[Electron microscope analysis of cardiomyocytes in the rat left ventricle under simulation of weightlessness effects and artificial gravitation].

Electron microscopic study of left ventricle cardiomyocytes and quantitative analysis of their mitochondriom was performed in rats exposed to tail-suspension, as a model of weightlessness effects, to artificial gravity produced by intermittent 2G centrifugation and a combination of these effects. It was found that the cardiomyocytes ultrastructure changed slightly after tail-suspension and after intermittent 2G influence, as well as under a combination of these effects. However, the number of intermitochondrial junctions increased significantly in the interfibrillar zone of cardiomyocytes under a combination of tail-suspension and intermittent 2G influence, which agrees with the cell hypertrophy described earlier.

[Protective effect of peptide semax the rat heart in acute myocardial infarction].

Semax, a member of ACTH-derived peptides family, has been employed in the treatment of acute ischemic stroke in patients. It decreased neurological deficit and reduced NO hyperproduction in the rat brain, caused by acute cerebral hypoperfusion. We suggested that semax is also able to protect rat heart from ischemic damage in acute myocardial infaction (AMI). AMI was induced by left coronary artery occlusion, myocardial ischemic area averaged 30 % of left ventricle. In 2 hours after coronary occlusion, the AMI group developed 11 % reduced mean arterial blood pressure and 48 % increased diastolic blood pressure in left ventricle in comparison with sham-operated control group. However, infusion of either dobutamine, which directly stimulates myocardial contractility, or sodium nitroprusside and phenylephrine, that change vascular resistance and thus cardiac afterload, did not reveal distinctions in hemodynamic parameters between groups. These data indicate absense or only moderate cardiac dysfunction in rats with AMI and are consistent wih morphometrical and histochemical studies that did not detect any necrotic or apoptotic (TUNEL-test) changes in left ventricular cardiomyocytes in spite of development of distinct ischemic disturbances of mitochondria and nuclear in about 50 % of cardiomyocytes in 2 hours after AMI. Semax (150 microg/kg), given i. p. 15 min and 2 hours after coronary occlusion, caused no effect on cardiac function, but completely prevented ischemia-induced ultrastructural changes of cardiomyocytes. This protective effect was accompanied by the ability of peptide to blunt the increase in plasma concentrations of nitrates, observed in AMI group.

[Electron microscopy description of cardiomyocytes from the left ventricle of rat heart after apoptosis induction by isoproterenol].

Changes in cardiomyocytes from the left ventricle of rat heart were studied by light and electron microscopic and morphometric methods in the myocardial regions neighboring necrotic foci formed after the injection of 80 mg/kg beta adrenomimetic isoproterenol. TUNEL assay was used to detect apoptotic cardiomyocytes. Three types of cardiomyocytes (A, B, and C) differing by the ultrastructure of the nucleus and the degree of mitochondrial changes were identified at all studied stages of necrotic focus development (4-48 h). B and C type cardiomyocytes could represent cells at different stages of apoptosis. The apoptotic changes in cardiomyocytes proved to prevail in early lesion foci (4-18 h), while cardiomyocytes at later stages were prone to necrosis; cardiomyocytes can exhibit signs of apoptosis and necrosis at the same time.

[Protective effect of peptide semax (ACTH(4-7)Pro-Gly-Pro) on the rat heart rate after myocardial infarction].

Semax, a member of ACTH-derived peptides family, was used in treatment of ischemic stroke in patients. It decreased neurological deficiency and reduced NO hyperproduction in the rat brain caused by acute cerebral hypoperfusion. We suggest that semax is also capable of protecting the rat heart from ischemic damage 28 days after myocardial infarction (MI) induced by left descendent coronary artery occlusion. Semax (150 microg/kg) was given i. p. in the operating day twice: 15 min and 2 hours after coronary occlusion, and once a day for the following 6 days. In 28 days after infarction, the MI group developed cardiac hypertrophy, cell growth was caused mainly by the increase of contractile filaments not supported by the appropriate mitochondrial growth that indicated an impaired energy supply of the cells. Moreover, cardiac hypertrophy was accompanied by decreased mean arterial blood pressure and cardiac contractile function and increased left ventricular end-diastolic pressure. Pharmacological change of cardiac afterload revealed that, in 28 days after MI, the rat heart was not able to change its contractile performance in response to either increase or decrease of systemic blood pressure, and as a result could not maintain its diastolic pressure. All these changes obviously reflect development of heart failure. Semax did not affect cardiac work but partially prevented end-diastolic pressure growth in left ventricle as well as ameliorated cardiomyocyte hypertrophy and disproportionate growth of contractile and mitochondrial apparatus, thus exerting beneficial effect on the left ventricular remodeling and heart failure development late after myocardial infarction.

