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N A Levkova

Publications and source records attributed to N A Levkova.

15 recordsLinked to original sources

[Quantitative ultrastructural characteristics of the myocardial mitochondria of hypokinetic rats].

Experiments on rats under 30-day hypokinesia have shown an increase in the mitochondrial area in perinuclear, myofibrillar and subsarcolemmal zones of the cardiomyocyte pericaryon, accompanied by a concurrent rise in the number of crests. The crest density index and the amount of mitochondria in te pericaryon diminish. These changes are considered as compensatory-adaptive reconstitution of hypertrophic nature in response to partial destruction of mitochondria. During the observation period this reconstitution is not completed and thus underlies the decreased contractility and functional reserves of the heart in hypokinesia.

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[Effect of embryonal organ-specific RNA on myocardial hypertrophy].

The relative weight of the heart and the thickness of muscular fibers in the left ventricular myocardium of rats were evaluated 70-91 and 120-227 days after creating stenosis of the abdominal portion of the aorta. Half of the animals were inoculated with cardiac type-specific embryonal RNA, the rest of the animals being intact. The data were treated by the variational statistical technique, by dispersion and mathematic analyses. Administration of RNA decreased the rate of myocardial hypertrophy development.

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[Synaptoarchitectonics of the ganglia of the celiac plexus in white rats].

In 50 intact white rats at the age of 6, 15, 23 and 30 months synapsoarchitectonics of the celiac plexus nodes was studied by an electron microscopy method. Peculiarities in synapsoarchitectonics are stipulated by pericaryon processes in neurons, some of them have no contacts with the axonal terminals, while others have contacts with the axonal terminals. The former include small (about 0.5 mkm) drop-like and large (up to 1.5 mkm) polymorphous processes within the limits of perisomatic membrane, as well as processes penetrating the neuronal capsule. All of them contain, in different combinations, vesicles, ribosomas, fibrillae, and the largest processes--small cisterns of granular cytoplasmatic network and single mitochondria. The processes of the first group are considered as original stages for the development of the second group processes. The latter are represented by different in size (about 1.0--2.0 mkm) in form (digital, cone-, pin-, goblet-shaped, cylindrical, branching) and in content formations. There is, as a rule, one contact on the processes of an uncomplicated form, while on the branching processes there can be up to three and more contacting axonal terminals. Peculiar features in the composition of the processes taken as a whole (specific forms, absence of dendritic tubes, sometimes numerous contacts with axonal terminals in spite of small size) distinguish them from newly forming dendritic processes and these formations are considered as independent specialized receptor apparatus in the pericaryon of neurons of the celiac plexus.

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[Ultrastructural organization of chromaffin paraganglia in the ganglia of the solar plexus].

Under study was the ultrastructural organization of chromaffin cells in the nodes of the solar plexus of albino rats. The chromaffin cells form accumulations--paraganglia, bent for capillaries. The chromaffin cells are of small size and have a dense glial capsule. The cytoplasms are rich in mitochondria, Golgi Complexes and vesicles containing catecholamines. The state of cytoplasmic components speaks of asynchronous secretory activity of chromaffin cells. Among catecholamine-containing vesicles three main types can be distinguished, different is size, structure of the content and localization in the perikaryon. Excretion of catecholamines in realized through cytoplasmic processes which, getting free of the glial capsule, come out directly to capillaries. The coordinating influence of the sympathetic nervous system on the endocrinous function of chromaffin paraganglia of the solar plexus is exercised by paraganglionic fibres, whose terminal portions form synaptic contacts on the chromaffin cells.

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