Morphological illustration of alterations in the arterial endothelium in ischemic and reperfusion injuries

Abstract

Background. Reperfusion syndrome is an inevitable event in recovery of the blood flow after a longstanding ischemia. The article is dedicated to the study of the expressiveness of this condition.
 Aim – to compare the depth of morphological alterations of the arterial endothelium in ischemic and reperfusion injury in experiment.
 Materials and Мethods. The work was conducted on 90 laboratory animals – rats of Wistar line. Models of ischemia and reperfusion were obtained by compression of the abdominal part of the aorta (1st group) with further conditioning (2nd group). The animals were withdrawn from the experiment and the vessel wall was taken on the 1st, 3d, 5th, 7th day. Preparations were studied in a transmission electron microscope «Libra 120» with automatic scanning of images. 
 Results. Comparison of pathomorphological data obtained in examination of the aortas and iliac arteries of the two groups of animals («ischemia» and «reperfusion») showed that the cascade of pathomorphological changes includes several main stages. Transient ischemia leads to injury (alteration) of the main components of the vessel wall. Under action of this factor endotheliocytes exhibit a nonspecific response changing their synthetic activity that was manifested by a complex of morphological signs in the nucleus, karyolemma, cytoplasm and plasmalemma. In some cells the changes took an irreversible character and were accompanied by rupture of mitochondrial membranes, of general purpose organelles and of plasmalemma. Such endotheliocytes died and were desquamated. Because of short duration of ischemia these changes were insignificant. Subendothelial structures underwent edema which is logical in view of derangement of the barrier function of the epithelium and presence of a mild inflammatory component (in response to death of a part of endotheliocytes and cells of the vascular wall stroma). Examination of the ultrastructure of the vessel wall in the ischemiareperfusion group revealed adaptive and pathological changes in the endothelial cells. Data were obtained that evidence a significant disorder in microhemodynamics in tissues in reperfusion.
 Conclusion. No significant structural and ultrastructural differences in injuries and reactive changes in «ischemia» and «reperfusion» groups were found. In view of this, for subtle differentiation of pathomorphogenesis of these two conditions it is reasonable to use examination methods with higher resolution.