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Biomedical subjects

Z A Podlubnaia

Publications and source records attributed to Z A Podlubnaia.

At least 19 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↗
PubMed1990

[The use of cryomethods for research on the sarcomere ultrastructure of rabbit skeletal muscles].

The ultrastructure of sarcomeres of glycerinated rabbit psoas muscle was studied using freeze-fracture-etching, freeze-drying and optical diffraction techniques in comparison with the investigation of this muscle by plastic sections and negative staining methods. In frozen and dried myofibrils isolated from the above muscle the stripes of minor proteins location in A- and I-disks were clearly seen. The pivot structure in thick filaments was revealed in longitudinal fractures of the muscle. The ordered arrangement of myosin heads (crossbridges) associated with actin filaments was preserved in frozen longitudinal fractures as evidenced by optical diffraction. Freeze etching technique allowed to revealed some details of Z-line structure: alpha-actinin bridges connecting the ends of actin filaments of neighbouring sarcomeres and to preserve the lateral struts between actin filaments in I-disks.

Animals↗
PubMed1989

[Interaction of aldolase with thin filaments within I-disks, isolated from skeletal muscles].

Using electron microscopy and optical diffraction, Ca2+-dependent binding of a glycolytic enzyme (aldolase) to thin filaments of isolated skeletal muscle I-disks have been revealed. On the micrographs of negatively stained I-disks the cross-striation determined by troponin-tropomyosin complex distribution has a period of about 38 nm. The width of troponin-tropomyosin stripes is 5-6 nm. On the optical diffraction patterns from isolated I-disks the meridional reflections measuring 38.5, 19.2, 12.8 nm are present. On the micrographs of isolated I-disks, treated with aldolase in the absence of Ca2+ (1 mM EGTA) the width of periodic transverse stripes (period approximately 38 nm) increases from 5-6 nm to 25-28 nm due to the interaction of aldolase with thin filaments. On the optical diffraction patterns from I-disks treated with aldolase in the absence of Ca2+ (1 mM EGTA) the strong meridional reflection equal to 38.5 nm is present, while the reflections equal to 19.2 nm are absent. The optical diffraction patterns from I-disks treated with aldolase in the presence of Ca2+ (greater than or equal to 10(-5) M) do not, as a rule, differ from those obtained from I-disks not treated with aldolase, i.e. they contain the three above reflections. The binding of aldolase to thin filaments in the absence of Ca2+ is the reason of disappearance of meridional reflections equal to 19.2 and 12.8 nm.

Animals↗
PubMed1986

[Determination of quantitative parameters of the binding of F-protein (phosphofructokinase) with myosin and localization of binding sites on the myosin molecule].

To determine the localization of F-protein binding sites on myosin, the interaction of F-protein with myosin and its proteolytic fragments in 0.1 M KCl, 10 mM K-phosphate pH 6.5 was studied, using sedimentation, electron microscopic and optical diffraction methods. Sedimentation experiments showed that F-protein binds to myosin and myosin rod rather than to light meromyosin or S-1. The F-protein binding to myosin and rod is of a similar character. The calculated values of the constants of F-protein binding to myosin and rod are 2.6 X 10(5) M-1 and 2.1 X 10(5) M-1, respectively. The binding sites are probably located on the subfragment-2 portion of the myosin molecule. The number of F-protein binding sites on myosin calculated per chain weight of 80 000 is 5 +/- 1. The sedimentation results were confirmed by electron microscopic data. F-protein does not bind to light meromyosin paracrystals, but decorates myosin and rod filaments with the interval of 14.3 nm regardless of whether F-protein is added before or after filamentogenesis. A comparison of optical diffraction patterns obtained from myosin and rod filaments with those from decorated ones revealed a marked enhancement of meridional reflection at (14.3 nm)-1 in the latter case.

Animals↗
PubMed1985

[Z-line structure of the rabbit psoas muscle studied by negative contrast staining].

The ultrastructure of the Z-disc of the rabbit psoas muscle was elucidated by electron microscopy using negative staining technique. Conclusions summarized from this work are as follow: (a) Z-disc involves two layers of Z-filaments, i.e. connecting filaments, which bind thin filaments of adjacent I-discs in the Z-line region. These layers are spaced about 380 A apart. (b) Z-filaments measure 380 A X 30 A. (c) The angle between the connecting filaments and the thin filaments depends on ionic conditions and varies from 20 degrees to 90 degrees. (d) We conclude that alpha-actinin is a structural component of Z-filaments, since dimensions of Z-filaments and their interaction with thin filaments are similar to those of alpha-actinin.

