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Sample records for fiber muscle types

  1. Muscle Fiber Types and Training.

    ERIC Educational Resources Information Center

    Karp, Jason R.

    2001-01-01

    The specific types of fibers that make up individual muscles greatly influence how people will adapt to their training programs. This paper explains the complexities of skeletal muscles, focusing on types of muscle fibers (slow-twitch and fast-twitch), recruitment of muscle fibers to perform a motor task, and determining fiber type. Implications…

  2. Composition of Muscle Fiber Types in Rat Rotator Cuff Muscles.

    PubMed

    Rui, Yongjun; Pan, Feng; Mi, Jingyi

    2016-10-01

    The rat is a suitable model to study human rotator cuff pathology owing to the similarities in morphological anatomy structure. However, few studies have reported the composition muscle fiber types of rotator cuff muscles in the rat. In this study, the myosin heavy chain (MyHC) isoforms were stained by immunofluorescence to show the muscle fiber types composition and distribution in rotator cuff muscles of the rat. It was found that rotator cuff muscles in the rat were of mixed fiber type composition. The majority of rotator cuff fibers labeled positively for MyHCII. Moreover, the rat rotator cuff muscles contained hybrid fibers. So, compared with human rotator cuff muscles composed partly of slow-twitch fibers, the majority of fast-twitch fibers in rat rotator cuff muscles should be considered when the rat model study focus on the pathological process of rotator cuff muscles after injury. Gaining greater insight into muscle fiber types in rotator cuff muscles of the rat may contribute to elucidate the mechanism of pathological change in rotator cuff muscles-related diseases. Anat Rec, 299:1397-1401, 2016. © 2016 Wiley Periodicals, Inc.

  3. Muscle fiber types composition and type identified endplate morphology of forepaw intrinsic muscles in the rat.

    PubMed

    Pan, Feng; Mi, Jing-Yi; Zhang, Yan; Pan, Xiao-Yun; Rui, Yong-Jun

    2016-06-01

    The failure to accept reinnervation is considered to be one of the reasons for the poor motor functional recovery of intrinsic hand muscles (IHMs) after nerve injury. Rat could be a suitable model to be used in simulating motor function recovery of the IHMs after nerve injury as to the similarities in function and anatomy of the muscles between human and rat. However, few studies have reported the muscle fiber types composition and endplate morphologic characteristics of intrinsic forepaw muscles (IFMs) in the rat. In this study, the myosin heavy chain isoforms and acetylcholine receptors were stained by immunofluorescence to show the muscle fiber types composition and endplates on type-identified fibers of the lumbrical muscles (LMs), interosseus muscles (IMs), abductor digiti minimi (AM) and flexor pollicis brevis (FM) in rat forepaw. The majority of IFMs fibers were labeled positively for fast-switch fiber. However, the IMs were composed of only slow-switch fiber. With the exception of the IMs, the other IFMs had a part of hybrid fibers. Two-dimensional morphological characteristics of endplates on I and IIa muscle fiber had no significant differences among the IFMs. The LMs is the most suitable IFMs of rat to stimulate reinnervation of the IHMs after nerve injury. Gaining greater insight into the muscle fiber types composition and endplate morphology in the IFMs of rat may help understand the pathological and functional changes of IFMs in rat model stimulating reinnervation of IHMs after peripheral nerve injury.

  4. Muscle fiber type diversification during exercise and regeneration.

    PubMed

    Qaisar, Rizwan; Bhaskaran, Shylesh; Van Remmen, Holly

    2016-09-01

    The plasticity of skeletal muscle can be traced down to extensive metabolic, structural and molecular remodeling at the single fiber level. Skeletal muscle is comprised of different fiber types that are the basis of muscle plasticity in response to various functional demands. Resistance and endurance exercises are two external stimuli that differ in their duration and intensity of contraction and elicit markedly different responses in muscles adaptation. Further, eccentric contractions that are associated with exercise-induced injuries, elicit varied muscle adaptation and regenerative responses. Most adaptive changes are fiber type-specific and are highly influenced by diverse structural, metabolic and functional characteristics of individual fiber types. Regulation of signaling pathways by reactive oxygen species (ROS) and oxidative stress also plays an important role in muscle fiber adaptation during exercise. This review focuses on cellular and molecular responses that regulate the adaptation of skeletal muscle to exercise and exercise-related injuries.

  5. Preferential Type II Muscle Fiber Damage From Plyometric Exercise

    PubMed Central

    Macaluso, Filippo; Isaacs, Ashwin W.; Myburgh, Kathryn H.

    2012-01-01

    Context Plyometric training has been successfully used in different sporting contexts. Studies that investigated the effect of plyometric training on muscle morphology are limited, and results are controversial with regard to which muscle fiber type is mainly affected. Objective To analyze the skeletal muscle structural and ultrastructural change induced by an acute bout of plyometric exercise to determine which type of muscle fibers is predominantly damaged. Design Descriptive laboratory study. Setting Research laboratory. Patients or Other Participants Eight healthy, untrained individuals (age = 22 ± 1 years, height = 179.2 ± 6.4 cm, weight = 78.9 ± 5.9 kg). Intervention(s) Participants completed an acute bout of plyometric exercise (10 sets of 10 squat-jumps with a 1-minute rest between sets). Main Outcome Measure(s) Blood samples were collected 9 days and immediately before and 6 hours and 1, 2, and 3 days after the acute intervention. Muscle samples were collected 9 days before and 3 days after the exercise intervention. Blood samples were analyzed for creatine kinase activity. Muscle biopsies were analyzed for damage using fluorescent and electron transmission microscopy. Results Creatine kinase activity peaked 1 day after the exercise bout (529.0 ± 317.8 U/L). Immunofluorescence revealed sarcolemmal damage in 155 of 1616 fibers analyzed. Mainly fast-twitch fibers were damaged. Within subgroups, 7.6% of type I fibers, 10.3% of type IIa fibers, and 14.3% of type IIx fibers were damaged as assessed by losses in dystrophin staining. Similar damage was prevalent in IIx and IIa fibers. Electron microscopy revealed clearly distinguishable moderate and severe sarcomere damage, with damage quantifiably predominant in type II muscle fibers of both the glycolytic and oxidative subtypes (86% and 84%, respectively, versus only 27% of slow-twitch fibers). Conclusions We provide direct evidence that a single bout of plyometric exercise affected mainly type II muscle

  6. Experimental comparisons between McKibben type artificial muscles and straight fibers type artificial muscles

    NASA Astrophysics Data System (ADS)

    Nakamura, Taro

    2007-01-01

    This paper describes experimental comparison between a conventional McKibben type artificial muscle and a straight fibers type artificial muscle developed by the authors. A wearable device and a rehabilitation robot which assists a human muscle should have characteristics similar to those of human muscle. In addition, because the wearable device and the rehabilitation robot should be light, an actuator with a high power/weight ratio is needed. At present, the McKibben type is widely used as an artificial muscle, but in fact its physical model is highly nonlinear. Further, the heat and mechanical loss of this actuator are large because of the friction caused by the expansion and contraction of the sleeve. Therefore, the authors have developed an artificial muscle tube in which high strength glass fibers have been built into the tube made from natural latex rubber. As results, experimental results demonstrated that the developed artificial muscle is more effective regarding its fundamental characteristics than that of the McKibben type; the straight fibers types of artificial muscle have more contraction ratio and power, longer lifetime than the McKibben types. And it has almost same characteristics of human muscle for isotonic and isometric that evaluate it dynamically.

  7. Functional characteristics of the rat jaw muscles: daily muscle activity and fiber type composition.

    PubMed

    Kawai, Nobuhiko; Sano, Ryota; Korfage, Joannes A M; Nakamura, Saika; Tanaka, Eiji; van Wessel, Tim; Langenbach, Geerling E J; Tanne, Kazuo

    2009-12-01

    Skeletal muscles have a heterogeneous fiber type composition, which reflects their functional demand. The daily muscle use and the percentage of slow-type fibers have been shown to be positively correlated in skeletal muscles of larger animals but for smaller animals there is no information. The examination of this relationship in adult rats was the purpose of this study. We hypothesized a positive relationship between the percentage of fatigue-resistant fibers in each muscle and its total duration of use per day. Fourteen Wistar strain male rats (410-450 g) were used. A radio-telemetric device was implanted to record muscle activity continuously from the superficial masseter, deep masseter, anterior belly of digastric and anterior temporalis muscles. The degree of daily muscle use was quantified by the total duration of muscle activity per day (duty time) exceeding specified levels of the peak activity (2, 5, 20 and 50%). The fiber type composition of the muscles was examined by the myosin heavy chain content of the fibers by means of immunohistochemical staining. At lower activity levels (exceeding 2 and 5% of the peak activity), the duty time of the anterior belly of digastric muscle was significantly (P < 0.01) longer than those of the other muscles. The anterior belly of digastric muscle also contained the highest percentage of slow-type fibers (type I fiber and hybrid fiber co-expressing myosin heavy chain I + IIA) (ca. 11%; P < 0.05). By regression analysis for all four muscles, an inter-muscular comparison showed a positive relationship between the duty time (exceeding 50% of the peak activity) and the percentage of type IIX fibers (P < 0.05), which demonstrate intermediate physiological properties relative to type IIA and IIB fibers. For the jaw muscles of adult male rats, the variations of fiber type composition and muscle use suggest that the muscle containing the largest amounts of slow-type fibers (the anterior belly of digastric muscle) is mainly

  8. Mechanical properties and fiber type composition of chronically inactive muscles

    NASA Technical Reports Server (NTRS)

    Roy, R. R.; Zhong, H.; Monti, R. J.; Vallance, K. A.; Kim, J. A.; Edgerton, V. R.

    2000-01-01

    A role for neuromuscular activity in the maintenance of skeletal muscle properties has been well established. However, the role of activity-independent factors is more difficult to evaluate. We have used the spinal cord isolation model to study the effects of chronic inactivity on the mechanical properties of the hindlimb musculature in cats and rats. This model maintains the connectivity between the motoneurons and the muscle fibers they innervate, but the muscle unit is electrically "silent". Consequently, the measured muscle properties are activity-independent and thus the advantage of using this model is that it provides a baseline level (zero activity) from which regulatory factors that affect muscle cell homeostasis can be defined. In the present paper, we will present a brief review of our findings using the spinal cord isolation model related to muscle mechanical and fiber type properties.

  9. Muscle growth and fiber type composition in hind limb muscles during postnatal development in pigs.

    PubMed

    Wank, Veit; Fischer, Martin S; Walter, Bernd; Bauer, Reinhard

    2006-01-01

    Rapid postnatal development in pigs is reflected by differentiation in skeletal muscle. This process depends on muscle function and demands, but a comprehensive overview of individual developmental characteristics of quickly growing leg muscles in pigs is still missing. This study focused on the development of 10 hind limb muscles in pigs. To determine these changes in mass, fiber type patterns and fiber diameters were analyzed 0, 2, 4, 7, 14, 28, 42, 56 and 400 days after birth. Generally, the proportion of slow fibers increased from birth to 8 weeks. Thereafter, only minor changes in muscle fiber type composition were observed. The majority of the muscles contained less then 10% slow-twitch fibers at birth, increasing to between 12 (Musculus vastus lateralis) and 38% (M. gastrocnemius medialis) in adult pigs. By contrast, postural muscles already had 20-30% slow fibers at birth, and this contribution increased up to 65% in adults (i.e. M. vastus intermedius). From birth to the 2nd week, only in slow fibers could activity of oxidative enzymes be detected. A differentiation of fast-twitch fibers into subtypes with high (comparable to type IIA) and low oxidative metabolism (equivalent to type IIB) occurred between the 2nd and 4th week of life. The ratio between type II fibers with high and low oxidative enzyme activity did not change markedly through development in any muscle, although there was a trend towards an increasing proportion of type IIA fibers in the soleus. In the majority of the muscles investigated, the fast-twitch fibers with low oxidative metabolism (IIB) obtained the largest cross-sectional area. In contrast, at birth no remarkable differences in the diameter of fast and slow fibers were found. The rapid increase in muscle mass compared to body mass reflects the high performance in meat production of the cross pig investigated.

