Biomedical subjects

I M Vikhliantsev

Publications and source records attributed to I M Vikhliantsev.

11 recordsLinked to original sources

PubMed2006

[Creatine as a metabolic controller of skeletal muscles structure and function in strength exercises in humans. The cellular mechanisms].

The effects of creatine oral supplementation combined with a 10-week resistive training of morphometric, contractile and molecular characteristics of human vast lateral muscle fibers were studied. 2 groups consisting of 9 young healthy men each were involved in resistive training of knee extensors for 10 weeks. Volunteers of the first group received per os 20 g of creatine for the 1st week of training and 5 g for the rest of the experimental training period. We found a significant increase of slow and fast-twitch fiber size in both trained groups and a significant increase of Ca-sensitivity of skinned single fiber contractility in creatine-supplemented group. The serum creatine phosphokinase activity in blood samples taken 24 hours after exercise session increased in all stages of the experimental training in both groups. At the same time, the adaptive decrease of the after-exercise CK concentration was observed in the placebo but not in the creatine-supplemented group. The altered integrity of the subsarcolemmal dystrophin layer was revealed in both groups after training.

Adult↗

PubMedDate not supplied

[Changes in the isoform composition of the cytoskeletal protein titn--adaptation process in hibernation].

Changes in the isoform composition of the elastic protein titin from skeletal and cardiac muscles of hibernating ground squirrels were revealed for the first time. It was shown that, upon hibernation, the molecular mass of titin decreases and its functional properties change as compared with the active state of the animal. The physiological significance of the changes in titin isoform composition for the inhibition of muscle contractile activity upon hibernation is discussed in connection with similar changes during some cardiomyopathies.

Animals↗

PubMedDate not supplied

[Properties of C protein from skeletal and cardiac muscles of the ground squirrel Citellus undulatus at various stages of hibernation].

Changes in the molecular weight and functional properties of the C and X proteins from skeletal muscles and the C protein from the cardiac muscle of hibernating ground squirrels Citellus undulatus at different stages of the hibernation were studied. A decrease in the molecular weight of the C protein from fast fibers of skeletal muscles of hibernating ground squirrels compared with awakening and active animals was revealed. The appearance of shorter molecules of the C protein upon hibernation was accompanied by a lowering of its capacity to enhance the actin-activated ATPase activity of control myosin and by the inhibition of its Ca(2+)-sensitivity. No similar changes were observed for the skeletal X protein and the cardiac C protein. The influence of the skeletal C protein on the main functional properties of myosin allows one to draw a conclusion about its contribution to the inhibition of contractile activity of skeletal muscles upon hibernation. The physiological significance of the changes in the C protein upon hibernation is discussed in connection with similar changes in some cardiomyopathies.

Actomyosin↗

PubMedDate not supplied

[Phosphorylation of sarcomeric cytoskeletal proteins--an adaptive factor for inhibiting the contractile activity of muscle during hibernation].

The influence of phosphorylation in vitro of the sarcomere cytoskeletal proteins titin and X-protein of skeletal muscles as well as C-protein of cardiac muscle of ground squirrel Citellus undulatus on the actin-activated ATPase activity of myosin and its Ca2+ sensitivity was studied. It was shown that phosphorylation lowers the activating effect of titin and C-protein and increases the inhibitory effect of X-protein on the enzymatic properties of actomyosin. The phosphorylation of the proteins has the most pronounced influence on Ca2+ sensitivity of actomyosin: it drops to a greater extent in the presence of phosphorylated C-protein and titin and is completely inhibited by phosphorylated X-protein. The inhibitory influence of phosphorylation in vitro of sarcomere cytoskeletal proteins on the above functional properties of the actomyosin system as well as the increase in the extent of phosphorylation of titin in vivo upon hibernation allow one to conclude that this posttranslation modification contributes to adaptive mechanisms of suppression of the contractile ability of muscles in this period.

