[Dynamics of lesions to the myocardium in experimental hyper- cholesterolemia]

Dynamics of changes in the myocardium of rabbits subjected to food hypercholesterolemia lasting from 6 to 16 weeks was investigated. An intensification of coronary atheromatosis was proportional to the duration of the high-cholesterol diet. There were observed focal and growing in time damages of cardiomyocytes. They were sharply outlined in atherosclerotically changed coronary arteries. The following morphological and histochemical changes have been observed: increased acidophilia and fuchsinophilia in the single and grouped muscle fibres, foci of infiltrations by mononuclear cells, contraction bands, and outlines of myocardial fibres, separation of myofibrils, granular disintegration of cardiomyocytes, healed infarcts, depletion and excessive accumulation of glycogen in muscle fibres, presence of neutral fats, cholesterol and its esters in atheromatous plaques of coronary arteries, presence of neutral fats in some cardiomyocytes: focal acid phosphates, loss of activity of Mg- and Ca-dependent ATPases and SDH: oedema of mitochondria with disorganization of cristae, disorganisation of fibres and lysis of myofilaments, margination of chromatin in cardiomyocyte nuclei, increased number of lysosomes, intensified symptoms of egzocytosis, widening of channels of sarcoplasmatic reticulum, oedema of endothelium of capillary vessels and increased number of the collagenous fibres in the interstitial space. The results of histological, histochemical and microscopic-electron investigations correlated with each other. It may be considered that the observed damages of cardiomyocytes precede myocardial infarction and result from progressive and increasing ischemia, hypoxia and accumulation of fat substances and cholesterol and its esters in intima of coronary arterioles as well as in cardiomyocytes.