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Biomedical subjects

M M Umnova

Publications and source records attributed to M M Umnova.

At least 19 recordsLinked to original sources
PubMed2000

[Ultrastructural characteristics of rat neuromuscular junctions after physical load].

It is interesting to ascertain the adaptive reaction of rat neuromuscular junctions (NMJ) of muscle fibers of different types to a chronic physical load. We examined ultrastructural changes in NMJ following both static load (pre- and postnatal ontogenesis of Wistar rats till a 2 month age took place under a constant rotation on the centrifuge at hypergravity conditions 2G), and after three kinds of dynamic loads (1/run on treadmill with a speed 35 m/min for 6 wks, 10-60 min/day; 2/swimmings, each 10 hrs/day for 10 days; 3/strength exercises on a vertical treadmill with load for 6 wks). Differences in NMJ reaction of muscle fibers of the same type to various loads were established. A low secretory activity of axonal terminals of type I muscle fibers of m. soleus was shown after the static load. The dynamic load (run) is accompanied with a high secretory activity of axonal terminals in m. soleus type I muscle fibers and of some axonal terminals of m. quadriceps femoris IIB type muscle fibers after strength exercises; the secretory activity of axonal terminals of m. quadriceps femoris IIA and IIB types muscle fibers is expressed in a lesser degree after swimming. The NMJ ultrastructure remodelling (terminal renewal) of type I muscle fibers of the 2 month old control rats increases after static and dynamic (run) loads. Some correlations between different kinds of physical load, muscle fiber type and the degree of NMJ ultrastructure transformation have been shown.

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PubMed1991

The effect of increased functional load on the activation of satellite cells in the skeletal muscle of adult rats.

The comparison of the number of satellite cells in the fast oxidative glycolytic muscle fibers of m. quadriceps femoris in males of normal Wistar rats aged 16-17 weeks (5 animals) and rats trained for endurance (5 animals) was made. After six weeks of treadmill running at a speed of 35 m/min in an increasing regimen, the number of satellite cells in trained animals (9.59 +/- 1.09%) increased over 2.5-fold in comparison to controls (3.41 +/- 0.26%) within 24 hours. At the ultrastructural level complete and focal injuries of some muscle fibers and the partial denervation of individual muscle fibers were recorded in trained rats. It was proposed that the focal functional denervation of muscle fibers could be one of the factors for the activation of satellite cells in endurance exercise. Some trained rats demonstrated small groups of extra- and perisynaptic satellite cells under the basal membrane of muscle fibres, partial detachment of satellite cells from the surface of muscle fiber and presence in the interstitial space cell containing filaments.

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PubMed1988

[Ultrastructure of neuromuscular synapses during administration of dexamethasone].

Dexamethasone administration to rats at a dose of 100 micrograms/100 g body weight for 10 days resulted in the appearance of large synaptic vesicles in axon terminals, migration of synaptic vesicles to synaptic slits, local broadening of synaptic slit, proliferation of mitochondria in pre- and postsynaptic zones of the axomuscular synapses, destruction of myofibrils and other organelles in the postsynaptic area and the presence of lysosomes in this region.

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PubMed1988

[Neurotrophic regulation of the restorative processes in muscle autografts in vertebrates].

In frogs, tortoises and rats autotransplantation of the whole gastrocnemius muscle has been performed into its own bed at sewing the nerve to the autotransplant and at its denervation. Fragments of the skeletal muscles are also transplanted into the brain and into the spinal cord in frogs and rats. By means of light and electron microscopy, restorative processes are studied in the transplanted muscles. Acceleration of histomorphogenesis of the muscular and nervous tissues is stated from the lower toward the higher Vertebrata. When the transplants are deprived of the connection with the nervous system, the cause of the form organization process in all the animals investigated is disturbed, however, the nervous-trophic regulation is of the greatest importance in the mammalia. The experiments reveal mutual regulation of the plastic activity in the nervous and muscular tissues, that becomes more intensive in the course of evolution.

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PubMed1986

[Reaction of intact skeletal muscle on the transplantation of minced muscle tissue].

The experiments on rats have revealed that grafting of minced muscle tissue to unaffected gastrochemical muscle of the same animal leads to active regeneration in the graft accompanied by the formation of myogenic elements. In the zone of unaffected muscle contact with the graft the plastic state of muscle tissue was observed: sarcoplasm basophily of muscle fibers, groups and chains of round nuclei in them, the presence of satellite cells, ultrastructural changes, indicative of metabolic activity of the muscle fibers. With the resorption of the graft, these phenomena in the unaffected muscle gradually disappeared.

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PubMed1985

[Ultrastructural changes in the red muscle fibers of the quadriceps muscle of the rat femur during increased motor activity].

Experiments on rats were made to study the effect of physical exercise running in a treadbahn on ultrastructure of skeletal muscle fibers. The biphasic mechanism of muscle contractile activity was shown. The processes of destruction occurring in red muscle fibers of the intensely working quadriceps femoris were manifested by enlargement of T system and sarcoplasmic reticulum elements, mitochondrial matrix swelling, cryst destruction, vacuolar degeneration of part of the mitochondria, and destruction of individual myofibrils. In addition to destructive changes, the muscle exhibited the recovery processes--physiological regeneration. Those processes included large accumulations of the mitochondria beneath the plasma membrane of muscle fibers, the presence of small mitochondria, division of the mitochondria, transformation of myosatellitocytes to myoblasts, the presence of centrioles in endotheliocytes, and so forth.

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