  10. Human muscle fiber type-specific insulin signaling: impact of obesity and type 2 diabetes.

    PubMed

    Albers, Peter H; Pedersen, Andreas J T; Birk, Jesper B; Kristensen, Dorte E; Vind, Birgitte F; Baba, Otto; Nøhr, Jane; Højlund, Kurt; Wojtaszewski, Jørgen F P

    2015-02-01

    Skeletal muscle is a heterogeneous tissue composed of different fiber types. Studies suggest that insulin-mediated glucose metabolism is different between muscle fiber types. We hypothesized that differences are due to fiber type-specific expression/regulation of insulin signaling elements and/or metabolic enzymes. Pools of type I and II fibers were prepared from biopsies of the vastus lateralis muscles from lean, obese, and type 2 diabetic subjects before and after a hyperinsulinemic-euglycemic clamp. Type I fibers compared with type II fibers have higher protein levels of the insulin receptor, GLUT4, hexokinase II, glycogen synthase (GS), and pyruvate dehydrogenase-E1α (PDH-E1α) and a lower protein content of Akt2, TBC1 domain family member 4 (TBC1D4), and TBC1D1. In type I fibers compared with type II fibers, the phosphorylation response to insulin was similar (TBC1D4, TBC1D1, and GS) or decreased (Akt and PDH-E1α). Phosphorylation responses to insulin adjusted for protein level were not different between fiber types. Independently of fiber type, insulin signaling was similar (TBC1D1, GS, and PDH-E1α) or decreased (Akt and TBC1D4) in muscle from patients with type 2 diabetes compared with lean and obese subjects. We conclude that human type I muscle fibers compared with type II fibers have a higher glucose-handling capacity but a similar sensitivity for phosphoregulation by insulin.

  11. CYTOLOGICAL STUDIES OF FIBER TYPES IN SKELETAL MUSCLE

    PubMed Central

    Gauthier, Geraldine F.; Padykula, Helen A.

    1966-01-01

    A comparative investigation of the mammalian diaphragm has revealed a correlation between certain cytological aspects of red and white muscle fibers and functional activity. This skeletal muscle presents the advantage of a similar and constant function among the mammals, but its functional activity varies in a quantitative manner. Both the rate of breathing (and hence the rate of contraction of the diaphragm) and metabolic activity are known to be inversely related to body size; and this study has demonstrated a relationship between cytological characteristics of the diaphragm and body size of the animal. Small fibers rich in mitochondria (red fibers) are characteristic of small mammals, which have high metabolic activity and fast breathing rates; and large fibers with relatively low mitochondrial content predominate in large mammals, which have lower metabolic activity and slower breathing rates. In mammals with body size intermediate between these two groups (including the laboratory rat), the diaphragm consists of varying mixtures of fiber types. In general, the mitochondrial content of diaphragm fibers is inversely related to body size. It appears, then, that the red fiber reflects a high degree of metabolic activity or a relatively high rate of contraction within the range exhibited by this muscle. PMID:5950272

  12. Human Masseter Muscle Fiber Type Properties, Skeletal Malocclusions, and Muscle Growth Factor Expression

    PubMed Central

    Sciote, James Joseph; Horton, Michael J.; Rowlerson, Anthea M.; Ferri, Joel; Close, John M.; Raoul, Gwenael

    2013-01-01

    Purpose We identified masseter muscle fiber type property differences in subjects with dentofacial deformities. Patients and Methods Samples of masseter muscle were collected from 139 young adults during mandibular osteotomy procedures to assess mean fiber areas and percent tissue occupancies for the 4 fiber types that comprise the muscle. Subjects were classified into 1 of 6 malocclusion groups based on the presence of a skeletal Class II or III sagittal dimension malocclusion and either a skeletal open, deep, or normal bite vertical dimension malocclusion. In a subpopulation, relative quantities of the muscle growth factors IGF-I and GDF-8 gene expression were quantified by real-time polymerase chain reaction. Results Fiber properties were not different in the sagittal malocclusion groups, but were very different in the vertical malocclusion groups (P ≤ .0004). There were significant mean fiber area differences for type II (P ≤ .0004) and type neonatal—atrial (P = .001) fiber types and for fiber percent occupancy differences for both type I–II hybrid fibers and type II fibers (P ≤ .0004). Growth factor expression differed by gender for IGF-I (P = .02) and GDF-8 (P < .01). The ratio of IGF-I:GDF-8 expression associates with type I and II mean fiber areas. Conclusion Fiber type properties are very closely associated with variations in vertical growth of the face, with statistical significance for overall comparisons at P ≤ .0004. An increase in masseter muscle type II fiber mean fiber areas and percent tissue occupancies is inversely related to increases in vertical facial dimension. PMID:21821327

  13. MOUSE TRANSGENIC LINES THAT SELECTIVELY LABEL TYPE I, TYPE IIA AND TYPES IIX+B SKELETAL MUSCLE FIBERS

    PubMed Central

    Chakkalakal, Joe V.; Kuang, Shihuan; Buffelli, Mario; Lichtman, Jeff W.; Sanes, Joshua R.

    2014-01-01

    Skeletal muscle fibers vary in contractile and metabolic properties. Four main fiber types are present in mammalian trunk and limb muscles; they are called I, IIA, IIX and IIB, ranging from slowest- to fastest-contracting. Individual muscles contain stereotyped proportions of two or more fiber types. Fiber type is determined by a combination of nerve-dependent and –independent influences, leading to formation of “homogeneous motor units” in which all branches of a single motor neuron form synapses on fibers of a single type. Fiber type composition of muscles can be altered in adulthood by multiple factors including exercise, denervation, hormones and aging. To facilitate analysis of muscle development, plasticity and innervation, we generated transgenic mouse lines in which Type I, Type IIA, and Type IIX+B fibers can be selectively labeled with distinguishable fluorophores. We demonstrate their use for motor unit reconstruction and live imaging of nerve-dependent alterations in fiber type. PMID:21898764

  14. Postnatal development of fiber type composition in rabbit jaw and leg muscles.

    PubMed

    Korfage, J A M; Helmers, R; Matignon, M de Goüyon; van Wessel, T; Langenbach, G E J; van Eijden, T M G J

    2009-01-01

    We examined the difference in fiber type composition and cross-sectional areas during postnatal development in male rabbit jaw muscles and compared these with changes in leg muscles. The myosin heavy chain (MyHC) content of the fibers was determined by immunohistochemistry. No fiber type difference was found between the jaw muscles in 20-week-old rabbits. However, the way this adult fiber type composition was reached differed between the muscles. The deep temporalis, medial pterygoid, and superficial masseter displayed an increase in alpha fibers during early and a decrease during late postnatal development. Other jaw muscles displayed an increase in alpha fibers during early development only. In contrast, alpha fibers were not found in the soleus, in which fiber type changes were completed at week 4. The gastrocnemius muscle did not change its fiber type composition. Initially, fibers in jaw-opening muscles had larger cross-sectional areas than in other muscles, but they increased less during development. Although there were no large differences in the fiber type composition of muscles in young adult rabbits, large differences were found in the jaw muscles, but not in the leg muscles, during development. In part, these developmental changes in fiber percentages within the jaw muscles can be explained by functional modifications in this muscle group. In the present study, the deep temporalis, medial pterygoid, and superficial masseter showed the most dramatic percent changes in fibers during postnatal development.

  15. Comparisons of different muscle metabolic enzymes and muscle fiber types in Jinhua and Landrace pigs.

    PubMed

    Guo, J; Shan, T; Wu, T; Zhu, L N; Ren, Y; An, S; Wang, Y

    2011-01-01

    Western and indigenous Chinese pig breeds show obvious differences in muscle growth and meat quality, however, the underlying molecular mechanism remains unclear. The main objective of this study was to evaluate the breed-specific mechanisms controlling meat quality and postmortem muscle metabolism. The specific purpose was to investigate the variations in meat quality, muscle fiber type, and enzyme activity between local Jinhua and exotic Landrace pigs at the same age (180 d of age), as well as the same BW of 64 kg, respectively. We compared differentially expressed muscle fiber types such as types I and IIa (oxidative), type IIb (glycolytic), as well as type IIx (intermediate) fibers in LM and soleus muscles of Jinhua and Landrace pigs using real-time reverse-transcription PCR. Furthermore, the metabolic enzyme activities of lactate dehydrogenase, as well as succinic dehydrogenase and malate dehydrogenase, were used as markers of glycolytic and oxidative capacities, respectively. Results showed that Jinhua pigs exhibited greater intramuscular fat content and less drip loss compared with the Landrace (P < 0.01). Meanwhile, the mRNA abundance of oxidative and intermediate fibers was increased in Jinhua pigs, whereas the glycolytic fibers were more highly expressed in the Landrace (P < 0.01). In addition, Jinhua pigs possessed greater oxidative capacity than that of the Landrace (P < 0.05). These results suggested that the increased expression of the oxidative and intermediate fibers and greater activities of oxidative enzymes in Jinhua pigs were related to meat quality as indicated by a greater intramuscular fat and reduced drip loss. Based on these results, we conclude that muscle fiber composition and postmortem muscle metabolism can explain, in part, the variation of meat quality in Jinhua and Landrace pigs. These results may provide valuable information for understanding the molecular mechanism responsible for breed specific differences in growth performance

  16. Fiber type characterization of striated muscles related to micturition in female rabbits.

    PubMed

    López-García, Kenia; Mariscal-Tovar, Silvia; Martínez-Gómez, Margarita; Jiménez-Estrada, Ismael; Castelán, Francisco

    2014-04-01

    Pelvic and perineal striated muscles are relevant for reproduction and micturition in female mammals. Damage to these muscles is associated with pelvic organ prolapse and stress urinary incontinence. The fiber type composition of skeletal muscle influences the susceptibility for damage and/or regeneration. The aim of the present study was to determine the fiber type composition of a perineal muscle, the bulbospongiosus, and a pelvic muscle, the pubococcygeus. Both muscles were harvested from adult female rabbits (8-10 months old). NADH-TR (nicotinamide adenine dinucleotide tetrazolium reductase) histochemistry was undertaken to identify oxidative and glycolytic muscle fibers. Alkaline (pH 9.4) ATP-ase (actomyosin adenosine triphosphatase) histochemistry was used to classify type I, type IIb or type IIa/IId muscle fibers. Results showed that the content of glycolytic fibers in the bulbospongiosus muscle was higher than that of oxidative fibers. Meanwhile, the opposite was true for the pubococcygeus. In the bulbospongiosus muscle, the content of type IIb muscle fibers was higher than that of type I, but was similar to that of type IIa/IId. In contrast, the content of each fiber type was similar in the pubococcygeus muscle. The relative proportion of fibers in bulbospongiosus and pubococcygeus muscles is consistent with their function during voiding and storage phases of micturition.