Electron microscopic study of left ventricular cardiomyocyte mitochondriom in rats subjected to head-down tilt.

The mitochondriom of left-ventricular cardiomyocytes in rats subjected to head-down tilt was studied at the electron microscopic level. The ultrastructure of individual mitochondria was disturbed and the number of intermitochondrial contacts in the perinuclear zone increased after 30-day head-down tilt. These parameters did not return to normal over 30 days after 30-day tilt. Repeated 14-day head-down tilt led to a more pronounced increase in the number of intermitochondrial contacts, mitochondria with abnormal ultrastructure were still observed.

[Adaptive responses of the secretory cardiomyocytes of the right atrium during simulation of the long-term and repeated gravity by antiorthostatic suspension of rats]. / Adaptivnye reaktsii sekretornykh kardiomiotsitov pravogo predserdiia pri modelirovanii dlitel'nogo i povtornogo deistviia ponizhennoi sily tiazhesti metodom antiortostaticheskogo vyveshivaniia krys.

Reactive changes in right atrium cardiomyocytes during antiorthostatic tail suspension of rats commonly used to simulate low gravity have been studied by electron microscopy and morphometry. A 14 day suspension proved to increase contractile and secreting activities of cardiomyocytes. At the same time, signs of depleted activity are observed in some cells. Elongation of the experiment to 30 days leads to development of adaptive compensatory responses and increases their secreting capacity. A 30 day return to normal orthostatic position does not completely restores the structure and functioning of cardiomyocytes and leads to accumulation of internal secretion. A repeated 14 day suspension to a certain extent facilitates cardiomyocyte adaptation to altered conditions as compared to a single exposure; apparently, secretion release decreases while its production is activated.

[Changes in mitochondria and inter-mitochondrial junctions of the rat cardiomyocytes upon adrenergic stimulation by isoproterenol]. / Izmenenie mitokhondrioma i mezhmitokhondrial'nykh kontaktov v kardiomiotsitakh serdtsa krys pri adrenergicheskoi stimuliatsii izoproterenolom.

Changes in rat cardiomyocytes and their mitochondria and intermitochondrial junctions (IMJs) upon beta-adrenoreceptor stimulation with isoproterenol were studied by the methods of light and electron microscopy and computer-aided morphometry. It was found that isoproterenol injections (0.3 mg/kg for eight days) resulted in myocardial hypertrophy, which was more pronounced in the right than in the left ventricle. In the hypertrophied cardiomyocytes of both ventricles, an adaptive response of mitochondria was observed: their ultrastructure, size, and number changed, and the number and average length of IMJs increased. A positive correlation between the degree of cell hypertrophy and the number of IMJs was revealed. The reactive properties of mitochondria, including IMJ formation, differed depending on their location in the cell (i.e., in the paranuclear, intermyofibrillar, or subsarcolemmal regions). These results suggest that the rates and intensities of adaptive compensatory processes developing in the mitochondria of cardiomyocytes exposed to beta-adrenoreceptor stimulation differ in the left and right ventricles.

[Morphometric and ultrastructural characteristics of cardiomyocyte mitochondriome of the left ventricle in rats exposed to hypergravity]. / Morfometricheskaia i ul'trastrukturnaia kharakteristika mitokhondrioma kardiomiotsitov levogo zheludochka krys v usloviiakh gipergravitatsii.

For the first time, electron-microscopic morphometric analysis of the mitochondrial system in cardiomyocytes of the left ventricle was performed in rats exposed to hypergravity (2G) After five days of exposure, the number of long mitochondria sharply increased in the interfibrillar zone of cardiomyocytes. The numbers of inter-mitochondrial junctions (IMJ) were increased in all zones of mitochondria localization. The ultrastructure and numerical density of mitochondria remained within the normal range. Similar changes were also revealed on day 19 (the end of exposure), but the numbers of IMJ in the perinuclear and subsarcolemmal perivascular zones were lower than on day 5. One months after the end of 19-day exposure at 2G, the test parameters of the mitochondrial system did not return to the norm. Apparently, this is why the repeated exposure to hypergravity (2G for five days after 30-day rest) failed to evoke a similar response from the mitochondrial system of cardiomyocytes.

