The computer-vibromyography as a biometric progress in studying muscle function

Muscular vibrations were recorded from different relaxed and contracted skeletal muscles in human subjects, with the use of a piezo-electric device. Simultaneous wire-EMG recordings were performed. Spectral analysis of the acceleration curves (vibromyograms) disclosed muscle and function dependent compound frequency patterns. We suggest that the activity of motor units including the action of central reflex loops and oscillatory driving is mainly responsible for the muscular vibrations. Other sources are discussed. Computer-Vibromyography as a mechanical ensemble measurement supplements bioelectric EMG techniques and classical tremor analysis and provides further insights into the function of muscle and motor-system.     

Role of light chains of myosin in the regulation of contraction of vertebrate striated muscles

The data of the study on Ca²⁺ sensitivity of ATPase activity of myosin from vertebrate striated muscles in the presence of actin and the conditions of its manifestation and disappearance are presented. The role of Ca²⁺ sensitivity of actin-activated myosin ATPase in the regulation of contraction of vertebrate striated muscles is discussed.     

Responses of muscle spindles of fast and slow muscles to mechanical stimulation during hypokinesia

Activity of muscle spindles of fast (extensor digitorum longus) and slow (soleus) muscles was studied in cats during hypokinesia of the limb immobilized in a plaster cast. Spontaneous activity of muscle spindles of the fast and slow muscles was unchanged during hypokinesia. Spontaneous activity of primary and secondary endings evoked by passive stretching of the muscle exceeded normal. During stretching of the muscles at different speeds and of different amplitudes, the discharge frequency of the primary and secondary endings was much greater than normally during both the dynamic and the static phase of stretching. These changes were more marked in the slow muscles.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 10, No. 2, pp. 186–192, March–April, 1978.     

The influence of hypokinesia on free calcium cation content in myocytes of rat skeletal muscles and myocardium

The influence of hypokinesia on the content of free Ca²⁺ and the level of NAD(P)H in myocytes of rat skeletal muscles and myocardium, and microviscosity of myocyte membranes was investigated. It has been found that hypokinesia increased the free Ca²⁺ content and NAD(P)H level in myocytes of skeletal muscles and myocardium. Alterations of structural-functional properties of membrane that appeared as an increase of membrane fluidity in the regions of lipid bilayer and protein-lipid contact were observed only in skeletal muscles. It was supposed that an increase of calcium cation level in myocytes stimulated the activity of enzymes involved in the apoptosis process that results in the decrease of muscle tissue mass.     

Na+/K+-ATPase activity of different types of striated muscles

Na+/K+-ATPase activity was determined in striated muscles with different aerobic capacities. The underlying hypothesis was that different aerobic capacities are reflective of different contractile activity which imposes greater demands on sarcolemmal ion translocation and may thus set Na pumping capacity. The added ion translocation demands required during exercise-training on Na+/K+-ATPase activity in different muscle fiber types may require an adaptation of this enzyme. The highest and lowest Na+/K+-ATPase activity was in the heart and white gastrocnemius muscle (WG), respectively. A high linear correlation existed between Na+/K+-ATPase activity and succinate dehydrogenase activity in the six muscles studied. Exercise-training did not increase Na+/K+-ATPase activity in any of the muscles, but did increase the aerobic capacity, except in the heart and WG. It was concluded that Na+/K+-ATPase activity has a high positive correlation with the aerobic capacity of striated muscles in the rat and that the Na pump capacity does not adapt to exercise-training of 1 hr X day-1 as does aerobic capacity.     

Energy-dependent transport of Ca2+ and lipid peroxidation in the sarcoplasmic reticular membranes of rats during hypokinesia

Thirty-day hypokinesia in Wistar rats did not affect the rate of Ca2+ transport and the activity of Ca-ATPase in light and heavy fractions of sarcoplasmic reticulum of primarily white muscles. As hypokinesia was raised up to 90 days, these indicators increased. The intensity of lipid peroxidation in sarcoplasmic reticulum was lower in hypokinetic animals.     