  17. Muscle fiber type specific induction of slow myosin heavy chain 2 gene expression by electrical stimulation

    SciTech Connect

    Crew, Jennifer R.; Falzari, Kanakeshwari; DiMario, Joseph X.

    2010-04-01

    Vertebrate skeletal muscle fiber types are defined by a broad array of differentially expressed contractile and metabolic protein genes. The mechanisms that establish and maintain these different fiber types vary throughout development and with changing functional demand. Chicken skeletal muscle fibers can be generally categorized as fast and fast/slow based on expression of the slow myosin heavy chain 2 (MyHC2) gene in fast/slow muscle fibers. To investigate the cellular and molecular mechanisms that control fiber type formation in secondary or fetal muscle fibers, myoblasts from the fast pectoralis major (PM) and fast/slow medial adductor (MA) muscles were isolated, allowed to differentiate in vitro, and electrically stimulated. MA muscle fibers were induced to express the slow MyHC2 gene by electrical stimulation, whereas PM muscle fibers did not express the slow MyHC2 gene under identical stimulation conditions. However, PM muscle fibers did express the slow MyHC2 gene when electrical stimulation was combined with inhibition of inositol triphosphate receptor (IP3R) activity. Electrical stimulation was sufficient to increase nuclear localization of expressed nuclear-factor-of-activated-T-cells (NFAT), NFAT-mediated transcription, and slow MyHC2 promoter activity in MA muscle fibers. In contrast, both electrical stimulation and inhibitors of IP3R activity were required for these effects in PM muscle fibers. Electrical stimulation also increased levels of peroxisome-proliferator-activated receptor-{gamma} co-activator-1 (PGC-1{alpha}) protein in PM and MA muscle fibers. These results indicate that MA muscle fibers can be induced by electrical stimulation to express the slow MyHC2 gene and that fast PM muscle fibers are refractory to stimulation-induced slow MyHC2 gene expression due to fast PM muscle fiber specific cellular mechanisms involving IP3R activity.

  18. Myosin types and fiber types in cardiac muscle. I. Ventricular myocardium

    PubMed Central

    1981-01-01

    Antisera against bovine atrial myosin were raised in rabbits, purified by affinity chromatography, and absorbed with insolubilized ventricular myosin. Specific anti-bovine atrial myosin (anti-bAm) antibodies reacted selectively with atrial myosin heavy chains, as determined by enzyme immunoassay combined with SDS-gel electrophoresis. In direct and indirect immunofluorescence assay, anti-bAm was found to stain all atrial muscle fibers and a minor proportion of ventricular muscle fibers in the right ventricle of the bovine heart. In contrast, almost all muscle fibers in the left ventricle were unreactive. Purkinje fibers showed variable reactivity. In the rabbit heart, all atrial muscle fibers were stained by anti-bAm, whereas ventricular fibers showed a variable response in both the right and left ventricle, with a tendency for reactive fibers to be more numerous in the right ventricle and in subepicardial regions. Diversification of fiber types with respect to anti-bAm reactivity was found to occur during late stages of postnatal development in the rabbit heart and to be influenced by thyroid hormone. All ventricular muscle fibers became strongly reactive after thyroxine treatment, whereas they became unreactive or poorly reactive after propylthiouracil treatment. These findings are consistent with the existence of different ventricular isomyosins whose relative proportions can vary according to the thyroid state. Variations in ventricular isomyosin composition can account for the changes in myosin Ca2+-activated ATPase activity previously observed in cardiac muscle from hyper- and hypothyroid animals and may be responsible for the changes in the velocity of contraction of ventricular myocardium that occur under these conditions. The differential distribution of ventricular isomyosins in the normal heart suggests that fiber types with different contractile properties may coexist in the ventricular myocardium. PMID:7009623

  19. A comparative study of the membrane structure in different types of muscle fibers in the frog.

    PubMed

    Verma, V

    1984-09-01

    The muscle membrane of slow and fast fibers in cruralis and iliofibularis muscles and of intermediate fibers in submaxillaris muscle of the frog is studied in freeze-fracture replicas. A comparison of membrane folds, number, size and distribution of caveolae and of intramembrane particles (IMP) is given. In slow muscle fibers, the membrane folds are systematically present at the level of the I zone with a transversal continuity, whereas in fast and intermediate types the membrane folds are small and are randomly distributed. In slow muscle the caveolae are more numerous at the I zone than in the part corresponding to the center of the sarcomere. In fast muscle, small groups of caveolae form linear patterns, and in intermediate fibers the distribution is random. The number of caveolae in slow muscle fibers is two times more than in fast and intermediate fibers. The mean area of caveolae opening is largest in fast and smallest in slow muscle fibers. The number of IMP is significantly different in the three types of fibers, being highest in slow and lowest in intermediate fibers. The different pattern of folds in slow fibers may correspond to the different contractile properties of this fiber type. The presence of double the number of caveolae in slow fibers correlated to the less elaborate T system in this fiber type shows the possibility that slow fibers may be the result of an arrest during development for the performance of a different function. The difference in IMP density in the three muscle fiber types may be interpreted as the difference in their electrical properties.

  20. Fiber-type composition of hindlimb muscles in the turtle, Pseudemys (Trachemys) scripta elegans.

    PubMed

    Laidlaw, D H; Callister, R J; Stuart, D G

    1995-08-01

    A description is provided of the fiber-type composition of several hindlimb muscles of the adult turtle, Pseudemys (Trachemys) scripta elegans. In addition, cross-section areas of each fiber type and an estimation of the relative (weighted) cross-section area (wCSA) occupied by the different fiber types are also provided. Seven muscles were selected for study, based on their suitability for future neurophysiological analysis as components of the segmental motor system, and on their homologies with muscles in other vertebrates. The test muscles were iliofibularis (ILF), ambiens (AMB), external gastrocnemius (EG), extensor digitorum communis (EDC), flexor digitorum longus (FDL), tibialis anterior (TA), and peroneus anterior (PA). Serial sections of these muscles were stained for myosin adenosine triphosphatase (ATPase), NADH-diaphorase, and alpha-glycerophosphate dehydrogenase (alpha-GPDH), thereby enabling fiber-type classification on the basis of indirect markers for contraction speed and oxidative (aerobic) vs. glycolytic (anaerobic) metabolism. All muscles contained three fiber types: slow oxidative (SO; possibly including some non-twitch tonic fibers); fast oxidative glycolytic (FOG); and fast glycolytic (Fg). There were at least 30% FOG and 50% FOG + Fg fibers in the seven muscles, the extreme distributions being the predominantly glycolytic ILF vs. the predominantly oxidative FDL muscle (ILF--15.5% SO, 35.2% FOG, 49.3% Fg vs. FDL--49.1% SO, 41.1% FOG, 9.8% Fg). As in other species, the test muscles exhibited varying degrees of regional concentration (compartmentalization) of the different fiber types. This feature was most striking in ILF. Pronounced compartmentalization was also observed in AMB, EG, PA, TA, and EDC, whereas the distribution of fiber types in the highly oxidative FDL was homogeneous. In five of the seven muscles, fiber size was ranked with Fg > FOG > SO. In terms of wCSA, which provides a coarse-grain measure of the different fiber types

  1. Changes in skeletal muscle biochemistry and histology relative to fiber type in rats with heart failure

    NASA Technical Reports Server (NTRS)

    Delp, M. D.; Duan, C.; Mattson, J. P.; Musch, T. I.

    1997-01-01

    One of the primary consequences of left ventricular dysfunction (LVD) after myocardial infarction is a decrement in exercise capacity. Several factors have been hypothesized to account for this decrement, including alterations in skeletal muscle metabolism and aerobic capacity. The purpose of this study was to determine whether LVD-induced alterations in skeletal muscle enzyme activities, fiber composition, and fiber size are 1) generalized in muscles or specific to muscles composed primarily of a given fiber type and 2) related to the severity of the LVD. Female Wistar rats were divided into three groups: sham-operated controls (n = 13) and rats with moderate (n = 10) and severe (n = 7) LVD. LVD was surgically induced by ligating the left main coronary artery and resulted in elevations (P < 0.05) in left ventricular end-diastolic pressure (sham, 5 +/- 1 mmHg; moderate LVD, 11 +/- 1 mmHg; severe LVD, 25 +/- 1 mmHg). Moderate LVD decreased the activities of phosphofructokinase (PFK) and citrate synthase in one muscle composed of type IIB fibers but did not modify fiber composition or size of any muscle studied. However, severe LVD diminished the activity of enzymes involved in terminal and beta-oxidation in muscles composed primarily of type I fibers, type IIA fibers, and type IIB fibers. In addition, severe LVD induced a reduction in the activity of PFK in type IIB muscle, a 10% reduction in the percentage of type IID/X fibers, and a corresponding increase in the portion of type IIB fibers. Atrophy of type I fibers, type IIA fibers, and/or type IIB fibers occurred in soleus and plantaris muscles of rats with severe LVD. These data indicate that rats with severe LVD after myocardial infarction exhibit 1) decrements in mitochondrial enzyme activities independent of muscle fiber composition, 2) a reduction in PFK activity in type IIB muscle, 3) transformation of type IID/X to type IIB fibers, and 4) atrophy of type I, IIA, and IIB fibers.

  2. Fiber-type differences in masseter muscle associated with different facial morphologies

    PubMed Central

    Rowlerson, Anthea; Raoul, Gwénaël; Daniel, Yousif; Close, John; Maurage, Claude-Alain; Ferri, Joel; Sciote, James J.

    2013-01-01

    Background The influence of muscle forces and associated physiologic behaviors on dental and skeletal development is well recognized but difficult to quantify because of the limited understanding of the interrelationships between physiologic and other mechanisms during growth. Methods The purpose of this study was to characterize fiber-type composition of masseter muscle in 44 subjects during surgical correction of malocclusion. Four fiber types were identified after immunostaining of biopsy sections with myosin heavy chain-specific antibodies, and the average fiber diameter and percentage of muscle occupancy of the fiber types were determined in each of 6 subject groups (Class II or Class III and open bite, normal bite, or deepbite). A 2 × 3 × 4 analysis of variance was used to determine significant differences between mean areas for fiber types, vertical relationships, and sagittal relationships. Results There were significant differences in percentage of occupancy of fiber types in masseter muscle in bite groups with different vertical dimensions. Type I fiber occupancy increased in open bites, and conversely, type II fiber occupancy increased in deepbites. The association between sagittal jaw relationships and mean fiber area was less strong, but, in the Class III group, the average fiber area was significantly different between the open bite, normal bite, and deepbite subjects. In the Class III subjects, type I and I/II hybrid fiber areas were greatly increased in subjects with deepbite. Conclusions Given the variation between subjects in fiber areas and fiber numbers, larger subject populations will be needed to demonstrate more significant associations between sagittal relationships and muscle composition. However, the robust influence of jaw-closing muscles on vertical dimension allowed us to conclude that vertical bite characteristics vary according to the fiber type composition of masseter muscle. PMID:15643413

  3. Fiber type composition and maximum shortening velocity of muscles crossing the human shoulder.

    PubMed

    Srinivasan, R C; Lungren, M P; Langenderfer, J E; Hughes, R E

    2007-03-01

    A study of the fiber type composition of fourteen muscles spanning the human glenohumeral joint was carried out with the purpose of determining the contribution of fiber types to overall muscle cross-sectional area (CSA) and to estimate the maximum shortening velocity (V(max)) of those muscles. Muscle biopsies were procured from 4 male cadavers (mean age 50) within 24 hr of death, snap frozen, mounted, and transversely sectioned (10 microm). Slides were stained for myofibrillar ATPase after alkaline preincubation. Photoimages were taken of defined areas (100 fibers) using the Bioquant system, and fiber type and CSA were measured from these images. Staining for mATPase produced three different fiber types: slow-oxidative (SO), fast-oxidative-glycolytic (FOG), and fast-glycolytic (FG). On average, the muscle fiber type composition ranged from 22 to 40% of FG, from 17 to 51% of FOG, and from 23 to 56% of SO. Twelve out of the 14 muscles had average SO proportions ranging from 35 to 50%. V(max) was calculated from the fiber type contribution relative to CSA and shortening velocity values taken from the literature. The maximum velocities of shortening presented here provide a physiological basis for the development of human shoulder musculoskeletal models suitable for predicting muscle forces for functionally relevant tasks encompassing conditions of muscle shortening and lengthening.