Actinin↗
PubMedDate not supplied

[Absence of seasonal adaptive changes in the isoformic state and functional properties of actin-containing and thin filament proteins in skeletal muscles of hibernating squirrels].

The data indicating the absence of seasonal changes in the isoform composition and functional properties of actin and thin filament associated proteins from skeletal muscles of hibernating ground squirrels were obtained. Taking into account the data obtained earlier by the authors on significant qualitative and quantitative changes in isoform composition and functional properties of the other contractile protein, myosin, it is concluded that the suppression of contractile capacity of the executive apparatus of skeletal muscles of animals upon hibernation and its repair upon arousal are determined by the above adaptive changes in myosin.

Actins↗
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

[Changes in composition of cardiac myosin light chains in dilated cardiomyopathy: effect on functional properties].

A reduction (by 16-24%) in the amount of myosin regulatory light chains (LC2) in all heart sections of patients with dilated cardiomyopathy was found. The appearance of atrial essential light chains in ventricular myosin (up to 23%) not typical for this heart section in norm was also revealed. The decrease in LC2 content leads to a considerable inhibition of actin-activated ATPase activity and a loss of Ca2+ sensitivity of reconstructed filaments of myosin isolated from atria and ventricles of patients with dilated cardiomyopathy. The hybridization of myosin molecules from heavy chains of pathological human left ventricular myosin and light chains of pig left ventricular myosin leads to an increase in actin-activated ATPase activity of myosin and its Ca2+ sensitivity to the control level. The data suggest strongly the contribution of LC2-deficit to the distortion of functional properties of myosin in dilated cardiomyopathy. In contrast, the appearance of atrial LC1 in ventricle in dilated cardiomyopathy is a factor improving these properties.

Actins↗
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

[Changes in structure and functional properties of cytoskeletal elastic protein titin in dilated cardiomyopathy].

To elucidate the role of titin in the onset and development of dilated cardiomyopathy, the structure and functional properties of this protein from pathological myocardium (human left ventricle) were studied. By the use of SDS gel electrophoresis, a decrease in molecular weight of titin in dilated cardiomyopathy compared with norm (pig left ventricle) was revealed. The decrease correlated with the stage of the disease. A decrease in the length of molecules of pathological forms of titin was also found by electron microscopy, which confirms the results of electrophoresis tests. It was shown that, unlike titin from healthy muscle, pathological forms of titin do not activate but inhibit the main functional properties of control myosin: the actin-activated ATPase activity and its Ca2+ sensitivity. The direction of the changes in structure and functional properties of titin allows one to conclude about its contribution to the development of the pathology studied.

Adenosine Triphosphatases↗
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

[Structural and functional changes in myosin in chronic coronary insufficiency].

A study of myosin extracted from dog's cardiac muscle at different stages of chronic heart failure (from 1 week to 1 year) was carried out. A decrease of UV-luminescence intensity, flow birefringence and ATPase activity (to 70%) was observed. The electron microscopic investigation of myosin and LMM structure shows the loss of ability to form typical paracrystals by LMM, the electron microscopic appearance of the whole myosin being unchanged.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Role of atrial myosin light chains in modulating the functional properties of myocardium].

To elucidate the functional importance of the appearance of atrial myosin light chains (ALC) in ventricles in some cardiomyopathies, a partial (75%) substitution of myosin light chains 1 and 2 of the left ventricle for ALC-1 and ALC-2 was carried out in vitro. It is shown that this substitution does not lead to changes in shapes and sizes of the filaments formed by hybrid myosin but causes changes in the shape of myosin heads. The replacement of the light chains increases the actin-activated ATPase activity of hybrid myosin by 63%. The results obtained are evidence that the substitution of ventricle myosin light chains with atrial ones is of physiological importance for the improvement of myosin functional properties and thereby for the compensation of the insufficiency of myocardium in dilated cardiomyopathy. These data and the data on dynamics of ALC-1 in diseased ventricles are important for creating the prognostic test of dilated cardiomyopathy development based on the registration of changes in the isoform composition of cardiac myosin light chains.

Actins↗
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↗