Ontogenetic Development of Creatine Phosphokinase in Skeletal Muscles and Heart from Pigs

Creatine Phosphokinase (CPK) in striated muscles shows only small changes in activity before birth. After birth and during the first month of extrauterine life the activity increases rapidly. The largest increase is seen in muscles with a glycolytic energy metabolism (m. long, dorsi) and the smallest in muscles with an oxydative energy metabolism (m. flexor dig. ped. sup.). The differences between these groups of muscles are statistically significant. In heart tissue the increase in CPK activity is lower, the levels amounting to 40 to 47 % of those in striated muscles. Early in fetal life only the BB isoenzyme is found in striated muscles. Synthesis of M subunits of GPK starts between day 76 and 65 before birth and increases rapidly after this time leading to disappearance of the BB isoenzyme 24 days prior to birth and of the MB isoenzyme at birth. In muscles with an oxydative as well as in muscles with a glycolytic metabolism all GPK activity after birth is caused by the MM isoenzyme. All three isoenzymes are present in heart tissue at the earliest prenatal stage investigated, the pattern being dominated by the BB isoenzyme. During further differentiation the MM isoenzyme increases and the BB isoenzyme decreases. The development is completed during the first month after birth with a final isoenzyme composition of 81 % MM and 19 % MB isoenzyme. kw|Keywords|k]pigs; k]ontogenesis; k]creatine phosphokinase; k]activity; k]isoenzymes     

Dehydrogenase activity in skeletal muscles of rats after long-term exposure to weightlessness

Malate- and isocytratedehydrogenase activity in mitochondrial and cytoplasmic fractions and lactate dehydrogenase activity in hindlimb muscles have been studied at different stages after 18.5-day flight on a biosatellite "Cosmos-1129" and after 20-day hypokinesia. A decrease in dehydrogenase activity has been found on the first postflight day. The enzyme activities returned to the control values in mitochondria, and in the cytoplasm they were greater by day 6 postflight. It was concluded that hypokinesia did not reveal all the effects of microgravity on the whole system but some enzyme alterations in the muscle resembled those observed during the flight. The effects may be caused by the inhibition of both aerobic and anaerobic metabolic pathways under the effect of microgravity.     

Species-independent expression of nitric oxide synthase in the sarcolemma region of visceral and somatic striated muscle fibers

The expression and distribution of nitric oxide synthase (NOS) was studied by use of the newly designed specific histochemical NADPH diaphorase staining method and the indirect immunofluorescence technique employing an antiserum to brain NOS in visceral and somatic striated muscles of several mammalian species. Histochemical activity and immunoreactivity were located in the sarcolemma region of type I and II fibers of all muscles investigated. Visceral muscles were more strongly stained than somatic muscles. Furthermore, type II fibers, identified by staining of myosin adenosine triphosphatase activity after pre-incubation at alkaline pH, were more intensely labeled than type I fibers. In addition, NOS activity was detected in the area of the sarcolemma of intrafusal fibers. No obvious differences between species were observed. It was concluded that NOS of striated muscles probably makes up the richest and most important nitric oxide source in mammals.     

Role of calcineurin in striated muscle: development, adaptation, and disease

Striated muscles, cardiac and skeletal muscles, use calcium as a second messenger to respond and adapt to environmental stimuli. Elevations in intracellular calcium activate calcineurin, a serine/threonine phosphatase, resulting in expression of a set of genes involved in remodeling striated muscle. Activation of calcineurin in hearts produces cardiac hypertrophy, and in skeletal muscle promotes cell differentiation and transforms fiber type specificity. In this review we discuss the effects of calcineurin activity on development, adaptation, and disease of striated muscle.     

Seasonal changes in proteolytic activity of calpains in striated muscles of long-tailed ground squirrel <Emphasis Type="Italic">Spermophilus undulatus</Emphasis>

Seasonal changes in proteolytic activity and content of calpains in striated muscles of the longtailed ground squirrel Spermophilus undulatus were studied by casein zymography and Western blotting analysis. The results testify to hyperactivation of calpain proteases in the skeletal muscles of awakened animals during the “winter” activity. The observed changes are discussed in the context of adaptation of skeletal muscles of long-tailed ground squirrels to hibernation.     

Subcellular distribution and some properties of alanine aminotransferase in striated muscles of the crayfish, trout, carp, frog, pigeon and rabbit.

Subcellular distribution and some physicochemical properties of alanine aminotransferase in striated muscles of the crayfish, trout, carp, frog, pigeon and rabbit were studied. It was established that: (1) Alanine aminotransferase activity in all mentioned animals occurred almost entirely in the cytosolic fraction of the muscles. Total activity and activity per mg protein were highest in crayfish and pigeon muscles and lowest in carp and trout muscles. (2) The pH optimum for the muscles of homoiotherms and poikilotherms ranged from 7.5 to 8, Km values for L-alanine were of the order 10(-3)--10(-2) M and those for alpha-ketoglutarate 10(-4) M. (3) A 10 degree C temperature increase of the incubation medium was accompanied by a 70--90% increase in activity. (4) The higher the alanine aminotransferase activity of the muscles, the relatively higher their alanine production during electrical stimulation. (5) From the above results it is concluded that alanine aminotransferase in striated muscles regulates the rate of glycolysis and energy production under conditions of anaerobiosis through the formation of alanine.     

