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Contractile cardiomyocyte metabolism was studied by histochemical methods in experimental stenosis of the aorta complicated and not by heart failure. Acceleration of the citric acid cycle, more intense oxidation of free fatty acids and their metabolites, glycolysis intensification, and higher activity of shuttle mechanisms were found in the contractile cardiomyocytes in stenosis of the aorta not complicated by heart failure. The presence of these metabolic shifts in the myocardium of all studied compartments suggests their association with not only more intense heart work, but also with the effects of total systems neurohumoral factors. Comparative study of myocardial metabolism in two variants of experimental stenosis of the aorta has revealed changes prognostically unfavorable for the development of heart failure. These changes include exhaustion of glycogen reserve, glycolysis inhibition, and metabolism shift towards biosynthetic processes. These data indicate an important role of glycolysis in support of myocardial contractile function during the acute phase of pressure overloading of the heart.

The activity of the respiratory enzymes of myocardial mitochondria--succinatedehydrogenase and cytochromixidase--was studied in experimentally induced aortic stenosis and after its elimination in 98 mongrel dogs. The observation period of stenosis was 1, 15, 30 and 60 days, and after its elimination--1, 7, 15 and 30 days. The activity of the enzymes in question was found to grow after the production of aortic stenosis. The highest level of their enzymatic activity was observed on the 15th day after the induction of stenosis. By the 30th and 60th day the enzymatic activity underwent some decrease, although it persisted on a level above the initial. The activity of succinatedehydrogenase fell sharper. After the elimination of the stenosis the activity of both enzymes decreased, and by the 7th day it was below the initial level. By the 15th day after the removal of the ligature from the aorta the activity of both enzymes corresponded to the initial values and did not change further till the end of the 1st month. The dynamics of the activity of succinatedehydrogenase and cytochromixidase after an experimentally induced aortic stenosis and its subsequent elimination seems to depend on the nature of the changes in the function of the heart muscle performed under such experimental pathology, and on the degree of coronary flow enhancement.