DISTURBANCES IN THE ENZYMATIC SYSTEMS IN LIVER PATHOLOGY

Аннотация

Changes in the activity of hepatic cell (hepatocyte) enzyme systems are at a stage of development or not fully studied. Among the recent findings is the fact that possible qualitative changes inthecatalytic activity ofenzymes occur when exposed tohepatotropic toxins. Key words:membrane, enzyme, mitochondria, monoamineoxidase, organelle, liver, cell, lipid. At the present stage of studying the pathogenesis of liver diseases, a significant focus is on the research of pathological processes at the level of subcellular structures, their membrane and enzymatic systems. Many works are being conducted in this direction, which provide detailed information on the mechanism of action of pathogenic agents and clarify the localization of the primary siteofcellular damage. In this regard, special interest lies in the study of the metabolism of biogenic amines and other nitrogenous compounds, in terms of the catalytic properties of mitochondrial monoamine oxidases. On one hand, these enzymes are involved in the metabolism of a number of biologically active nitrogenous compounds, and on the other hand, they are enzymes of organelles, the early damage of which has been established in a number of pathological processes in theliver. In experiments with highly purified monoamine oxidases, it was found that partial oxidation of the thiol groups of these enzymes not only reduces monoamine oxidase activity but also causes a qualitative change ("transformation") in the catalytic properties of monoamine oxidases, with the appearance ofthe abilityto deaminate nitrogenous compounds. Data obtained in experiments using selective inhibitors of different types of monoamine oxidases led to the conclusion that the transformation process involves type A monoamine oxidases, which are blocked by low concentrations of chlorline, rather than type B monoamine oxidases, for which deprenyl is aselective inhibitor. It turned out that theproperty of monoamine oxidase type A to undergo qualitative changes in catalytic activity is also realized in the whole organism under conditions of stimulated radical oxidative processes, particularly in the stimulation oflipidperoxidation. Apart from isolated works indicating the transformation of the catalytic properties of liver monoamine oxidases in such experimental pathological conditions as radiation damage, tumor growth, oxygen poisoning under high pressure, hypervitaminosis D , pulmonary tuberculosis, 2 hypercholesterolemia, and liver damage from ethanol, no other information was found in the available literatureonthis issue. To investigate changes in the processes of deamination of biogenic amines and other nitrogenous compounds in the mitochondria of hepatocytes, types of liver tissue damage caused by intoxication with hepatotropic poisons (allyl alcohol, hydrazine sulfate, CCl , ethyl alcohol) 4 were also chosen, where the precondition for the possible appearance of qualitative changes in thecatalytic activity ofmonoamineoxidase, as akey enzyme in themonoaminemetabolism,was the previously observed stimulation of lipid peroxidation processes in the tissue, as well as the https://ijmri.de/index.php/jmsi volume 4,issue2,2025 349 biochemical and electron microscopic identification of mitochondrial structure and function disturbance inhepatocytes. A significant role in the disruption of enzyme activity is played by the phenomena of destruction of parenchymal liver cells, as the activity of most enzymes is only manifested when theinternal structure of cells is preserved. In particular, itwas established that a shiftin thepH of the environment from the optimal reduces urea synthesis. The degree of manifestation of the liver's urea-forming dysfunction is closely dependent on the number of amino acids to be broken down in it.In somecases, liverdysfunction is moreevident under stress conditions. It was established that in patients with cirrhosis of the liver, with increasing protein load, hyperammonemia, hyperaminoacidemia, and encephalopathy, the protein level correlated with the maximum rate of urea synthesis. In natural conditions, such a specific protein load can be caused bybleeding from varicose veins oftheesophagus and stomach in patients with cirrhosis. The activity of enzymes catalyzing the process of deamination in the liver during acute and chronic diseases has been studied by a large number of researchers. The obtained data indicate various disturbances in the activity of liver aminotransferases during liver diseases. Alanine aminotransferase activity is significantly suppressed inthepresence of necrobiotic changes in the liver. A reliable decrease in the activity of both aminotransferases in liver tissue obtained surgically was observed, with the ratio of Aspartate Aminotransferase (AsAT): Alanine Aminotransferase (AlAT) being, on average, 1.5 times higher in cirrhosis compared to the control group. In liver diseases, due to disturbances in the processes of glycolysis and glycogenolysis, there is a