[Seasonal structural and functional changes in the rabbit heart]

A study was made of some characteristics of the function and ultrastructure of intact rabbit heart during varying seasons. These characteristics appeared markedly different in winter, spring, summer and autumn. During the development in the myocardium of pathological processes (as a result of aorta coarctation and diphtheritic intoxication), the amplitude of changes in some parameters that characterize the function and ultrastructure of the heart was decreased. The author concludes that it is advisable to make control experiments during the appropriate season while carrying out physiological and morphological investigations.

[Seasonal rearrangement of lipolytic processes and myocardial function in rabbits in hemodynamic overloading of the heart]

The interrelationship was investigated between the contractile function of the myocardium, the activity of some lipolytic enzymes in the body of rabbits and the blood content of free fatty acids under conditions of the hemodynamic heart overstrain in winter and summer. It was shown that winter is a less favourable season for the course of the above pathological process in the cardiac muscle as compared to summer.

[Relation of cardiomyocyte lysosomes to indices of function, metabolism and ultrastructure of the intact rabbit heart]

Twenty-eight physiological, biochemical and morphological parameters that characterize intact heart activity were studied during different seasons. The factor analysis made it possible to define two groups of the characteristics with a pronounced internal correlation. Analysis of the characteristics has demonstrated that the lysosomal apparatus of cardiomyocytes is involved in the maintenance of heart muscle contractility.

[Changes in the contractile activity of the left heart ventricle and blood content of free fatty acids during acute focal myocardial ischemia in rabbits at different times of the day]

Left-ventricular contractility and arterial blood levels of free fatty acids were studied experimentally in rabbits with acute focal myocardial ischemia at different hours of the day (12 a. m., 6 p. m., 12 p. m.). All parameters were measured before a myocardial acute-ischemia focus was created, and 15, 20 and 40 minutes after coronary artery ligation. Heart contractility and blood free fatty acid levels were shown to vary throughout the day. In acute focal myocardial ischemia, these parameters also show different patterns of variation. A relationship was demonstrated between the pattern of changes in some contractility indices under acute focal ischemia and blood baseline levels of free fatty acids, which was particularly manifest at 12 p. m., and grew very weak at 12 a. m.

[Effect of vitamins A and E on the contractile function of the heart in experimental myocardial infarction]

An experimental study in rabbits demonstrated that the animals treated with vitamins A and E (400 IU/kg and 0.4 mg/kg, respectively) in the presence of experimental myocardial infarction induced through ligation of the anterior descending coronary artery, showed a much more pronounced reduction of cardiac contractility as compared to the untreated animals with induced infarction or those treated with much higher doses (10000 IU/kg and 10 mg/kg, respectively). Vitamins A and E administered in small doses to intact animals and rabbits with experimental myocardial infarction produced marked damage of lysosome membranes, whereas high doses of vitamins had no similar effect in either intact or experimental-infarction animals.

Morphometric analysis of the rabbit myocardium after chronic ethanol feeding - early capillary changes

Male rabbits were fed with ethanol for 3 weeks. 10 ml of a 20% ethanol solution were applied daily with a stomach tube. The macroscopic, histologic and ultrastructural investigation of the hearts did not reveal and structural alterations. Morphometrically, the endothelial cells of the capillaries were changed, whereas the muscle cells did not show any abnormalities. The quantitative data indicate that the numerical density of endothelial cells is increased, whereas the volume density is not changed. This type of quantitative reaction pattern may be characterized as "proliferation" of endothelial cells. The proliferation is possibly related to ethanol-induced metabolic changes similar to chronic hypoxia. On the other hand, there is some evidence that the alteration is part of a general activation of mesenchymal cells in various organs after ethanol ingestion. The alteration is probably an early stage of the proliferation of capillaries.

[Effect of large heparin doses on the contractile function, structure and lipid metabolic indices of the myocardium in intact rabbits]

The effect of large doses (700 U/kg daily for 6 days) of heparin on the heart contractile function, myocardial morphology, content of free fatty acids in the blood, and the activity of tri- and monoglycerin lipase in blood plasma and heart tissue of intact rabbits was studied 24, 72 hours and 6 days after the beginning of heparin administration. It was established that the activity of lipolytic enzymes intensified, the concentration of free fatty acids in blood plasma grows, and the myocardial contractility increases after heparin administration. The phase structure of the cardiac cycle is simultaneously disturbed slightly. It is concluded that the intensification of lipolysis plays a role in increasing the myocardial contractility.

[Morphofunctional features of the left ventricle of rabbits with experimental alcoholic cardiomyopathy]

In chronic alcoholic poisoning the rabbits demonstrate an abrupt decrease in heart left ventricular contractility and a significant noticeable prolongation of the phases of isometric effort and isometric relaxation. The morphologic study of the heart showed marked myocardial hypertrophy and enhanced intramyocardial lypolysis leading to accumulation of acid lipids by the cardiac muscle. It seems likely that these lipids requiring additional oxygen amounts for utilization give rise to relative hypoxia in the myocardium. In conjunction with diastolic inadequacy this can lead to attenuation of the heart contractility and to compensatory development of myocardial hypertrophy.

[Various characteristics of lipid metabolism in experimental myocardial infarct and their effect on myocardial contraction]

It was established in rabbit experiments that in acute focal myocardial ischemia induced by ligation of the descending branch of the left coronary artery, diminution of the force of cardiac contractions and an increase in the content of free fatty acids in blood plasma are observed. Progressing intramyocardial lipolysis is noted for 6 days. Lipolysis blockade with large doses of nicotinic acid leads to an extremely sharp drop in the contractile force of the heart in experimental animals with acute focal myocardial ischemia and to drastic damage of the myocardial ultrastructures as well as to disorders of the metabolism of intracellular lipids.

[Lysosome activity in mice during rejection of a heterotopic heart implant]

Allotransplantation of the heart from newborn mice C57B1/6 into the pinna of adult CBA mice on the 3rd day after operation led to increased acid phosphatase activity and activation of the Golgi apparatus. Numerous lysosomes whose membrane became disrupted on the 7th-9th day from the time of implantation appeared later. At the same time histochemical study demonstrated local loss of acid phosphatase activity and a diffuse staining (brown) of the cytoplasm. No destruction of the lysosome membranes or release of the enzymes into the cytoplasm occurred in case of heart isografts (CBA-GBA).

[Comparative evaluation of the ultrastructure of the left atrium before and after mitral commissurotomy]

The left atrium myocardium of patients with mitral stenosis was subjected to electron microscopy with quantitative analysis of the pictures prior to and 10-15 minutes following mitral commissurotomy. The control was served by the left atrium myocardium of a man free from mitral disease, the specimen being obtained during surgery for an anterior mediastinum lypoma. In the left atrium myocardium of patients with mitral stenosis changes were revealed that demonstrated a severe decompensation of both the energy and contractile apparatus of the cardiac myocytes. Following mitral commissurotomy the activity of the bioenergy apparatus of the cardiac cells normalizes.

[Morphologic basis for several myocardial metabolic disorders in the presence of respiration uncoupled from phosphorylation]

It was experimentally established that the destruction of mitochondria due to a reduction of ATP production and to their compensatory hyperfunction under energy defecit is underlying some disorders in the myocardial metabolism caused by 2,4-DNP intoxication. Energy deficit results in K+ metabolism disorders and the related acetylcholine synthesis which predisopses the changes in the cardiac function and still further increases the myocardial requirements of energy. The bio-energy disorders develop in a vicious circle manner, and when the intoxication increases, it inevitably results in energy depletion and cardiac arrest.