STRUCTURAL CHANGES OF ENDOTHELIUM OF LEFT VENTRICLE ENDOCARDIUM IN RATS IN POST-STRESS PERIOD

The purpose of the research was to study the structural changes of endothelial cells in the left ventricular endocardium of rats under the influence of acute three-hour emotional-pain stress, in particular in the post-stress period. An electric pulse model was used for stress repro-duction. The endothelium of the endocardium was studied with the help of light optic microscopy, analyzing smears-imprints by number of mutilated cells per 1 mm² of the area of the imprint. Smears-imprints were prepared from the macro-preparations of the left ventricle, applying them to the objective glasses. Also, changes of the endothelial cells nuclei were studied. Structural changes of the endocardium endothelium were analyzed immediately after a three-hour stress, also in the post-stress period - 6 and 24 hours after the stressor's action. It was established that the result of the acute three-hour emotional-pain stress is the damage of endocardium, which is accompanied by desquamation of separate endothelial cells. The number of desquamated cells in micro-preparations has increased in 2.1 times in comparison with the control. Single placement of cells in the field of vision is predominant in smears-imprints, much less the accumulations of 5-10 endothelial cells are seen. The degree of the damage of the endocardium endothelium increases significantly in the post-stress period. Especially this phenomenon is obvious after 24 hours after stress influence. Under these conditions the number of desquamated cells in smears-imprints increases in 4.5 times compared with the control group of animals and in 2.2 times in comparison with the same index, that was determined immediately after the stress influence. In this period, endothelial cells are often desquamated into layers (5-20 cells). In addition to enhancing of the process of endothelial cells desquamation of endo-cardium under conditions of stress reaction we found morphometric indices of changes in their nuclei. In particular, 24 hours after the acute emotional-pain stress in the endothelium of the endocardium, there is a statistically significant increase in the number of nuclei with signs of hyper-chromicity, kariopicnosis and karyolysis. Also, there is a change in the shape of the nuclei. So, under conditions of acute three-hour emotional-pain stress there is damage of endothelial cells of the left ventricular endocardium and their des-quamation, which manifests itself as much as possible in the post-stress period. This probably is connected with the sharp activation of the sympathoadrenal system and the multiple increase of catecholamine concentration in the blood that has pathoendotheliotropic effect. The fact that the expressed endothelium damage does not occur immediately after the action of the stressor, but in the post-stress period (after 6 and 24 h) can be explained in the following way. During the action of the stressor reversible changes in the endothelial cells appear that gradually increase with the occurrence of violations of the joints between endothelial cells and connection with the basal membrane, which eventually leads to the desquamation of the cells. As some scientists suggest, endothelial cells are susceptible to a number of other mechanisms: calcium, electrolyte-osmotic, acidophilic, which are activated by the nervous-humoral component of stress. In addition, within a day after acute stressful effect in the endothelium of the left ventricular endocardium, there are changes that indicate an increase of destructive processes and are a sign of adaptation of these cells to the influence of pathogenic factor. The results of further studies of the influence of stressors on the structure of the endothelium of the vessels in different organs will facilitate the disclosure of new links of pathogenesis of endothelial dysfunction in case of many diseases and the search for new approaches to their treatment.