MORPHOFUNCTIONAL CHANGES OF THE MYOENDOCRINE ATRIAL CELLS AT POSTRESECTION PORTAL HYPERTENSION

Abstract

In recent years, the number of scientific works devoted to endocrine function of the heart has been increasing in the biomedical literature. It is known that in some atrial cells secretory granules are found that contain atrial natriuretic hormone. Most researchers named these specialized cardiomyocytes as myoendocrine cells in the atria or myoendocrine cardiomyocytes. It is also known that myoendocrine atrial cardiomyocytes respond promptly and pronouncedly to changes in the internal and external environment, providing the necessary stable level of physiological and biochemical processes in the body. Morphological aspects of the state of the endocrine apparatus of the heart have been studied in various physiologica and pathological conditions. At the same time, the features of secretory activity of atrial cardiomyocytes at postresection portal hypertension were not investigated. The purpose of the research – morphological study of peculiarities of changes of atrial myendocrine cells under conditions at postresection portal hypertension. Object and methods. A complex of morphological methods investigated myoendocrine cells of the atria of 45 laboratory adult white male rats, which were divided into 3 groups. The group 1consisted of 15 intact animals that were in normal vivarium conditions, 2-15 rats after resection of the left lateral lobe – 31.5% of the liver parenchyma, 3-15 animals after resection of the right and left lateral lobes of the liver (58,1%). Euthanasia of experimental animals was performed by bloodletting in codition of thiopental anesthesia 1 month after the beginning of the experiment. The relative volumes of secretory granules of the left and right of the atria and the percentages of young, mature and diffusing secretory granules were determined stereometrically on the electronograms. Quantitative indicators were processed statistically. Results and discussion. Resection of 58.1% of the liver parenchyma led to the development of postresection portal hypertension and changes the secretory activity of myoendocrine atrial cells. Thus, the relative volume of secretory granules in the left atrium with postresection portal hypertension decreased statistically (p <0.001) by 15.5%. A similar right atrial morphometric parameter was also reduced by 12.2% (p <0.001). In conditions of postresection portal hypertension expressed altered, the quantitative characteristics of young, mature and diffusing secretory granules were also revealed. The percentage of young secretory granules in the left atrium with a pronounced statistically significant difference (p <0.001) decreased by 5.5%, and the percentage of mature secretory granules by 8.1% (p <0.001). In the right atrium, the morphometric parameters studied were, respectively, reduced by 5.1 and 6.6% (p <0.001). The number of diffusing secretory granules in the left and right atrial myoendocrine cells under conditions of postresection portal hypertension increased markedly. Thus, the morphometric parameter in the left atrium was statistically significantly (p <0.001) increased by 13.5%, and in right – by 11.7% (p <0.001). Conclusion. Postresection portal hypertension changes the secretory activity of myoendocrine cells of the atria, which is characterized by a decrease in the relative volumes of secretory granules, impaired relationships between their types, an increase in the number of diffusing granules. More pronounced changes studied structures dominate in the left atrium.

Keywords

• postresection portal hypertension
• myoendocrine atrial cells.