  4. Fiber type effects on contraction-stimulated glucose uptake and GLUT4 abundance in single fibers from rat skeletal muscle.

    PubMed

    Castorena, Carlos M; Arias, Edward B; Sharma, Naveen; Bogan, Jonathan S; Cartee, Gregory D

    2015-02-01

    To fully understand skeletal muscle at the cellular level, it is essential to evaluate single muscle fibers. Accordingly, the major goals of this study were to determine if there are fiber type-related differences in single fibers from rat skeletal muscle for: 1) contraction-stimulated glucose uptake and/or 2) the abundance of GLUT4 and other metabolically relevant proteins. Paired epitrochlearis muscles isolated from Wistar rats were either electrically stimulated to contract (E-Stim) or remained resting (No E-Stim). Single fibers isolated from muscles incubated with 2-deoxy-d-[(3)H]glucose (2-DG) were used to determine fiber type [myosin heavy chain (MHC) isoform protein expression], 2-DG uptake, and abundance of metabolically relevant proteins, including the GLUT4 glucose transporter. E-Stim, relative to No E-Stim, fibers had greater (P < 0.05) 2-DG uptake for each of the isolated fiber types (MHC-IIa, MHC-IIax, MHC-IIx, MHC-IIxb, and MHC-IIb). However, 2-DG uptake for E-Stim fibers was not significantly different among these five fiber types. GLUT4, tethering protein containing a UBX domain for GLUT4 (TUG), cytochrome c oxidase IV (COX IV), and filamin C protein levels were significantly greater (P < 0.05) in MHC-IIa vs. MHC-IIx, MHC-IIxb, or MHC-IIb fibers. TUG and COX IV in either MHC-IIax or MHC-IIx fibers exceeded values for MHC-IIxb or MHC-IIb fibers. GLUT4 levels for MHC-IIax fibers exceeded MHC-IIxb fibers. GLUT4, COX IV, filamin C, and TUG abundance in single fibers was significantly (P < 0.05) correlated with each other. Differences in GLUT4 abundance among the fiber types were not accompanied by significant differences in contraction-stimulated glucose uptake.

  5. Myosin types and fiber types in cardiac muscle. II. Atrial myocardium

    PubMed Central

    1982-01-01

    Antibodies were produced against myosins isolated from the left atrial myocardium (anti-bAm) and the left ventricular myocardium (anti-bVm) of the bovine heart. Cross-reactive antibodies were removed by cross- absorption. Absorbed anti-bAm and anti-bVm were specific for the myosin heavy chains when tested by enzyme immunoassay combined with SDS gel electrophoresis. Indirect immunofluorescence was used to determine the reactivity of atrial muscle fibers to the two antibodies. Three populations of atrial muscle fibers were distinguished in the bovine heart: (a) fibers reactive with anti-bAm and unreactive with anti-bVm, like most fibers in the left atrium; (b) fibers reactive with both antibodies, especially numerous in the right atrium; (c) fibers reactive with anti-bVm and unreactive with anti-bAm, present only in the interatrial septum and in specific regions of the right atrium, such as the crista terminalis. These findings can be accounted for by postulating the existence of two distinct types of atrial myosin heavy chains, one of which is antigenically related to ventricular myosin. The tendency for fibers labeled by anti-bVm to occur frequently in bundles and their preferential distribution in the crista terminalis, namely along one of the main conduction pathways between the sinus node and the atrioventricular node, and in the interatrial septum, where different internodal tracts are known to converge, suggests that these fibers may be specialized for faster conduction. PMID:6218175

  6. Mitochondrial Dynamics is a Distinguishing Feature of Skeletal Muscle Fiber Types and Regulates Organellar Compartmentalization.

    PubMed

    Mishra, Prashant; Varuzhanyan, Grigor; Pham, Anh H; Chan, David C

    2015-12-01

    Skeletal muscle fibers differentiate into specific fiber types with distinct metabolic properties determined by their reliance on oxidative phosphorylation (OXPHOS). Using in vivo approaches, we find that OXPHOS-dependent fibers, compared to glycolytic fibers, contain elongated mitochondrial networks with higher fusion rates that are dependent on the mitofusins Mfn1 and Mfn2. Switching of a glycolytic fiber to an oxidative IIA type is associated with elongation of mitochondria, suggesting that mitochondrial fusion is linked to metabolic state. Furthermore, we reveal that mitochondrial proteins are compartmentalized to discrete domains centered around their nuclei of origin. The domain dimensions are dependent on fiber type and are regulated by the mitochondrial dynamics proteins Mfn1, Mfn2, and Mff. Our results indicate that mitochondrial dynamics is tailored to fiber type physiology and provides a rationale for the segmental defects characteristic of aged and diseased muscle fibers.

  7. Contractile properties of rat, rhesus monkey, and human type I muscle fibers

    NASA Technical Reports Server (NTRS)

    Widrick, J. J.; Romatowski, J. G.; Karhanek, M.; Fitts, R. H.

    1997-01-01

    It is well known that skeletal muscle intrinsic maximal shortening velocity is inversely related to species body mass. However, there is uncertainty regarding the relationship between the contractile properties of muscle fibers obtained from commonly studied laboratory animals and those obtained from humans. In this study we determined the contractile properties of single chemically skinned fibers prepared from rat, rhesus monkey, and human soleus and gastrocnemius muscle samples under identical experimental conditions. All fibers used for analysis expressed type I myosin heavy chain as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Allometric coefficients for type I fibers from each muscle indicated that there was little change in peak tension (force/fiber cross-sectional area) across species. In contrast, both soleus and gastrocnemius type I fiber maximal unloaded shortening velocity (Vo), the y-intercept of the force-velocity relationship (Vmax), peak power per unit fiber length, and peak power normalized for fiber length and cross-sectional area were all inversely related to species body mass. The present allometric coefficients for soleus fiber Vo (-0.18) and Vmax (-0.11) are in good agreement with published values for soleus fibers obtained from common laboratory and domesticated mammals. Taken together, these observations suggest that the Vo of slow fibers from quadrupeds and humans scale similarly and can be described by the same quantitative relationships. These findings have implications in the design and interpretation of experiments, especially those that use small laboratory mammals as a model of human muscle function.

  8. Skeletal muscle fiber types in the ghost crab, Ocypode quadrata: implications for running performance.

    PubMed

    Perry, Michael J; Tait, Jennifer; Hu, John; White, Scott C; Medler, Scott

    2009-03-01

    Ghost crabs possess rapid running capabilities, which make them good candidates for comparing invertebrate exercise physiology with that of more extensively studied vertebrates. While a number of studies have examined various aspects of running physiology and biomechanics in terrestrial crabs, none to date have defined the basic skeletal muscle fiber types that power locomotion. In the current study, we investigated skeletal muscle fiber types comprising the extensor and flexor carpopodite muscles in relation to running performance in the ghost crab. We used kinematic analyses to determine stride frequency and muscle shortening velocity and found that both parameters are similar to those of comparably sized mammals but slower than those observed in running lizards. Using several complementary methods, we found that the muscles are divided into two primary fiber types: those of the proximal and distal regions possess long sarcomeres (6.2+/-2.3 microm) observed in crustacean slow fibers and have characteristics of aerobic fibers whereas those of the muscle mid-region have short sarcomeres (3.5+/-0.4 microm) characteristic of fast fibers and appear to be glycolytic. Each fiber type is characterized by several different myofibrillar protein isoforms including multiple isoforms of myosin heavy chain (MHC), troponin I (TnI), troponin T (TnT) and a crustacean fast muscle protein, P75. Three different isoforms of MHC are differentially expressed in the muscles, with fibers of the mid-region always co-expressing two isoforms at a 1:1 ratio within single fibers. Based on our analyses, we propose that these muscles are functionally divided into a two-geared system, with the aerobic fibers used for slow sustained activities and the glycolytic mid-region fibers being reserved for explosive sprints. Finally, we identified subtle differences in myofibrillar isoform expression correlated with crab body size, which changes by several orders of magnitude during an animal's lifetime.

  9. Fiber type composition of the sternomastoid and diaphragm muscles of dystrophin-deficient mdx mice.

    PubMed

    Guido, Anderson Neri; Campos, Gerson Eduardo Rocha; Neto, Humberto Santo; Marques, Maria Julia; Minatel, Elaine

    2010-10-01

    The muscle fiber phenotype is mainly determined by motoneuron innervation and changes in neuromuscular interaction alter the muscle fiber type. In dystrophin-deficient mdx mice, changes in the molecular assembly of the neuromuscular junction and in nerve terminal sprouting occur in the sternomastoid (STN) muscle during early stages of the disease. In this study, we were interested to see whether early changes in neuromuscular assembly are correlated with alterations in fiber type in dystrophic STN at 2 months of age. A predominance of hybrid fast myofibers (about 52% type IIDB) was observed in control (C57Bl/10) STN. In mdx muscle, the lack of dystrophin did not change this profile (about 54% hybrid type IIDB). Pure fast type IID fibers predominated in normal and dystrophic diaphragm (DIA; about 39% in control and 30% in mdx muscle) and a population of slow Type I fibers was also present (about 10% in control and 13% in mdx muscle). In conclusion, early changes in neuromuscular assembly do not affect the fiber type composition of dystrophic STN. In contrast to the pure fast fibers of the more affected DIA, the hybrid phenotype of the STN may permit dynamic adaptations during progression of the disease.

  10. Muscle fiber type distribution in climbing Hawaiian gobioid fishes: ontogeny and correlations with locomotor performance.

