of Type 2 Diabetes Mellitus (T2DM) and ischemic heart disease (IHD).AIMS: To examine the structural and functional heart parameters in patients with IHD associated with T2DM and the rhythmoinotropic responses of their isolated myocardium depending on glycated hemoglobin level.MATERIALS AND METHODS: The study included 44 patients with a diagnosis of "chronic IHD associated with T2DM", of which 2 groups were formed. Patients with glycated hemoglobin level (HbA1c) <8% were included in the 1st group, and patients with HbA1c ≥8% were included in the 2nd group. The structural and functional heart parameters obtained with ultrasonography, and the rhythmoinotropic responses of myocardium in patients ex vivo were analyzed using the right atrial appendage fragments obtained during elective coronary artery bypass graft. The inotropic response of muscle strips at a basic stimulation frequency of 0,5 Hz to testing influences was assessed. An extrasystolic test and post-rest test were performed.RESULTS: It was found that extrasystolic contractions of isolated myocardial strips in patients of the 2nd group appeared at shorter extrasystolic intervals, which indicates a greater excitability of the myocardium in patients of this group. Postextrasystolic muscle contractions in patients of the 2nd group had significant potentiation. The amplitude of the muscle strips contractions in patients of both groups was potentiative after short rest periods. However, with an increase in the rest duration, potentiation of contractions was observed only in the group with a higher HbA1c level. According to the ultrasonography data, it was found that the values of the endsystolic and diastolic volumes, the interventricular septum thickness and the left ventricular (LV) myocardium mass were significantly lower in the patients of the 1st group compared with the corresponding indicators in the patients of the 2nd group. The early LV filling velocity (peak E) was significantly lower in the patients of the 1st group, which indicates a slower LV relaxation. At the same time, the rapid LV filling velocity did not have a significant intergroup difference, but this indicator exceeded the reference values in both groups.CONCLUSIONS: With a moderately increased glycemic level (9,2 [8,0; 10,3]%), the structural and functional heart parameters are preserved both at the level of the isolated myocardial tissue and at the level of the whole heart.