Intracellular rearrangements of the rat contractile myocardial apparatus during prenatal ontogenesis after alcohol influence

Abstract

Background. Information on the formation of the contractile apparatus of the heart and the distribution of myofibrils in cardiomyocytes under conditions of intrauterine intoxication with ethanol remain a subject of considerable debate. The aim of the study was to determine changes in the ultrastructure of the contractile apparatus of rat ventricular cardiomyocytes during prenatal development in conditions of intrauterine alcohol intoxication. Methods. The object of the research was the hearts of rat posterity at different times from birth to adulthood in the model of chronic alcohol intoxication of the maternal organism. Quantitative parameters of cardiomyocyte myofibrils in different zones of the ventricular myocardium were determined using transmission electron microscopy. Results. In newborn rats, after exposure to ethanol, the values of the parameters in the subendocardial zone were statistically significantly increased in the left ventricle by 101.0% and in the right ventricle by 42.0%, compared to the indicators of the previous day of development. Indicators in the intramural and subepicardial zones were not significantly different from the corresponding values on the 20th day of prenatal ontogenesis. The difference between the parameters of different parts of the interventricular septum was statistically significant and amounted to 45.9% in the left ventricular part and 20.2% in the right ventricular part. The values of the parameter in the intramural zone after ethanol exposure decreased by 35.5% (p>0.05) in the left ventricle and by 36.0% (p<0.05) in the right ventricle compared to the norm. Conclusion. Chronic alcohol intoxication in prenatal cardiogenesis damages the contractile apparatus of ventricular cardiomyocytes due to disorganization of the structure of sarcomeres, fragmentation and disorientation of myofibrils, significant inhibition of sarcomere genesis, and a decrease in the content of myofibrils, which is associated with destruction of mitochondria. The severity of changes in these structures depends on the zone and period of development of the embryo. The most significant changes are due to the direct toxic effect of ethanol and occur in the early stages of cardiogenesis.