Animals↗

PubMedDate not supplied

[Sarcomeric cytoskeletal proteins and myosin phenotype in stretched soleus of hindlimb-suspended rats].

Changes in sarcomeric cytoskeletal proteins of rat m. soleus fibers upon the chronic stretching against the background of gravitational unloading were analyzed and compared with changes in fiber size and myosin phenotype. For rats exposed to gravitational unloading in the usual microgravity-simulating experimental model (hindlimb suspension (HS) according to Morey-Holten), a considerable reduction in the mass of m. soleus (by 54%) and the area of its fibers of both slow-twitch (by 47%) and fast-twitch (37%) types compared with control animals was revealed. Moreover, the percent of fibers containing only slow isoforms of myosin heavy chains (MHC) for suspended animals was slightly smaller and the portion of fibers interacting only with antibodies against fast myosin isoforms was significantly higher than for control animals. For hindlimb-suspended rats, the titin/MHC and nebulin/MHC ratios appeared to be reduced almost by two times as compared with those for the contriol group of animals. Chronic immobilization of m. soleus in stretched state against the background of suspension leads to a partial or complete prevention of the reduction in muscle fiber sizes, the transformation of the myosin phenotype into fast one, and a decrease in relative content of sarcomeric cytoskeletal proteins.

Animals↗

PubMedDate not supplied

[Adaptive behavior of titin isoforms from skeletal and cardiac muscles of ground squirrels (Citellus undulatus) during hibernation].

By the use of modified SDS electrophoresis in agarose-strengthened 2% polyacrylamide gels, the adaptive behavior of titin isoforms in skeletal and cardiac muscles of ground squirrels (Citellus undulatus) during hibernation was studied. The presence of two titin isoforms (short and long) with molecular weights approximately 3700 and approximately 3800 kDa in m. soleus, approximately 3400 and approximately 3600 kDa in m. psoas, approximately 3000 and approximately 3400 kDa in the left ventricle of myocardium was found. It was found that the content of the short titin isoform in the above muscles of hibernating and arousing ground squirrels is considerably lower than that of the long titin isoform. The preservation of the long titin isoform in skeletal and cardiac muscles of hibernating and arousing ground squirrels can be regarded as an evolutionarily determined adaptive mechanism favoring the survival of animal under extreme conditions without pathological consequences.

Animals↗

PubMedDate not supplied

[Human soleus fibers contractile characteristics and sarcomeric cytoskeletal proteins after gravitational unloading. Contribution of support stimulus].

The effects of support withdrawal and support stimulation on the contractile characteristics of human soleus fibers and cellular factors which influence them were studied. The experimental model of the "dry" head-out water immersion was used in the study. In this model, the hydrostatic pressure on different sites of the body surface are equal so that the experimental conditions are close to the complete supportlessness. A 7-day exposure to dry immersion resulted in a decrease in the maximal isometric tension of the skinned fibers, a decline in the myofibrillar Ca2+-sensitivity, and the relative loss of the titin and nebulin content. A significant decrease in the percentage of fibers containing slow myosin heavy chains was also observed after dry immersion. The application of the mechanical stimulator influencing the plantar support zones with a pressure of 0.2 +/- 0.15 kg/cm2 6 times a day for 20 minutes of each hour brought about a complete prevention of the above listed effects of dry immersion. The data obtained allow one to conclude that the decline in maximal tension and Ca2+-sensitivity as well as myosin shift and loss of sarcomeric cytoskeletal proteins are associated with the support withdrawal during the exposure to dry immersion.

Cytoskeletal Proteins↗

PubMedDate not supplied

[The behavior of titin and the proteins of its family from skeletal muscles of ground squirrel (Citellus undulatus) during hibernation and rats under conditions of simulated microgravity].