Expression and activity of cyclooxygenase isoforms in skeletal muscles and myocardium of humans and rodents.

Conflicting data have been reported on cyclooxygenase (COX)-1 and COX-2 expression and activity in striated muscles, including skeletal muscles and myocardium, in particular it is still unclear whether muscle cells are able to produce prostaglandins (PGs). We characterized the expression and enzymatic activity of COX-1 and COX-2 in the skeletal muscles and in the myocardium of mice, rats and humans. By RT-PCR, COX-1 and COX-2 mRNAs were observed in homogenates of mouse and rat hearts, and in different types of skeletal muscles from all different species. By Western blotting, COX-1 and -2 proteins were detected in skeletal muscles and hearts from rodents, as well as in skeletal muscles from humans. Immunoperoxidase stains showed that COX-1 and -2 were diffusely expressed in the myocytes of different muscles and in the myocardiocytes from all different species. In the presence of arachidonic acid, which is the COX enzymatic substrate, isolated skeletal muscle and heart samples from rodents released predominantly PGE(2). The biosynthesis of PGE(2) was reduced between 50 and 80% (P < 0.05 vs. vehicle) in the presence of either COX-1- or COX-2-selective blockers, demonstrating that both isoforms are enzymatically active. Exogenous PGE(2) added to isolated skeletal muscle preparations from rodents did not affect contraction, whereas it significantly fastened relaxation of a slow type muscle, such as soleus. In conclusion, COX-1 and COX-2 are expressed and enzymatically active in myocytes of skeletal muscles and hearts of rodents and humans. PGE(2) appears to be the main product of COX activity in striated muscles.     

Some mechanisms of voluntary control of walking in humans

The electrical activities of some muscles of the lower extremities have been studied by the method of presentation of an acoustic signal for a change in walking speed. It has been established that the motor response to a signal has two stages, at which (1) the ratio of muscle activities facilitating acceleration or deceleration of walking is formed and (2) the muscle activity corresponding to the new rate of locomotion is set. The latent period of the first stage of the motor response depends on the temporal relationship of the signal and the phase of muscle activity: it is minimum if the signal coincides with the phase of activity and maximum if the signal is given in the phase of bioelectric silence. It may be supposed that the voluntary control of the locomotion rate is related to at least two types of cortical effects: cyclic and acyclic. The former determine the transition from one speed of walking to another through changing human body posture characteristics (probably, they influence interneurons and motoneurons of reflex arcs); the latter, the characteristics of the new mode of the locomotor cycle by affecting the functional state of the interneurons and motoneurons of the spinal generator of stepping movements.     

Metabolism of skeletal muscle proteins in experimental hypokinesia in rats

Using a radioindicator method, the metabolism of sarcoplasmic and myofibrillar proteins was studied in vivo at different stages of hypokinesia in rats. It was shown that the true muscle atrophy and the lowered content of both protein fractions during the first two weeks are due to sharp inhibition of sarcoplasmic protein biosynthesis as well as to deceleration of biosynthesis and acceleration of degradation of actomyosin. In hypokinesia the muscle mass does not increase within 3-8 weeks largely due to the acceleration of degradation of the de novo synthesized components of contractile proteins. In early hypokinesia a stressory mechanism plays an essential role in the pathogenesis of protein metabolism disturbances.     

Development of craniofacial musculature in Monodelphis domestica (marsupialia,didelphidae)

Development of craniofacial muscles of Monodelphis domestica (Marsupialia, Didelphidae) is described. In a period of 4–6 days all craniofacial muscles in M. domestica progress from myoblast condensation, to striated myofibers that are aligned in the direction of adult muscles and possess multiple, lateral nuclei. This process begins 1 to 2 days before birth and continues during the first few days after birth. Compared to other aspects of cranial development, muscle development in M. domestica is rapid. This rapid and more or less simultaneous emergence of craniofacial muscles differs from the previously described pattern of development of the cranial skeleton in marsupials, which displays a mosaic of acceleration and deceleration of regions and individual elements. Unlike the skeletal system, craniofacial muscles show no evidence of regional specialization during development. M. domestica resembles eutherian mammals in the relatively rapid and more or less simultaneous differentiation of all craniofacial muscles. It differs from eutherian taxa in that most stages of myogenesis occur postnatally, following the onset of function. The timing of the development of muscular and skeletal structures is compared and it is concluded that the relatively early development of muscle is not reflected by any particular acceleration of the differentiation or growth of skeletal structures. Finally, the difficulties in accounting for complex internal arrangements of muscles such as the tongue, given current models of myogenesis are summarized. © 1994 Wiley-Liss, Inc.     