[Ultrastructural and morphometric characteristics of cardiomyocyte mitochondriomes of several invertebrate species. II. Heart ventricle cardiomyocyte mitochondriome of several gastropod mollusks]. / Ul'trastrukturnaia i morfometricheskaia kharakteristika mitokhondrioma kardiomiotsitov nekotorykh vidov bespozvonochnykh zhivotnykh. II. Mitokhondriom kardiomiotsitov zheludochka nekotorykh briukhonogikh molliuskov.

The mitochondrial ultrastructure in ventricle cardiomyocytes of three gastropod molluscs (Clione limacina, Helix pomatia, Lymnaea stagnalis) has been studied. Mitochondria in cardiomyocytes of these molluscs are connected by intermitochondrial contacts of the same morphology as intermitochondrial contacts in vertebrate cardiomyocytes. Their numbers in cardiomyocytes of the above molluscs being, respectively, 61, 35.1 and 29.2 contacts per 100 mitochondria. In Clione limacina cardiomyocyte contractile elements located on the periphery of cell occupy 21.1% of the cytoplasm volume. Mitochondria form a core making large dense central accumulations taking up 54.9% of the cytoplasm volume. Numerous mitochondria have vesicular or tubular cristae and light matrix. Unlike cardiomyocytes of Clione limacina, in Helix pomatia and Lymnaea stagnalis contractile material predominates in cardiomyocytes occupying 43.7% and 49.2% of the cytoplasm volume, respectively. Mitochondria located on the periphery and in the center of cardiomyocytes in Lymnaea stagnalis and Helix pomatia occupy 31 and 32.5% of the cytoplasma volume, respectively. Mitochondria in cardiomyocytes of both these molluscs have plastic cristae and dense matrix. The differences in cardiomyocyte mitochondriom organization in the studied molluscs can be explained by different functional heart loading in these due to different levels of their locomotor activity.

[Ultrastructure and morphology of the mitochondriome of cardiomyocytes from invertebrates. I. The mitochondriome of cardiomyocytes from insects]. / Ul'trastrukturnaia i morfologicheskaia kharakteristika mitochondrioma kardiomiotsitov nekotorykh vidov bespozvonochnykh zhivotnykh. I. Mitochondriom kardiomiotsytov nekotorykh nasekomykh.

The cardiomyocyte mitochondrial ultrastructure of two insect species (the American cockroach Periplaneta americana, and a dragonfly Aeschna sp.) has been studied. Mitochondria in cardiomyocytes of these insects are connected by intermitochondrial contacts, similar in morphology to vertebrate intermitochondrial contacts. The number of intermitochondrial contacts differs in cardiomyocytes of the studied insects, numbering 12 and 18 per 100 mitochondria in cardiomyocytes of the cockroach and dragonfly, respectively, which is due presumably to differences in activity of these insects. Cardiomyocytes of both species have several features in common. It was shown that cross-striated myofibrils oriented in different directions occupy 50-58% of the cytoplasmic volume, while mitochondria cover only 16-18%. The pattern of mitochondrial localization differs in cardiomyocytes of the two studied insects. In the cockroach, cardiomyocyte mitochondria are seen both in the center of the cell and on its periphery, in protrusions; whereas in the dragonfly, mitochondria of cardiomyocytes are confined to the protrusions of the abluminal cell side. Mitochondrial profiles are small, their packing is not dense. Mitochondria in cardiomyocytes of these insects have few plastic cristae and dense matrix.

Responses of rat left ventricle cardiomyocytes to constant 2G-hypergravity.

2G-hypergravity during 33-days led to hypertrophy of cardiomyocytes (CMC) in rat left ventricle accompanied by capillary number and diameter growth. CMC ultrastructure was normal at all experimental stages. Number of intermitochondrial junctions (IMJ) rose after 33 days of 2G in subsarcolemmal pericapillary zone of CMC, indicating probably to enlarged CMC energy needs. Changes in myocardium achieved during 33 days of 2G were reversible at 39 days of 1G (except IMJ number). Repeated 5-days 2G influence (after 33 days of primary 2G influence followed by 39 days of 1G) led again to CMC hypertrophy and to IMJ number rise in all zones of mitochondria localisation. Primary 5-days 2G influence didn't result in CMC hypertrophy, IMJ number rose only in subsarcolemmal pericapillary zone.