    PubMed

    Cediel, Roberto A; Blob, Richard W; Schrank, Gordon D; Plourde, Robert C; Schoenfuss, Heiko L

    2008-01-01

    Three species of Hawaiian amphidromous gobioid fishes are remarkable in their ability to climb waterfalls up to several hundred meters tall. Juvenile Lentipes concolor and Awaous guamensis climb using rapid bursts of axial undulation, whereas juvenile Sicyopterus stimpsoni climb using much slower movements, alternately attaching oral and pelvic sucking disks to the substrate during prolonged bouts of several cycles. Based on these differing climbing styles, we hypothesized that propulsive musculature in juvenile L. concolor and A. guamensis would be dominated by white muscle fibers, whereas S. stimpsoni would exhibit a greater proportion of red muscle fibers than other climbing species. We further predicted that, because adults of these species shift from climbing to burst swimming as their main locomotor behavior, muscle from adult fish of all three species would be dominated by white fibers. To test these hypotheses, we used ATPase assays to evaluate muscle fiber type distribution in Hawaiian climbing gobies for three anatomical regions (midbody, anal, and tail). Axial musculature was dominated by white muscle fibers in juveniles of all three species, but juvenile S. stimpsoni had a significantly greater proportion of red fibers than the other two species. Fiber type proportions of adult fishes did not differ significantly from those of juveniles. Thus, muscle fiber type proportions in juveniles appear to help accommodate differences in locomotor demands among these species, indicating that they overcome the common challenge of waterfall climbing through both diverse behaviors and physiological specializations.

  11. Fnip1 regulates skeletal muscle fiber type specification, fatigue resistance, and susceptibility to muscular dystrophy.

    PubMed

    Reyes, Nicholas L; Banks, Glen B; Tsang, Mark; Margineantu, Daciana; Gu, Haiwei; Djukovic, Danijel; Chan, Jacky; Torres, Michelle; Liggitt, H Denny; Hirenallur-S, Dinesh K; Hockenbery, David M; Raftery, Daniel; Iritani, Brian M

    2015-01-13

    Mammalian skeletal muscle is broadly characterized by the presence of two distinct categories of muscle fibers called type I "red" slow twitch and type II "white" fast twitch, which display marked differences in contraction strength, metabolic strategies, and susceptibility to fatigue. The relative representation of each fiber type can have major influences on susceptibility to obesity, diabetes, and muscular dystrophies. However, the molecular factors controlling fiber type specification remain incompletely defined. In this study, we describe the control of fiber type specification and susceptibility to metabolic disease by folliculin interacting protein-1 (Fnip1). Using Fnip1 null mice, we found that loss of Fnip1 increased the representation of type I fibers characterized by increased myoglobin, slow twitch markers [myosin heavy chain 7 (MyH7), succinate dehydrogenase, troponin I 1, troponin C1, troponin T1], capillary density, and mitochondria number. Cultured Fnip1-null muscle fibers had higher oxidative capacity, and isolated Fnip1-null skeletal muscles were more resistant to postcontraction fatigue relative to WT skeletal muscles. Biochemical analyses revealed increased activation of the metabolic sensor AMP kinase (AMPK), and increased expression of the AMPK-target and transcriptional coactivator PGC1α in Fnip1 null skeletal muscle. Genetic disruption of PGC1α rescued normal levels of type I fiber markers MyH7 and myoglobin in Fnip1-null mice. Remarkably, loss of Fnip1 profoundly mitigated muscle damage in a murine model of Duchenne muscular dystrophy. These results indicate that Fnip1 controls skeletal muscle fiber type specification and warrant further study to determine whether inhibition of Fnip1 has therapeutic potential in muscular dystrophy diseases.

  12. Effects of muscle fiber type and size on EMG median frequency and conduction velocity.

    PubMed

    Kupa, E J; Roy, S H; Kandarian, S C; De Luca, C J

    1995-07-01

    This paper describes an in vitro method for comparing surface-detected electromyographic median frequency (MF) and conduction velocity (CV) parameters with histochemical measurements of muscle fiber type composition and cross-sectional area (CSA). Electromyographic signals were recorded during electrically elicited tetanic contractions from rat soleus, extensor digitorum longus, and diaphragm muscles placed in an oxygenated Krebs bath. Fibers were typed as slow oxidative, fast oxidative glycolytic, and fast glycolytic based on histochemical enzyme stains. Muscles with a greater percentage of fast glycolytic and fast oxidative glycolytic fibers exhibited greater initial values of MF and CV as well as a greater reduction in these variables over the course of the contraction. Regression indicated that fiber type composition could be predicted based on two MF parameters. A weighted measure of muscle fiber CSA was found to be linearly related to both initial MF and CV. The results of this study suggest that MF and CV parameters recorded during a muscular contraction are related to muscle fiber type composition and muscle fiber CSA.

  13. A One-Step Immunostaining Method to Visualize Rodent Muscle Fiber Type within a Single Specimen

    PubMed Central

    Sawano, Shoko; Komiya, Yusuke; Ichitsubo, Riho; Ohkawa, Yasuyuki; Nakamura, Mako; Tatsumi, Ryuichi; Ikeuchi, Yoshihide; Mizunoya, Wataru

    2016-01-01

    In this study, we present a quadruple immunostaining method for rapid muscle fiber typing of mice and rats using antibodies specific to the adult myosin heavy chain (MyHC) isoforms MyHC1, 2A, 2X, and 2B, which are common marker proteins of distinct muscle fiber types. We developed rat monoclonal antibodies specific to each MyHC isoform and conjugated these four antibodies to fluorophores with distinct excitation and emission wavelengths. By mixing the four types of conjugated antibodies, MyHC1, 2A, 2X, and 2B could be distinguished within a single specimen allowing for facile delineation of skeletal muscle fiber types. Furthermore, we could observe hybrid fibers expressing MyHC2X and MyHC2B together in single longitudinal muscle sections from mice and rats, that was not attained in previous techniques. This staining method is expected to be applied to study muscle fiber type transition in response to environmental factors, and to ultimately develop techniques to regulate animal muscle fiber types. PMID:27814384

  14. Catalase-positive microperoxisomes in rat soleus and extensor digitorum longus muscle fiber types

    NASA Technical Reports Server (NTRS)

    Riley, Danny A.; Bain, James L. W.; Ellis, Stanley

    1988-01-01

    The size, distribution, and content of catalase-reactive microperoxisomes were investigated cytochemically in three types of muscle fibers from the soleus and the extensor digitorum longus (EDL) of male rats. Muscle fibers were classified on the basis of the mitochondrial content and distribution, the Z-band widths, and the size and shape of myofibrils as the slow-twitch oxidative (SO), the fast-twitch oxidative glycolytic (FOG), and the fast-twitch glycolytic (FG) fibers. It was found that both the EDL and soleus SO fibers possessed the largest microperoxisomes. A comparison of microperoxisome number per muscle fiber area or the microperoxisome area per fiber area revealed following ranking, starting from the largest number and the area-ratio values: soleus SO, EDL SO, EDL FOG, and EDL FG.

  15. Effects of fiber type on force depression after active shortening in skeletal muscle.

    PubMed

    Joumaa, V; Power, G A; Hisey, B; Caicedo, A; Stutz, J; Herzog, W

    2015-07-16

    The aim of this study was to investigate force depression in Type I and Type II muscle fibers. Experiments were performed using skinned fibers from rabbit soleus and psoas muscles. Force depression was quantified after active fiber shortening from an average sarcomere length (SL) of 3.2µ m to an average SL of 2.6 µm at an absolute speed of 0.115f iber length/s and at a relative speed corresponding to 17% of the unloaded shortening velocity (V0) in each type of fibers. Force decay and mechanical work during shortening were also compared between fiber types. After mechanical testing, each fiber was subjected to myosin heavy chain (MHC) analysis in order to confirm its type (Type I expressing MHC I, and Type II expressing MHC IId). Type II fibers showed greater steady-state force depression after active shortening at a speed of 0.115 fiber length/s than Type I fibers (14.5±1.5% versus 7.8±1.7%). Moreover, at this absolute shortening speed, Type I fibers showed a significantly greater rate of force decay during shortening and produced less mechanical work than Type II fibers. When active shortening was performed at the same relative speed (17% V0), the difference in force depression between fiber types was abolished. These results suggest that no intrinsic differences were at the origin of the disparate force depressions observed in Type I and Type II fibers when actively shortened at the same absolute speed, but rather their distinct force-velocity relationships.

  16. Early changes in muscle atrophy and muscle fiber type conversion after spinal cord transection and peripheral nerve transection in rats

    PubMed Central

    2013-01-01

    Background Spinal cord transection and peripheral nerve transection cause muscle atrophy and muscle fiber type conversion. It is still unknown how spinal cord transection and peripheral nerve transection each affect the differentiation of muscle fiber type conversion mechanism and muscle atrophy. The aim of our study was to evaluate the difference of muscle weight change, muscle fiber type conversion, and Peroxisome proliferator-activated receptor-γ coactivatior-1α (PGC-1α) expression brought about by spinal cord transection and by peripheral nerve transection. Methods Twenty-four Wistar rats underwent surgery, the control rats underwent a laminectomy; the spinal cord injury group underwent a spinal cord transection; the denervation group underwent a sciatic nerve transection. The rats were harvested of the soleus muscle and the TA muscle at 0 week, 1 week and 2 weeks after surgery. Histological examination was assessed using hematoxylin and eosin (H&E) staining and immunofluorescent staing. Western blot was performed with 3 groups. Results Both sciatic nerve transection and spinal cord transection caused muscle atrophy with the effect being more severe after sciatic nerve transection. Spinal cord transection caused a reduction in the expression of both sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection produced an increase in expression of sMHC protein and PGC-1α protein in the soleus muscle. The results of the expression of PGC-1α were expected in other words muscle atrophy after sciatic nerve transection is less than after spinal cord transection, however muscle atrophy after sciatic nerve transection was more severe than after spinal cord transection. Conclusion In the conclusion, spinal cord transection diminished the expression of sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection enhanced the expression of sMHC protein and PGC-1α protein in the soleus

  17. Effects of fiber type and diet on nuclear magnetic resonance (NMR) relaxation times of skeletal muscle

    SciTech Connect

    Mardini, I.A.; McCarter, R.J.; Fullerton, G.D.

    1986-03-01

    NMR studies of muscle have typically used muscles of mixed fiber composition and have not taken into account the metabolic state of the host. Samples of psoas (type IIB fibers) and soleus (type I fibers) muscles were obtained from 3 groups of rabbits: group C, fed regular chow; group DK fed a potassium deficient diet; and group HC fed a high cholesterol diet. The T/sub 1/ and T/sub 2/ relaxation times of psoas and soleus muscles were not significantly different for group C. Following dietary manipulation, (groups KD and HC), however, the relaxation times of the psoas and soleus muscles were significantly different. There was also a significant difference in water content of psoas muscles in groups KD and HC vs. group C but the observed differences in NMR results could be only partially accounted for by the shift in water content. The authors results suggest that (1) changes in ion or cholesterol concentration are capable of inducing changes in water bonding and structuring in muscle tissues; (2) diet must be added to the growing list of environmental factors that can cause NMR contrast changes; (3) selective use of muscles rich in one fiber type or another for NMR measurements could provide either control or diagnostic information, related to changes in body composition.