The effect of microwaves on the bioelectric brain activity

The experiments on rats have shown that the effect of millimeter range electromagnetic radiation on the bioelectric brain activity is dependent on the initial functional state of central nervous system. Microwaves are able to cause a nonspecific electroencephalographic reaction of synchronization and probably the lower the bioelectric brain process dynamics of active rats. Enrichment of electrocorticograms with high-frequency rhythms and increase in degree of bioelectric brain dynamics can be observed in narcosis conditions. The appearance of biological resonance in the brain of narcotized rats preliminary injected aminazin by pulse-modulated microwaves is noted. This is expressed as epileptiform convulsive activity in electrocorticogram. It has been shown that the nonlinear dynamics method may provide a reliable characterization of changing bioelectric brain activity under of nonionized electromagnetic fields. It is possible to modulate the bioelectric brain activity by microwaves to change the functional state of central nervous system and probably of the whole organism.     

Immunocytochemical electron microscopic study and Western blot analysis of paramyosin in different invertebrate muscle cell types of the fruit flyDrosophila melanogaster, the earthwormEisenia foetida, and the snailHelix aspersa

Summary The presence and distribution pattern of paramyosin have been examined in different invertebrate muscle cell types by means of Western blot analysis and electron microscopy immunogold labelling. the muscles studied were: transversely striated muscle with continuous Z lines (flight muscle fromDrosophila melanogaster), transversely striated muscle with discontinuous Z lines (heart muscle from the snailHelix aspersa), obliquely striated body wall muscle from the earthwormEisenia foetida, and smooth muscles (retractor muscle from the snail and pseudoheart outer muscular layer from the earthworm). Paramyosin-like immunoreactivity was localized in thick filaments of all muscles studied. Immunogold particle density was similar along the whole thick filament length in insect flight muscle but it predominated in filament tips of fusiform thick filaments in both snail heart and earthworm body wall musculature when these filaments were observed in longitudinal sections. In obliquely sectioned thick filaments, immunolabelling was more abundant at the sites where filaments disappeared from the section. These results agree with the notion that paramyosin extended along the whole filament length, but that it can only be immunolabelled when it is not covered by myosin. In all muscles examined, immunolabelling density was lower in cross-sectioned myofilaments than in longitudinally sectioned myofilaments. This suggests that paramyosin does not form a continuous filament. The results of a semiquantitative analysis of paramyosin-like immunoreactivity indicated that it was more abundant in striated than in smooth muscles, and that, within striated muscles, transversely striated muscles contain more paramyosin than obliquely striated muscles.     

Effect of vitamin E-deficiency on the activity of some lysosomal and non-lysosomal proteases in rabbit muscles.

The activity of different cathepsins and neutral proteinases was measured in normal and vitamin E-deficient rabbit muscles using specific substrates. Among the changes of enzyme activities in dystrophy caused by vitamin E-deficiency the increase in the activity of cathepsin B is the most striking. The activity of cathepsin H, both in the fast and slow muscles and that of MMP-ase in the slow muscle remains practically unchanged. Activities of other proteases significantly increase. The change in the activity of proteolytic enzymes in striated muscle of vitamin E-deficient rabbits seems to be selective. As a rule the increase in the activity is higher in fast than in slow muscles.     

Myosin subunits and contractile properties of single fibers from hypokinetic rat muscles

The effects of prolonged hypokinesia on the contractile properties and myosin isozymes of single fibers from the synergistic fast-twitch plantaris (PL) and slow-twitch soleus (SOL) skeletal muscles of adult rats were studied after 28 days of hindlimb suspension. There was a 31% increase in the mean maximal velocity of unloaded shortening (Vmax) among fibers from SOL with no change in the mean Vmax of fibers from PL after suspension. The myosin heavy and light chain (MHC and MLC) composition of bundles and the MHC composition of single fibers from control and suspended muscles were examined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There was a marked increase in the relative amount of fast-type MHC's in hypokinetic SOL and a smaller increase in the amount of fast-type MHC's in the PL. Relatively minor changes occurred in the MLC's during hypokinesia. As Vmax increased among individual fibers from control and suspended muscles, the relative amount of fast-type MHC's increased. The results demonstrate that the myosin isozyme composition of skeletal muscle, especially the heavy chains, is altered during hypokinesia, and this finding provides an explanation for changes in Vmax of rat single muscle fibers under the same conditions.