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V A Levtov

Publications and source records attributed to V A Levtov.

At least 19 recordsLinked to original sources
PubMed1991

[The effect of the dynamic component in the mechanical deformation of the vessels on the blood supply to the skeletal muscles].

Dynamic and static distension of the cat m. gastrocnemius by 10-20% of initial length induced similar hyperemia provided the same amplitude of the distension and a common impulse of passive strength are preserved. The post-elongation hyperemia did not depend on changes in the blood flow during distension or on increase in the number of dynamic components of the distension. Isolated application of muscle vibration induced post-vibration hyperemia whereas the combination of the 8-24 Hz vibration with continuous distension of the muscle exerted no effect on the parameters of the post-elongation hyperemia.

Animals↗
PubMed1991

[The effect of high-molecular compounds on the rheological properties of the blood and on the reactivity of the skeletal muscle vessels].

The administration of polymers into the vascular bed of the m. gastrocnemius and in vitro did not affect the postocclusion hyperemia but in changed the venous outflow from the muscle, the change having a phasic character. The effects of concentrations and molecular mass of the polymers on the blood rheological properties were more obvious in vitro. Dextran-20 thousand most favourably affects the blood viscosity whereas the least favourable one belongs to polyoxyethylene-20 thousand. The polymers with molecular mass about 500 thousand in small concentrations reduce the viscosity of the blood, in larger concentrations they enhance it increasing the erythrocytes aggregation.

Animals↗
PubMed1989

[Blood supply of skeletal muscles in reactive hyperemia].

In 18 anesthetized cats, 60-sec occlusion of the m. gastrocnemius artery entailed a decrease in the muscle blood supply by 15-20 ml of the blood volume in the vessels whereas the post-occlusion increase in the blood flow restored the blood volume with 45% excess. The intravascular accumulation of the blood exerting a moderating effect upon the venous return while preserving the increased arterial inflow, can be regarded as an automatic way of limiting the hemodynamic excitation due to the postocclusion shifts and involved in systemic circulation. Papaverin interacts with the blood volume restoration and leads to insufficient restoration in the postocclusion period. This suggests that the postocclusion excessive restoration of the blood volume in muscle, as observed in control animals, can be due to an active vasodilatation of the capacitance portion of the intraorgan vascular bed.

Animals↗
PubMed1988

[Nocigenic changes in the blood viscosity indices of rats].

One-minute subcutaneous nociceptive stimulation increased arterial pressure by 15-20 mm Hg in Wistar rats. The 20-min. stimulation altered rheological properties of the blood: the hematocrit, the plasma viscosity and protein concentration, the erythrocyte aggregation velocity, the utmost tension of shift, and the viscosity of the blood standardized by hematocrit--all these parameters increased. These changes are rather unfavourable for flowing properties of the blood. The changes of the blood rheological properties were reflex-based, the problem of compensatory shifts is discussed.

Animals↗
PubMed1986

[Aggregation of erythrocytes placed in macro- and micro-cuvettes].

Changes of the intensity of light reflected or passing through cuvette with the blood specify the degree of blood aggregation. The parameters of light reflection by the surface of blood in macro-cuvette are compared with those of light passage through a thin micro-cuvette with preliminarily stirred blood. The latter technique enables a direct microscopy of the erythrocytes aggregation. Virtually similar results were obtained with blood of different animals and with different values of hematocrit. The data suggest a correlation between velocity of the aggregation and increase of the hematocrit value. Causes of discrepancies of the absolute values of parameters under study are discussed.

Animals↗
PubMed1985

[Hyperemia in capillaries of the gastrocnemius muscle following stretching].

Microcine-tv-study of the isolated m. gastrocnemius' capillaries in 9 anesthetized cats determined the blood flow mean velocity as 0.73 +/- 0.12 mm/s with a considerable dispersion for 216 capillaries (variation coefficient = 120-160%). The temporal dispersion of velocities in a single capillary was insignificant (variation coefficient about 45%). Longitudinal stretch of the muscle for 1-2 cm decelerated the capillary blood flow up to its complete arrest. After 1-min stretch, the blood flow velocity increased by 0.30 +/- 0.06 mm/s in 148 capillaries; decreased by 0.22 +/- 0.07 mm/s in 35 capillaries and remained the same in 5 capillaries. Apart from this, 4 capillaries initially invisible, became apparent. Average data for capillaries corresponded to those of macro-experiments. Responses of individual capillaries seem to be unrelated to initial velocity of their location within the net, if only absolute values of velocities are to be analysed.

Animals↗
PubMed1985

[Role of compression of the vessels of the gastrocnemius muscle in changes in its blood supply during stretching].

In the m. gastrocnemius of anesthetized cats, the pressure of tissue resistance balancing was 5 mm Hg initially and developed a 7-fold increase in longitudinal stretch of the muscle by 10-20% when the total mechanical tension increased 20-fold (from 2400 to 47 662 H/m2) and the blood flow reduced from 5.0 to 3.0 ml . min-1 (100 r)-1. Decrease of the blood flow in stretching and the postelongation hyperemia could not be reproduced in external compression of the muscle equal to the balancing pressure at a given stretching. Only the external pressure 50 and 100 mm Hg decelerated the blood flow and developed a hyperemia even though a lesser one than the postelongation hyperemia. The effect of longitudinal muscle stretch on its vessels is not limited by their compression with the "intramuscular pressure".

Animals↗
PubMed1985

[Topography and hydrodynamic heterogeneity in the terminal bed of the vessels of the gastrocnemius muscle of the cat].

The cine-TV technique acided to reconstruct the in vivo pattern of the vascular bed surface in the m. gastrocnemius of anesthetized cats. Existence of microvascular elements (modules) was confirmed as regularly repeated every 400-500 mus along the muscular fibers. A module includes transversal (oblique) precapillary arteriole and postcapillary venule interconnected with 3-12 parallel capillaries. Mean blood velocity in the capillaries was initially 0.73 +/- 0.12 mm/sec and during postelongation hyperemia it was 0.91 +/- 0.13 mm/sec, the velocity being slower in distal capillaries. This diversity was reduced in postelongation hyperemia. Mathematical modelling of blood flow distribution over different types of modules showed the blood flow velocity in the capillaries to depend on the ratio: total resistance of incoming and outgoing vessels against the resistance of the capillary part. Along with diminishing of the ratio, the diversity of perfusion must also diminish which has been corroborated in the course of experiments.

Animals↗
PubMed1977

[Relationship between metabolic and hemodynamic characteristics during isometric tetanus of the cat gastrocnemius muscle].

In anesthetized cats, the increase in duration of the isometric tetanic contraction of the m. gastrocnemius from 7 to 30 sec elicited a 4-fold increase in the muscular mechanical performance. During the postcontraction hyperemia, a 5-6-fold increase in the rate of lactic acid and inorganic phosphates removal into venous blood were opposed to only a 1.5-2-fold increase in the blood supply and oxygen consumption by the muscle. The role of metabolic and metabolic factors in the mechanism of hyperemia in skeletal muscle after strong tetanic contractions is discussed.

Animals↗