  18. Thyroid hormone regulates muscle fiber type conversion via miR-133a1

    PubMed Central

    Zhang, Duo; Wang, Xiaoyun; Li, Yuying; Zhao, Lei; Lu, Minghua; Yao, Xuan; Xia, Hongfeng; Wang, Yu-cheng; Liu, Mo-Fang; Jiang, Jingjing; Li, Xihua

    2014-01-01

    It is known that thyroid hormone (TH) is a major determinant of muscle fiber composition, but the molecular mechanism by which it does so remains unclear. Here, we demonstrated that miR-133a1 is a direct target gene of TH in muscle. Intriguingly, miR-133a, which is enriched in fast-twitch muscle, regulates slow-to-fast muscle fiber type conversion by targeting TEA domain family member 1 (TEAD1), a key regulator of slow muscle gene expression. Inhibition of miR-133a in vivo abrogated TH action on muscle fiber type conversion. Moreover, TEAD1 overexpression antagonized the effect of miR-133a as well as TH on muscle fiber type switch. Additionally, we demonstrate that TH negatively regulates the transcription of myosin heavy chain I indirectly via miR-133a/TEAD1. Collectively, we propose that TH inhibits the slow muscle phenotype through a novel epigenetic mechanism involving repression of TEAD1 expression via targeting by miR-133a1. This identification of a TH-regulated microRNA therefore sheds new light on how TH achieves its diverse biological activities. PMID:25512392

  19. Electrically and Hybrid-Induced Muscle Activations: Effects of Muscle Size and Fiber Type

    PubMed Central

    Stratton, Kelly; Faghri, Pouran D.

    2016-01-01

    The effect of three electrical stimulation (ES) frequencies (10, 35, and 50 Hz) on two muscle groups with different proportions of fast and slow twitch fibers (abductor pollicis brevis (APB) and vastus lateralis (VL)) was explored. We evaluated the acute muscles’ responses individually and during hybrid activations (ES superimposed by voluntary activations). Surface electromyography (sEMG) and force measurements were evaluated as outcomes. Ten healthy adults (mean age: 24.4 ± 2.5 years) participated after signing an informed consent form approved by the university Institutional Review Board. Protocols were developed to: 1) compare EMG activities during each frequency for each muscle when generating 25% Maximum Voluntary Contraction (MVC) force, and 2) compare EMG activities during each frequency when additional voluntary activation was superimposed over ES-induced 25% MVC to reach 50% and 75% MVC. Empirical mode decomposition (EMD) was utilized to separate ES artifacts from voluntary muscle activation. For both muscles, higher stimulation frequency (35 and 50Hz) induced higher electrical output detected at 25% of MVC, suggesting more recruitment with higher frequencies. Hybrid activation generated proportionally less electrical activity than ES alone. ES and voluntary activations appear to generate two different modes of muscle recruitment. ES may provoke muscle strength by activating more fatiguing fast acting fibers, but voluntary activation elicits more muscle coordination. Therefore, during the hybrid activation, less electrical activity may be detected due to recruitment of more fatigue-resistant deeper muscle fibers, not reachable by surface EMG. PMID:27990244

  20. Fiber type composition of the muscle responsible for throat fan extension in green anole lizards.

    PubMed

    Rosen, G J; O'Bryant, E L; Swender, D; Wade, J

    2004-01-01

    Throat fan (dewlap) extension is sexually dimorphic in green anole lizards (Anolis carolinensis). Males have larger dewlaps which they display more frequently than females. Correlated with the behavior, sexual dimorphisms occur in the skeletal, muscular and neural structures responsible for dewlap extension in green anoles. We used histochemical techniques to stain for myosin ATPase and succinate dehydrogenase (SDH) to determine whether sex differences also exist in fiber type composition of the ceratohyoideus, the muscle that extends the dewlap. Based on the staining pattern for the two enzymes, four fiber types were identified: fast-oxidative-glycolytic (FOG), fast-glycolytic (FG), slow-oxidative (SO), and tonic. In the ceratohyoideus of both sexes, the predominate fiber types were FOG (approximately 43%) and FG (approximately 34%). Also in both males and females, the FOG and FG fibers had approximately twice the cross-sectional area of the SO and tonic fibers. No sex differences occurred in the percentages of FOG and FG fibers. However, males had a greater percentage of tonic fibers than females, whereas females had a greater percentage of SO fibers than males. The high proportion of FOG fibers in the anole ceratohyoideus makes it similar to other relatively fatigue-resistant muscles used in movements of moderate speed and duration. Although the precise role of tonic fibers in dewlap extension is not known, the greater percentage of these fibers in the male ceratohyoideus might be required to stabilize or maintain extension of the large dewlap apparatus in males.

  1. Distinct muscle apoptotic pathways are activated in muscles with different fiber types a rat model of critical illness myopathy

    PubMed Central

    Barnes, Benjamin T.; Confides, Amy L.; Rich, Mark M.; Dupont-Versteegden, Esther E.

    2015-01-01

    Critical illness myopathy (CIM) is associated with severe muscle atrophy and fatigue in affected patients. Apoptotic signaling is involved in atrophy and is elevated in muscles from patients with CIM. In this study we investigated underlying mechanisms of apoptosis-related pathways in muscles with different fiber type composition in a rat model of CIM using denervation and glucocorticoid administration (denervation and steroid-induced myopathy, DSIM). Soleus and tibialis anterior (TA) muscles showed severe muscle atrophy (40–60% of control muscle weight) and significant apoptosis in interstitial as well as myofiber nuclei that was similar between the two muscles with DSIM. Caspase-3 and −8 activities, but not caspase-9 and −12, were elevated in TA and not in soleus muscle, while the caspase-independent proteins endonuclease G (EndoG) and apoptosis inducing factor (AIF) were not changed in abundance nor differentially localized in either muscle. Anti-apoptotic proteins HSP70, −27, and apoptosis repressor with a caspase recruitment domain (ARC) were elevated in soleus compared to TA muscle and ARC was significantly decreased with induction of DSIM in soleus. Results indicate that apoptosis is a significant process associated with DSIM in both soleus and TA muscles, and that apoptosis-associated processes are differentially regulated in muscles of different function and fiber type undergoing atrophy due to DSIM. We conclude that interventions combating apoptosis with CIM may need to be directed towards inhibiting caspase-dependent as well as -independent mechanisms to be able to affect muscles of all fiber types. PMID:25740800

  2. Distinct muscle apoptotic pathways are activated in muscles with different fiber types in a rat model of critical illness myopathy.

    PubMed

    Barnes, Benjamin T; Confides, Amy L; Rich, Mark M; Dupont-Versteegden, Esther E

    2015-06-01

    Critical illness myopathy (CIM) is associated with severe muscle atrophy and fatigue in affected patients. Apoptotic signaling is involved in atrophy and is elevated in muscles from patients with CIM. In this study we investigated underlying mechanisms of apoptosis-related pathways in muscles with different fiber type composition in a rat model of CIM using denervation and glucocorticoid administration (denervation and steroid-induced myopathy, DSIM). Soleus and tibialis anterior (TA) muscles showed severe muscle atrophy (40-60% of control muscle weight) and significant apoptosis in interstitial as well as myofiber nuclei that was similar between the two muscles with DSIM. Caspase-3 and -8 activities, but not caspase-9 and -12, were elevated in TA and not in soleus muscle, while the caspase-independent proteins endonuclease G (EndoG) and apoptosis inducing factor (AIF) were not changed in abundance nor differentially localized in either muscle. Anti-apoptotic proteins HSP70, -27, and apoptosis repressor with a caspase recruitment domain (ARC) were elevated in soleus compared to TA muscle and ARC was significantly decreased with induction of DSIM in soleus. Results indicate that apoptosis is a significant process associated with DSIM in both soleus and TA muscles, and that apoptosis-associated processes are differentially regulated in muscles of different function and fiber type undergoing atrophy due to DSIM. We conclude that interventions combating apoptosis with CIM may need to be directed towards inhibiting caspase-dependent as well as -independent mechanisms to be able to affect muscles of all fiber types.

  3. Nuclear receptor/microRNA circuitry links muscle fiber type to energy metabolism.

    PubMed

    Gan, Zhenji; Rumsey, John; Hazen, Bethany C; Lai, Ling; Leone, Teresa C; Vega, Rick B; Xie, Hui; Conley, Kevin E; Auwerx, Johan; Smith, Steven R; Olson, Eric N; Kralli, Anastasia; Kelly, Daniel P

    2013-06-01

    The mechanisms involved in the coordinate regulation of the metabolic and structural programs controlling muscle fitness and endurance are unknown. Recently, the nuclear receptor PPARβ/δ was shown to activate muscle endurance programs in transgenic mice. In contrast, muscle-specific transgenic overexpression of the related nuclear receptor, PPARα, results in reduced capacity for endurance exercise. We took advantage of the divergent actions of PPARβ/δ and PPARα to explore the downstream regulatory circuitry that orchestrates the programs linking muscle fiber type with energy metabolism. Our results indicate that, in addition to the well-established role in transcriptional control of muscle metabolic genes, PPARβ/δ and PPARα participate in programs that exert opposing actions upon the type I fiber program through a distinct muscle microRNA (miRNA) network, dependent on the actions of another nuclear receptor, estrogen-related receptor γ (ERRγ). Gain-of-function and loss-of-function strategies in mice, together with assessment of muscle biopsies from humans, demonstrated that type I muscle fiber proportion is increased via the stimulatory actions of ERRγ on the expression of miR-499 and miR-208b. This nuclear receptor/miRNA regulatory circuit shows promise for the identification of therapeutic targets aimed at maintaining muscle fitness in a variety of chronic disease states, such as obesity, skeletal myopathies, and heart failure.

  4. The Regulation of Skeletal Muscle Active Hyperemia: The Differential Role of Adenosine in Muscles of Varied Fiber Types

    DTIC Science & Technology

    1986-04-21

    0.2 Hz and three mnscles ~;timulated to contract at 0.4 Hz during BADA infuston. These m~tabolites were also mea~•1red in two muscles contractin ~ at...APR 1986 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE The Regulation of Skeletal Muscle Active Hyperemia: The Differential...Role of Adenosine in Muscles of Varied Fiber Types 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER

  5. Effect of 23-day muscle disuse on sarcoplasmic reticulum Ca2+ properties and contractility in human type I and type II skeletal muscle fibers.

    PubMed

    Lamboley, C R; Wyckelsma, V L; Perry, B D; McKenna, M J; Lamb, G D

    2016-08-01

    Inactivity negatively impacts on skeletal muscle function mainly through muscle atrophy. However, recent evidence suggests that the quality of individual muscle fibers is also altered. This study examined the effects of 23 days of unilateral lower limb suspension (ULLS) on specific force and sarcoplasmic reticulum (SR) Ca(2+) content in individual skinned muscle fibers. Muscle biopsies of the vastus lateralis were taken from six young healthy adults prior to and following ULLS. After disuse, the endogenous SR Ca(2+) content was ∼8% lower in type I fibers and maximal SR Ca(2+) capacity was lower in both type I and type II fibers (-11 and -5%, respectively). The specific force, measured in single skinned fibers from three subjects, decreased significantly after ULLS in type II fibers (-23%) but not in type I fibers (-9%). Western blot analyses showed no significant change in the amounts of myosin heavy chain (MHC) I and MHC IIa following the disuse, whereas the amounts of sarco(endo)plasmic reticulum Ca(2+)-ATPase 1 (SERCA1) and calsequestrin increased by ∼120 and ∼20%, respectively, and the amount of troponin I decreased by ∼21%. These findings suggest that the decline in force and power occurring with muscle disuse is likely to be exacerbated in part by reductions in maximum specific force in type II fibers, and in the amount of releasable SR Ca(2+) in both fiber types, the latter not being attributable to a reduced calsequestrin level. Furthermore, the ∼3-wk disuse in human elicits change in SR properties, in particular a more than twofold upregulation in SERCA1 density, before any fiber-type shift.

