Lesions of ventricular cardiomyocytes in experimental massive pulmonary embolism]

The damage of ventricular myocardial cells during acute experimental massive pulmonary embolism (MPE) was studied by light, polarization and electron microscopy on anaesthetized dogs. In cases, when MPE was followed by heart failure, the deep ir reversible damage of myofibrils took place, and the relative volume of myofibrils decreased in both ventricles. The damage of right ventricular myocardium, which works against increased postload during MPE, may be reason of right ventricular insufficiency.     

Modeling of massive embolism of the pulmonary artery in experimental animals

In anesthesized dogs with closed chest and natural respiration massive embolism of pulmonary artery has been simulated with the aid of marked muscular emboli. In 6 h after massive pulmonary embolism pressure in the lesser circulation somewhat decreased, however, it was higher than the initial and control data.     

Seasonal changes in the cardiomyocytes of heterothermal animals

In 20 Citellus erythrogenys the volumetric and surface densities of myofibrils, mitochondria, sarcoplasmic reticulum, T-system and lipid drops were estimated in cardiomyocytes by means of stereological methods before, during and after hibernation. The volumetric and surface-volumetric ratios for the main intracellular compartments were calculated. Certain morphological criteria were found for the seasonal peculiarities in the structural organization of cardiomyocytes in the hibernating rodents. During hibernation, myocardial atrophy (seasonal regression of the heart weight and decreasing diameter of cardiomyocytes) takes place. It is accompanied with an adaptive rearrangement of the cardiomyocyte ultrastructure. The latter facilitates to myocardial contractility at low body temperatures at the expense of activation of the cellular transport-energic interaction system.     

Structural changes in the pulmonary vessels and parenchyma in experimental hypercholesterolemia and atherosclerosis

Light and electron microscopy were employed to study the microcirculatory bed (MCB), intraorganic vessels and lung tissue in rabbits in the first hours (1, 3, 6, 15, 24 and 48 h) after a single administration of cholesterol (ChS) and in the course of the development of experimental atherosclerosis. The MCB demonstrated changes such as dilatation of the venular part, arteriolar constriction, red cell aggregation in capillaries and venules, and stases. At the early stages of experimental atherosclerosis induced by the diet the permeability of the air-blood barrier and the synthesis of lung surfactant were found to be deranged. Vessel-tissue changes in the lungs progressed with an increase in the length of the diet (1-8 months) and were alike the picture seen in chronic nonspecific lung diseases, particularly in what is called senile emphysema. A relationship was established between the degree of changes in the MCB and HCh gravity. Atherosclerotic lesions in the intraorganic arteries occur and progress parallel with the development of this process in the intramural arteries of the myocardium. The data obtained attest to an important role of lipid metabolism disorders in the development of lung pathology and may have a certain significance in specifying the pathogenesis of chronic nonspecific lung diseases, especially.     

Evolution of blood vessels of the heart wall

In progressive development of the organisms, the cardio-vascular system perfects, its construction is adequate to the level and character of the animal's metabolism. The hypobranchial arteries, forming in the subbranchial area in fishes, make the immediate source for the branching off the coronary arteries. Comparison of the data concerning the places where the cranial coronary arteries take their origin in amphibia, reptiles, birds and mammalia demonstrates that the evolutional process is directed towards transference of the places of their branching off on the ventral aorta, and then on the nearest distance to the heart. Certain data are obtained on evolution of the blood circulation pathways in the myocardium and, particularly, on presence of blood vessels in the spongy myocardium in Elasmobranchii, Chondrosteoideii, as well as in the alligator. The most important of the myocardial blood vessels at all stages of evolution is their connection with the cardiac chambers. At definite stages of phylogenesis, simultaneously with compactization of the myocardium and formation of veins from the intertrabecular spaces, the subepicardial and intramural veins unite into a single venous system, bringing blood to the cardiac cavity. In birds, mammalia and human being, the coronary vessels have reached a high degree of development, having penetrated by their branches into all layers of the cardiac wall, and thus they exclude the dependence of the myocardial blood supply from the blood that is present in the cardiac cavity.     

r-Galactonolactone in experimental galactosemic animals

An accumulation of galactose-1,4-lactone, an oxidation product of galactose, was observed in various tissues of galactosemic guinea pigs fed a 40% galactose diet for 6 weeks. In addition, an accumulation of the two galactose metabolites varied among organs. The highest content of the lactone was observed in the liver and the content of the lactone exceeded that of the reduced counterpart. The lens gave the highest galactitol content. In the serum the level of the lactone was very low. A trace amount of the lactone was detected in the kidney while it was mostly excreted into urine within 54 h upon withdrawal of the diet. On the other hand, in the animals kept on a high galactose diet for only 2 days, urinary lactone rapidly decreased. These observations indicated that a high galactose level in the circulation was associated with the production of the lactone in various tissues and that the accumulated lactone was released into the circulation very slowly and then excreted into the urine. Suppression of galactitol production by administration of an aldose reductase inhibitor resulted in the accumulation of the lactone in the lens, the testis, and the muscle, as well as in the circulation. The lactone thus produced was excreted exclusively into the urine. This observation indicates a close relationship between the oxidative and reductive metabolisms of galactose at a toxic level.     

