Age characteristics of myocardial blood supply in comorbid pathology

Abstract

Understanding the age-related changes in myocardial blood supply under conditions of diabetes mellitus and stress will help reveal the pathway of diabetic cardiomyopathy, considering the age aspect. Therefore, the aim of our work is to investigate the age-related morpho-functional changes in the hemomicrocirculatory bed (HMB) of the myocardium in rats with experimental streptozotocin-induced diabetes mellitus (SDM) under conditions of chronic immobilization stress (CIS). The study used heart fragments and blood from 56 2-month-old and 6-month-old male white rats, which were divided into 3 groups: 1 group with comorbid pathology, including modeled SDM and CIS, 2 group with SDM, and 3 – control group. The material was collected 14th and 56th days from the start of the experiment. According to our findings, hyperglycemia, and stress on the 14th day of the experiment lead to spasm of the arterioles of the HMB and a significant deterioration in their permeability, as evidenced by a likely increase in the Vongenwort index in the arterioles. On the 56th days, in the experimental groups of 6-month-old rats, vacuolar dystrophy and coagulation necrosis of endotheliocytes and myocytes, focal destruction of capillary walls, thickening, and proliferation of their basement membrane, pronounced micro- and macroclasmatic changes, and capillarosclerosis are observed. In contrast, 2-month-old rats alongside destructive changes in HMB vessels show phenomena of neovascularization. Thus, SCD leads to the development of diabetic microangiopathy in the vessels of the myocardium of rats of different age groups. In animals with comorbid pathology, damage of HMB vessels are more pronounced on the 56th day of observation and is manifested by: destruction of capillary walls, capillarosclerosis. In 2-month-old rats, alongside destructively changed capillaries, we found to former new vessels with a characteristic ultrastructure. Keywords: heart, heart failure, diabetic cardiomyopathy, diabetes mellitus, cardiovascular diseases, hemomicrocirculatory bed.