  6. Effects of disuse by limb immobilization on different muscle fiber types

    NASA Technical Reports Server (NTRS)

    Booth, F. W.; Seider, M. J.; Hugman, G. R.

    1980-01-01

    The effects of disuse by limb immobilization on different muscle fiber types are reviewed. It is demonstrated that many changes occurring in atrophying skeletal muscles of young rats can be explained by the duration of the half-lives of muscle proteins. Differences are found to exist in responses of fast- and slow-twitch muscles due to disuse atrophy, and the appearance of plasticity in skeletal muscle begins to occur very soon after changes in the level of contractile activity. Rates of protein degradation increase in slow-twitch muscles at rapidly growing rates after approximately one day of limb immobilization; however, no change in the rates of protein degradation is noted in fast-twitch muscles of young rats.

  7. De novo synthesis of adenine nucleotides in different skeletal muscle fiber types

    SciTech Connect

    Tullson, P.C.; John-Alder, H.B.; Hood, D.A.; Terjung, R.L.

    1988-09-01

    Management of adenine nucleotide catabolism differs among skeletal muscle fiber types. This study evaluated whether there are corresponding differences in the rates of de novo synthesis of adenine nucleotide among fiber type sections of skeletal muscle using an isolated perfused rat hindquarter preparation. Label incorporation into adenine nucleotides from the (1-14C)glycine precursor was determined and used to calculate synthesis rates based on the intracellular glycine specific radioactivity. Results show that intracellular glycine is closely related to the direct precursor pool. Rates of de novo synthesis were highest in fast-twitch red muscle (57.0 +/- 4.0, 58.2 +/- 4.4 nmol.h-1.g-1; deep red gastrocnemius and vastus lateralis), relatively high in slow-twitch red muscle (47.0 +/- 3.1; soleus), and low in fast-twitch white muscle (26.1 +/- 2.0 and 21.6 +/- 2.3; superficial white gastrocnemius and vastus lateralis). Rates for four mixed muscles were intermediate, ranging between 32.3 and 37.3. Specific de novo synthesis rates exhibited a strong correlation (r = 0.986) with muscle section citrate synthase activity. Turnover rates (de novo synthesis rate/adenine nucleotide pool size) were highest in high oxidative muscle (0.82-1.06%/h), lowest in low oxidative muscle (0.30-0.35%/h), and intermediate in mixed muscle (0.44-0.55%/h). Our results demonstrate that differences in adenine nucleotide management among fiber types extends to the process of de novo adenine nucleotide synthesis.

  8. Association of blood glucose, blood lactate, serum cortisol levels, muscle metabolites, muscle fiber type composition, and pork quality traits.

    PubMed

    Choe, J H; Kim, B C

    2014-06-01

    The objective of this study was to investigate the relationship of blood glucose levels with blood lactate, serum cortisol levels, postmortem muscle glycogen and lactate content, muscle fiber type composition, and pork quality traits. Compared to pigs with lower blood glucose levels, pigs with higher blood glucose levels showed higher blood lactate and serum cortisol levels at exsanguination, and they had lower residual glycogen and higher lactate content in the muscle at 45min postmortem. In addition, pigs with higher blood glucose levels had higher type IIB and lower type I area composition and finally exhibited lower muscle pH, paler color, and excessive loss of fluid on surface. These results imply that measuring blood glucose levels at exsanguination can be useful to indicate early glycolytic rates during postmortem and thus may be of value in the identification of pork with undesirable quality traits.

  9. Thin filament diversity and physiological properties of fast and slow fiber types in astronaut leg muscles

    NASA Technical Reports Server (NTRS)

    Riley, Danny A.; Bain, James L W.; Thompson, Joyce L.; Fitts, Robert H.; Widrick, Jeffrey J.; Trappe, Scott W.; Trappe, Todd A.; Costill, David L.

    2002-01-01

    Slow type I fibers in soleus and fast white (IIa/IIx, IIx), fast red (IIa), and slow red (I) fibers in gastrocnemius were examined electron microscopically and physiologically from pre- and postflight biopsies of four astronauts from the 17-day, Life and Microgravity Sciences Spacelab Shuttle Transport System-78 mission. At 2.5-microm sarcomere length, thick filament density is approximately 1,012 filaments/microm(2) in all fiber types and unchanged by spaceflight. In preflight aldehyde-fixed biopsies, gastrocnemius fibers possess higher percentages (approximately 23%) of short thin filaments than soleus (9%). In type I fibers, spaceflight increases short, thin filament content from 9 to 24% in soleus and from 26 to 31% in gastrocnemius. Thick and thin filament spacing is wider at short sarcomere lengths. The Z-band lattice is also expanded, except for soleus type I fibers with presumably stiffer Z bands. Thin filament packing density correlates directly with specific tension for gastrocnemius fibers but not soleus. Thin filament density is inversely related to shortening velocity in all fibers. Thin filament structural variation contributes to the functional diversity of normal and spaceflight-unloaded muscles.

  10. Fiber type specific expression of TNF-alpha, IL-6 and IL-18 in human skeletal muscles.

    PubMed

    Plomgaard, Peter; Penkowa, Milena; Pedersen, Bente K

    2005-01-01

    Skeletal muscle is now recognized as an endocrine organ with the capacity to produce signal peptides in response to muscle contractions. Here we demonstrate that resting healthy human muscles express cytokines in a fiber type specific manner. Human muscle biopsies from seven healthy young males were obtained from m. triceps, m. quadriceps vastus lateralis and m. soleus. Type I fibers contributed (mean +/- SE) 24.0 +/- 2.5% in triceps of total fibers, 51.3 +/- 2.4% in vastus and 84.9 +/- 22% in soleus. As expected, differences in the fiber type composition were accompanied by marked differences between the three muscles with regard to MHC I and MHC IIa mRNA expression. Immunohistochemistry demonstrated that tumor necrosis factor (TNF)-alpha and interleukin (IL)-18 were solely expressed by type II fibers, whereas the expression of IL-6 was more prominent in type I compared to type II fibers. The fiber type specificity was found in triceps, vastus and soleus indicating that the level of daily muscle activity did not influence basal cytokine expression. The specificity of cytokine expression in different muscle fiber types in healthy young males suggests that cytokines may play specific regulatory roles in normal physiology.

  11. Quantitative PCR Analysis of Laryngeal Muscle Fiber Types

    ERIC Educational Resources Information Center

    Van Daele, Douglas J.

    2010-01-01

    Voice and swallowing dysfunction as a result of recurrent laryngeal nerve paralysis can be improved with vocal fold injections or laryngeal framework surgery. However, denervation atrophy can cause late-term clinical failure. A major determinant of skeletal muscle physiology is myosin heavy chain (MyHC) expression, and previous protein analyses…

  12. Skeletal fiber types and spindle distribution in limb and jaw muscles of the adult and neonatal opossum, Monodelphis domestica.

    PubMed

    Sciote, J J; Rowlerson, A

    1998-08-01

    The South American opossum, Monodelphis domestica, is very immature at birth, and we wished to assess its potential for studies of jaw muscle development. Given the lack of prior information about any Monodelphis fiber types or spindles, our study aimed to identify for the first time fiber types in both adult and neonatal muscles and the location of spindles in the jaw muscles. Fiber types were identified in frozen sections of adult and 6-day-old jaw and limb muscles by using myosin ATPase and metabolic enzyme histochemistry and by immunostaining for myosin isoforms. The distribution of fiber types and muscle spindles throughout the jaw-closer muscles was identified by immunostaining of sections of methacarnoy-fixed, wax-embedded heads. Most muscles contained one slow (type I) and two fast fiber types (equivalent to types IIA and IIX), which were similar to those in eutherian muscle, and an additional (non-IIB) fast type. In jaw-closer muscles, the main extrafusal fiber type was IIM (characteristic of these muscles in some eutherians), and almost all spindles were concentrated in four restricted areas: one in masseter and three in temporalis. Six-day neonatal muscles were very immature, but future spindle-rich areas were revealed by immunostaining and corresponded in position to the adult areas. Extrafusal and spindle fiber types in Monodelphis share many similarities with eutherian mammalian muscle. This finding, along with the immaturity of myosin isoform expression observed 6 days postnatally, indicates that Monodelphis could provide a valuable model for studying early developmental events in the jaw-closer muscles and their spindles.

  13. Correlation between histochemically assessed fiber type distribution and isomyosin and myosin heavy chain content in porcine skeletal muscles.

    PubMed

    Bee, G; Solomon, M B; Czerwinski, S M; Long, C; Pursel, V G

    1999-08-01

    Highly sensitive enzyme assays developed to differentiate skeletal muscle fibers allow the recognition of three main fiber types: slow-twitch oxidative (SO), fast-twitch oxidative glycolytic (FOG), and fast-twitch glycolytic (FG). Myosin, the predominant contractile protein in mammalian skeletal muscle, can be separated based on the electrophoretic mobility under nondissociating conditions into SM2, SM1, IM, FM3, and FM2 isoforms, or under dissociating conditions into myosin heavy chain (MHC) I, IIb, IIx/d, and IIa. The purpose of the present study was to determine whether the histochemical method of differentiation of fiber types is consistent with the electrophoretically identified isomyosin and MHC isoforms. These comparisons were made using serratus ventralis (SV), gluteus medius (GM), and longissimus muscles (LM) from 13 pigs. Two calculation methods for the histochemical assessed fiber type distribution were adopted. The first method incorporated the number of fibers counted for each fiber type and calculated a percentage of the total fiber number (fiber number percentage: FNP). The second method expressed the cross-sectional area of each fiber type as a percentage of the total fiber area measured per muscle (fiber area percentage: FAP). Independent of the calculation methods, correlation analyses revealed in all muscles a strong relation between SO fibers, the slow isomyosin (SM1 and SM2), and MHCI, as well as between the FG fibers, the fast isomyosin (FM3 and FM2), and MHCIIx/b content (P<.05). There were no correlations between FOG fiber population assessed by histochemical analysis and intermediate isoform (IM) or MHCIIa content. The present results did not provide conclusive evidence as to which of the calculation methods (FNP or FAP) was more closely related to myosin composition of skeletal muscles. Despite some incompatibility between the methods, the present study shows that histochemical as well as electrophoretic analyses yielded important

  14. Influence of Fiber-Type Composition on Recovery from Tourniquet-Induced Skeletal Muscle Ischemia-Reperfusion Injury

    DTIC Science & Technology

    2008-03-11

    free flaps . J. Surg. Res. 55: 193–200. doi:10.1006/jsre.1993.1129. PMID:8412099. Locke, M., and Tanguay, R.M. 1996. Increased HSF activation in muscles...Influence of fiber-type composition on recovery from tourniquet-induced skeletal muscle ischemia –reperfusion injury Thomas J. Walters, John F. Kragh...of predominantly different fiber types occurs following extended periods of ischemia . We hypothe- sized that the soleus (Sol) muscle, a predominantly