Megakaryocytes in rabbit pulmonary blood vessels

Semiserial sections of lung capillaries of seven rabbits were examined for megakaryocytes. Triads of serial sections of each lobe were examined, and megakaryocyte counts per cm2 were determined. Median megakaryocyte count was determined for each lobe. The lobal values were used to calculate the was determined for each lobe. The lobal values were used to calculate the median cell-counts for each experimental animal. Values of 0.16-0.64 megakaryocytes per cm2 were established as "normal".     

Altered reactivity of pulmonary vessels in postobstructive pulmonary vasculopathy.

Chronic ligation of one pulmonary artery results in pulmonary vascular remodeling and bronchial angiogenesis, collectively known as postobstructive pulmonary vasculopathy (POPV). To investigate pulmonary vascular reactivity in POPV, we ligated the left main pulmonary artery of guinea pigs and, after 1-10 mo, prepared explants by inflating lungs with agarose and sectioning them into approximately 1-mm-thick slices; we measured areas of pulmonary vessels and determined contractile responses to histamine and serotonin (5-HT) and relaxant responses to ACh and sodium nitroprusside. We found maximal contractions of arteries to 5-HT (24. 4 +/- 2.6%) and of veins to histamine (53.9 +/- 4.7%) were significantly increased in POPV of 3-mo duration compared with those of controls (16.8 +/- 1.5 and 40.8 +/- 5.0%, respectively). Relaxation of arteries with ACh was enhanced at 10 mo but not at 1 mo after ligation. Relaxation with sodium nitroprusside was increased in veins at 1 mo after ligation but was not altered in arteries. Morphometry revealed reduced diameters of arteries and veins without increased medial thickness. Our data suggest that the enhanced contractile responses of pulmonary vessels to histamine and 5-HT in POPV were not a result of endothelial dysfunction or of structural alterations but might be caused by as-yet-undiscovered mechanisms.     

Cysteinyl-leukotriene receptors in pulmonary vessels.

Two categories of cysteinyl-leukotrienes have been proposed, namely, CysLT1 and CysLT2. These receptors are found not only on the vascular smooth muscle but also on the endothelium. Activation of the receptor(s) on vascular smooth muscle provokes contraction whereas activation of the receptors on the endothelium produces contraction and/or relaxation. These endothelium dependent effects are due to the release of both contractile and relaxant factors derived from the endothelium. While factors derived from either the cyclooxygenase or nitric oxide pathways are involved, in some vascular preparations other mediators such as endothelin may be involved. However, in isolated human pulmonary vascular preparations, this appears not to be the case and presently the nature and origin of the contractile factor remains to be established.     

Temperature regulates the arrhythmogenic activity of pulmonary vein cardiomyocytes

Temperature plays an important role in the electrophysiology of cardiomyocytes. Pulmonary veins (PVs) are known to initiate paroxysmal atrial fibrillation. The effects of temperature on the arrhythmogenic activity of rabbit single PV and atrial cardiomyocytes were assessed using the whole-cell clamp technique. PV cardiomyocytes had different beating rates at low (22-25 degrees C), normal (38-39 degrees C) and high (40-41 degrees C) temperatures (0.9 +/- 0.1, 3.2 +/- 0.4, 6.4 +/- 0.6 Hz, respectively; p < 0.001). There were different action potential durations and incidences of delayed afterdepolarization in PV cardiomyocytes with pacemaker activity (31, 59, 63%; p < 0.05), PV cardiomyocytes without pacemaker activity (16, 47, 60%; p < 0.001), and atrial myocytes (0, 0, 21%; p < 0.05). However, oscillatory afterpotentials were only found in PV cardiomyocytes with pacemaker activity at normal (50%) or high (68%) temperatures, but not at low temperatures (p < 0.001). Both PV and atrial cardiomyocytes had larger transient inward currents and inward rectified currents at high temperatures. Additionally, PV cardiomyocytes with and without pacemaker activity had larger pacemaker currents at higher temperatures. This study demonstrated that PV cardiomyocytes have an increase in arrhythmogenic activity at high temperatures because of enhanced automaticity, induced triggered activity, or shortening of action potential duration.