Analytical and quantitative assessment of the condition of the heart wall of rats exposed to the venom of the vipers Vipera berus berus and Vipera berus nikolskii

Background. A significant number of factors of both physical and chemical origin can have a negative impact on the organs of the cardiovascular system. At the same time, implementing the damaging effect of factors of various genesis consists not only of changes in the normal functioning of the heart but also in the launch of complex pathogenetic mechanisms that cause pronounced structural changes in the organ, which are sometimes irreversible. Objective. The aim of the study is an analytical and quantitative assessment of the heart wall of rats exposed to the venom of the vipers Vipera berus berus and Vipera berus nikolskii. Methods. Experimental studies were conducted on white nonlinear male rats. The animals were conditionally divided into control and experimental groups, ten individuals each. Experimental rats were intraperitoneally administered a semi-lethal dose (LD50) (1.576 mg· g-1) of the venom of Vipera berus berus and Vipera berus nikolskii in saline. The animals of the control group were intraperitoneally injected with saline only. Rats were removed from the experiment 24 hours after exposure to the poison and anaesthetised by cervical dislocation. Heart samples were taken for microscopic examination. Material fixation and preparation of paraffin blocks were carried out according to generally accepted methods. Histological preparations of the heart were stained with Picro Sirius Red/Fast Green and hematoxylin-eosin. For a detailed assessment of the effect of the venom of two species of vipers on the general condition of the rat heart, we compared absolute and relative variables, which were measured and calculated, respectively, using Fiji: ImageJ program, between the control and both experimental groups exposed to the venom of the vipers Vipera berus berus and Vipera berus nikolskii. Statistical processing was carried out using the Excel program with subsequent construction of graphs to visualise the results obtained. Results and conclusion. According to the data of morphometric studies, a more pronounced harmful effect of the venom of Vipera berus nikolskii was established, which was manifested in the violation of the structure and shape, oedema of cardiomyocytes, which led to significantly higher indicators of the width of these cells both in comparison with the control group and with the second experimental group. In addition, the action of both venoms, albeit to different degrees, led to the growth of connective tissue elements within the endomysium, which was reflected in an increase in the indicator of the proportion of this tissue in the myocardium. The venoms of both vipers provoked an increase in the proportion of connective tissue in the myocardium; however, against the background of oedema of muscle cells, the relative increase in the area of ​​endomysium to them shows a tendency to increase but is not reliable.