By the use of SDS PAGE, the behavior of titin and MyBP-C in fast (m. psoas) as well as titin and MyBP-X in slow (m. soleus) muscles of ground squirrels (Citellus undulatus) during hibernation was compared with the behavior of titin and MyBP-X in rat m. soleus under conditions of simulated microgravity. A decrease in the amount of titin 1 and MyBP-C relative to that of myosin heavy chains by approximately 30% and approximately 40%, correspondingly, in muscles of hibernating and arousing ground squirrels was revealed in comparison with active animals. No differences in the relative amount of MyBP-X in m. soleus of hibernating, arousing and active ground squirrels were found. Under conditions of simulated microgravity, a decrease in the amount of titin 1 by approximately 2 times and MyBP-X by approximately1.5 times relative to that of myosin heavy chains in rat m. soleus was observed. By the method of SDS PAGE modified by us, an almost twofold decrease in the amount of short isovariants of the titin N2A isoform relative to that of myosin heavy chains was shown in muscles of hibernating and arousing ground squirrels, whereas no changes were found in the amount of long titin isovariants. The conditions of simulated microgravity resulted in a twofold decrease in the relative amount of both short and long titin isovariants in rat m. soleus. The results indicate that hibernating ground squirrels have an evolutionarily determined adaptive mechanism of selective degradation of fast muscle fibers and preservation or increase of slow fibers, as the most economic and energetically advantageous, with proteins typical of them. The microgravitation of nonhibernating animals (rats) leads to a non-selective degradation of MyBP-X and titin isovariants, which contributes to considerable atrophy of soleus fibers.

Adaptation, Physiological↗

PubMedDate not supplied

[Myosin light chains of skeletal and cardiac muscles of ground squirrel Citillus undulatus in different periods of hibernation].

The isoform composition of myosin light chains and the extent of their phosphorylation in skeletal and cardiac muscles of ground squirrel Citellus undulatus in different periods of hibernation were studied. Regulatory myosin light chains of skeletal muscles of hibernating ground squirrels were completely dephosphorylated, while 25% of these light chains in active animals were phosphorylated. During hibernation, a shift of isoform composition of essential and regulatory skeletal muscle myosin light chains toward slower isoforms was observed, which is evidenced by the data obtained on m. psoas and on the totality of all skeletal muscles. In the atrial myocardium of hibernating ground squirrels, ventricular myosin light chains 1 (up to 60%) were registered. In contrast, during arousal of ground squirrels, in ventricular myocardium the appearance of atrial myosin light chains 1 (up to 30%) was revealed. A possible role of posttranslation changes in myosin light chains and their isoform shifts in the hibernation scenario is discussed.

Animals↗

PubMedDate not supplied

[Seasonal changes in phosphorylation of myosin regulatory light chains and C-protein in myocardium of hibernating ground squirrel Citellus undulatus].

A comparative study concerning the extent of phosphorylation of myosin regulatory light chains and C-protein from the left ventricle of hibernating ground squirrel Citellus undulatus during the periods of hibernation and activity was carried out. During hibernation, regulatory light chains of ground squirrel were found to be completely dephosphorylated. In active animals, the share of phosphorylated light chains averages 40-45% of their total amount. The extent of phosphorylation of the cardiac C-protein during hibernation is about two times higher than that in the active state. Seasonal differences in phosphorylation of the two proteins of ground squirrel myocardium are discussed in the context of adaptation to hibernation.

Animals↗

PubMedDate not supplied

[Titin isoforms].

The titin isoform composition in skeletal and cardiac muscles of humans and animals has been studied using SDS elecrtophoresis in agarose-strengthened 1.3-2.3% polyacrylamide gels modified by us and immunoblot analysis in order to reveal new titin isoforms with molecular weights of more than 3700 kDa. The experimental data obtained have provided a basis for the suggestion that the titin bands of high molecular weights discovered by us are intact titin isoforms, while the titin bands designated on electrophoregrams as N2A, N2B and N2BA isoforms are their fragments.

Animals↗