Influence of 2G-hypergravity on the right atrium secretory cardiomyocytes of rats.

For elucidation of secretory cardiomyocytes adaptation to prolonged and repeated influence of changed gravity the ultrastructural and morphometrical analysis of right atrium cells was made in rats after they were exposed to primary and repeated 2G-centrifugation in ground-based experiment. It was found prolonged 2G-hypergravity resulted in hypertrophy of right atrium cardiomyocytes and stimulated of their mitochondrial associative activity and granular secretion; repeated influence induced changes differed from those after single influence.

[Intermitochondrial contacts in a system of cardiomyocyte mitochondriome in a normal state, under physiological stress, and in pathology]. / Mezhmitokhondrial'nye kontakty v sisteme mitokhondrioma kardiomiotsitov v norme, prei fiziologicheskikh nagruzkakh i v patologii.

Intermitochondrial contacts are universal and indispensable structures participating in the formation of mitochondriome in cardiomyocytes of invertebrate and vertebrate animals; they participate in the maintenance of the energy pool required for rhythmic contractions of the heart. At the ultrastructural level, a direct relationship is demonstrated between the functional load on the heart and the number of intermitochondrial contacts in cardiomyocytes of swifts and rats: there was a twofold increase in the number of these contacts associated in actively flying adult birds as compared with chicks; a similar effect was observed in response to pressure overload associated with aortal stenosis; hypokinesia and hypoxia led to a twofold or even threefold decrease in their number.

Mitochondria of the heart left ventricle in hypokinetic rats.

The response of cardiomyocytes and the mitochondrial system of rats subjected to a four-month hypokinesia was studied. Morphometric light microscopic analysis of cardiomyocytes of the left ventricle revealed an increase of the area of cell cross sections, whereas the number of capillaries remained the same in the normal heart, which was suggested to be a weak adaptive response. In electron microscopy, along with normal cardiomyocytes, cells with the swollen sarcoplasm and degrading myofibers were observed, which indicated a partial atrophy of the heart muscle. Heterogeneous ultrastructural changes of mitochondria were also observed. Some organelles were swollen. Mitochondria with unusual dark cristae and mitochondria with cristae in a "twisted" configuration were found. The number of intermitochondrial junctions considerably decreased in all regions of mitochondrial location which is presumably related to the decrease in the functional cell activity under experimental hypokinesia.

[The electron microscopic study of the cytoplast mitochondria of an ESK cell culture after the action of actinomycin D. Embryonic swine kidney]. / Elektronno-mikroskopicheskoe issledovanie mitokhondrii tsitoplastov kletok kul'tury SPEV posle deistviia aktinomitsina D.

The inhibitor of RNA synthesis actinomycin D substantially changed mitochondrial morphology and ultrastructure of cytoplasts in comparison with mitochondria of intact cells. These changes included an increase of matrix condensation, the number of cristae, and extension of intercristal and intracristal spaces. We suggest that mitochondria are characterized by significant independence from the nucleus that possibly controls a considerable part of mitochondrial RNA.

[Changes in mitochondrial function in the cells and cytoplasts of a pig embryo kidney culture as affected by the action of actinomycin D]. / Izmenenie funktsional'nogo sostoianiia mitokhondrii v kletkakh i tsitoplastakh kul'tury SPEV pri deistvii aktinomitsina D.

Vital staining of PE kidney cells by fluorescent cationic dye, ethyl rhodamine, (accumulated inside mitochondria by the membrane potential and hence reflecting their functional state) shows rather close level of the fluorescence intensity both in cells and in their cytoplasts for 10 hours of culture survival in the standard medium. In cells and cytoplasts cultivated in the medium with 0.2 mg/ml of actinomycin D inhibiting RNA synthesis, fluorescence intensity of mitochondria sharply decreases after 10 hours as against the control patterns. It is concluded that mitochondria possess a significant degree of autonomy of the nucleus and it is supposed that a considerable part of mitochondrial RNA is under the nucleus control.