  15. Comparative analysis of fiber-type composition in the iliofibularis muscle of phrynosomatid lizards (Squamata).

    PubMed

    Bonine, K E; Gleeson, T T; Garland, T

    2001-12-01

    The lizard family Phrynosomatidae comprises three subclades: the closely related sand and horned lizards, and their relatives the Sceloporus group. This family exhibits great variation in ecology, behavior, and general body plan. Previous studies also show that this family exhibits great diversity in locomotor performance abilities; as measured on a high-speed treadmill, sand lizards are exceptionally fast sprinters, members of the Sceloporus group are intermediate, and horned lizards are slowest. These differences are paralleled by differences in relative hindlimb span. To determine if muscle fiber-type composition also varies among the three subclades, we examined the iliofibularis (IF), a hindlimb muscle used in lizard locomotion, in 11 species of phrynosomatid lizards. Using histochemical assays for myosin ATPase, an indicator of fast-twitch capacity, and succinic dehydrogenase, denoting oxidative capacity, we classified fiber types into three categories based on existing nomenclature: fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG), and slow-twitch oxidative (SO). Sand lizards have a high proportion of FG fibers (64-70%) and a low proportion of FOG fibers (25-33%), horned lizards are the converse (FG fibers 25-31%, FOG fibers 56-66%), and members of the Sceloporus group are intermediate for both FG (41-48%) and FOG (42-45%) content. Hence, across all 11 species %FOG and %FG are strongly negatively correlated. Analysis with phylogenetically independent contrasts indicate that this negative relationship is entirely attributable to the divergence between sand and horned lizards. The %SO also varies among the three subclades. Results from conventional nested ANCOVA (with log body mass as a covariate) indicate that the log mean cross-sectional area of individual muscle fibers differs among species and is positively correlated with body mass across species, but does not differ significantly among subclades. The log cross-sectional area of the IF

  16. Severe insulin-resistant diabetes mellitus in patients with congenital muscle fiber type disproportion myopathy.

    PubMed

    Vestergaard, H; Klein, H H; Hansen, T; Müller, J; Skovby, F; Bjørbaek, C; Røder, M E; Pedersen, O

    1995-04-01

    Congenital muscle fiber type disproportion myopathy (CFTDM) is a chronic, nonprogressive muscle disorder characterized by universal muscle hypotrophy and growth retardation. Histomorphometric examination of muscle shows a preponderance of smaller than normal type 1 fibers and overall fiber size heterogeneity. Concomitant endocrine dysfunctions have not been described. We report the findings of altered insulin secretion and insulin action in two brothers affected with CFTDM and glucose intolerance as well as in their nonconsanguineous glucose-tolerant parents. Results are compared with those of six normoglycemic control subjects. All study participants underwent an oral glucose tolerance test to estimate insulin secretion. The oldest boy and his parents volunteered for studies of whole-body insulin sensitivity consisting of a 4-h euglycemic hyperinsulinemic clamp in combination with indirect calorimetry. Insulin receptor function and glycogen synthase (GS) activity and expression were examined in biopsies of vastus lateralis muscle. Despite a 45-90-fold increase in both fasting and postprandial serum insulin levels, both CFTDM patients had diabetes mellitus. Clamp studies revealed that the oldest boy had severe insulin resistance of both liver and peripheral tissues. The impaired insulin-stimulated glucose disposal to peripheral tissues was primarily due to reduced nonoxidative glucose metabolism. These changes were paralleled by reduced basal values of muscle GS total activity, allosterical activation of GS by glucose-6-phosphate, GS protein, and GS mRNA. The father expressed a lesser degree of insulin resistance, and studies of muscle insulin receptor function showed a severe impairment of receptor kinase activity. In conclusion, CFTDM is a novel form of severe hyperinsulinemia and insulin resistance. Whether insulin resistance is causally related to the muscle disorder awaits to be clarified.

  17. Some properties of different skeletal muscle fiber types: comparison of reference bases.

    PubMed

    Kelso, T B; Hodgson, D R; Visscher, A R; Gollnick, P D

    1987-04-01

    Several biochemical components of the white portion of the gastrocnemius (WGM), plantaris (PM), and soleus (SM) muscles of the rat and middle gluteal (MGM) muscle of the horse were compared based on wet and dry weight, protein, and total creatine concentrations ([TCr]). The water content was similar for the rat hindlimb muscles, however, the concentrations of protein, ATP, phosphocreatine (PCr), creatine, and glycogen ranked as SM less than PM less than WGM for all reference bases except total creatine. In contrast, concentrations of ATP, creatine, and PCr were similar in all muscles studied when expressed as ratios of [TCr]. Horse MGM had the lowest percent of water and protein per gram wet or dry weight but highest glycogen concentration of the muscles studied, irrespective of the reference base used to express concentrations. Coefficients of variation were lowest when muscle constituents were related to [TCr]. It is concluded that expressing muscle constituents relative to total creatine results in the smallest variation and is a good method for making comparisons between muscles of similar fiber composition. However, essential information concerning different types of muscle may be lost when this reference base is used.

  18. Carnitine supplementation to obese Zucker rats prevents obesity-induced type II to type I muscle fiber transition and favors an oxidative phenotype of skeletal muscle

    PubMed Central

    2013-01-01

    Background In the present study, we tested the hypothesis that carnitine supplementation counteracts obesity-induced muscle fiber transition from type I to type II. Methods 24 obese Zucker rats were randomly divided into two groups of 12 rats each (obese control, obese carnitine) and 12 lean Zucker rats were selected for lean control group. A control diet was given to both control groups and a carnitine supplemented diet (3 g/kg diet) was given to obese carnitine group for 4 wk. Components of the muscle fiber transformation in skeletal muscle were examined. Results The plasma level of carnitine were lower in the obese control group compared to the lean control group and higher in the obese carnitine group than in the other groups (P < 0.05). Plasma concentrations of triglycerides and non-esterified fatty acids were increased in obese animals compared to lean animals and the obese carnitine group had lower level compared to the obese control group (P < 0.05). The obese carnitine group had an increased number of type I muscle fibers and higher mRNA levels of type I fiber-specific myosin heavy chain, regulators of muscle fiber transition and of genes involved in carnitine uptake, fatty acid transport, β-oxidation, angiogenesis, tricarboxylic acid cycle and thermo genesis in M. rectus femoris compared to the other groups (P < 0.05). Conclusion The results demonstrate that carnitine supplementation to obese Zucker a rat counteracts the obesity-induced muscle fiber transition and restores the muscle oxidative metabolic phenotype. Carnitine supplementation is supposed to be beneficial for the treatment of elevated levels of plasma lipids during obesity or diabetes. PMID:23842456

  19. Fiber type and metabolic characteristics of lion (Panthera leo), caracal (Caracal caracal) and human skeletal muscle.

    PubMed

    Kohn, Tertius Abraham; Burroughs, Richard; Hartman, Marthinus Jacobus; Noakes, Timothy David

    2011-06-01

    Lion (Panthera leo) and caracal (Caracal caracal) skeletal muscle samples from Vastus lateralis, Longissimus dorsi and Gluteus medius were analyzed for fiber type and citrate synthase (CS; EC 2.3.3.1), 3-hydroxyacyl Co A dehydrogenase (3HAD; EC 1.1.1.35), phosphofructokinase-1 (PFK; EC 2.7.1.11), creatine kinase (CK; EC 2.7.3.2), phosphorylase (PHOS; EC 2.4.1.1) and lactate dehydrogenase (LDH; EC 1.1.1.27) activities and compared to human runners, the latter also serving as validation of methodology. Both felids had predominantly type IIx fibers (range 50-80%), whereas human muscle had more types I and IIa. Oxidative capacity of both felids (CS: 5-9 μmol/min/g ww and 3HAD: 1.4-2.6 μmol/min/g ww) was lower than humans, whereas the glycolytic capacity was elevated. LDH activity of caracal (346 ± 81) was higher than lion (227 ± 62 μmol/min/g ww), with human being the lowest (55 ± 17). CK and PHOS activities were also higher in caracal and lion compared to human, but PFK was lower in both felid species. The current data and past research are illustrated graphically showing a strong relationship between type II fibers and sprinting ability in various species. These data on caracal and lion muscles confirm their sprinting behavior.

  20. Alteration of inflammatory cytokines, energy metabolic regulators, and muscle fiber type in the skeletal muscle of postweaning piglets.

    PubMed

    Li, F; Li, Y; Tan, B; Wang, J; Duan, Y; Guo, Q; Liu, Y; Kong, X; Li, T; Tang, Y; Yin, Y

    2016-03-01

    This study was conducted to determine the alterations of inflammatory cytokines, energy metabolic regulators, and muscle fiber type in the LM of the piglets postweaning. Crossbred piglets (Landrace × Large White) weaned at 14 d age were randomly selected from 8 litters and slaughtered at 0 (W0), 1 (W1), 3 (W3), 5 (W5), or 7 (W7) days postweaning. The glycogen content, free glucose concentration, and enzyme activities, including ATPase (Na/K, Ca/Mg), creatine kinase, and lactic dehydrogenase (LDH), were detected in the skeletal muscle tissue. Concentrations of proinflammatory cytokines, including IL-1β, IL-6, and tumor necrosis factor-α (TNF-α), and anti-inflammatory cytokines, including IL-10 and transforming growth factor-β1 (TGF-β1), were measured in serum. The mRNA abundance of the above cytokines, energy metabolic regulators, and muscle fiber type related genes were determined via real-time quantitative PCR analysis. The adenosine monophosphate-activated protein kinase α (AMPKα) signaling was measured by Western blot analysis. Our results showed ATPase activities were lower on W7 d but LDH activity was higher on W3 d after weaning ( < 0.05). Serum TNF-α concentration was markedly increased on W1 d, then returned to the value of preweaning ( < 0.05), and almost all the values of inflammatory cytokines were reduced to a low point on W5 d after weaning. Additionally, the IL-6 mRNA abundance was upregulated during W3 to W7 d, but cytokine TNF-α was upregulated just on W7 d ( < 0.05). The mRNA abundance of AMPKα and uncoupling protein (UCP) 3 were both higher on W1 and W3 d, and UCP2 was higher on W7 d postweaning ( < 0.05). Myosin heavy chain (MyHC) I and MyHC IIx-type fibers were enhanced on W1 d, then returned to the value of preweaning, and the MyHC IIb-type fiber was significantly increased on W5 and W7 d ( < 0.05). Meanwhile, the value of P-AMPKα/T-AMPKα increased on W3 d postweaning ( < 0.05) compared with that on W0 d. These results indicate

  1. Nitrate Intake Promotes Shift in Muscle Fiber Type Composition during Sprint Interval Training in Hypoxia

    PubMed Central

    De Smet, Stefan; Van Thienen, Ruud; Deldicque, Louise; James, Ruth; Sale, Craig; Bishop, David J.; Hespel, Peter

    2016-01-01

    Purpose: We investigated the effect of sprint interval training (SIT) in normoxia, vs. SIT in hypoxia alone or in conjunction with oral nitrate intake, on buffering capacity of homogenized muscle (βhm) and fiber type distribution, as well as on sprint and endurance performance. Methods: Twenty-seven moderately-trained participants were allocated to one of three experimental groups: SIT in normoxia (20.9% FiO2) + placebo (N), SIT in hypoxia (15% FiO2) + placebo (H), or SIT in hypoxia + nitrate supplementation (HN). All participated in 5 weeks of SIT on a cycle ergometer (30-s sprints interspersed by 4.5 min recovery-intervals, 3 weekly sessions, 4–6 sprints per session). Nitrate (6.45 mmol NaNO3) or placebo capsules were administered 3 h before each session. Before and after SIT participants performed an incremental VO2max-test, a 30-min simulated cycling time-trial, as well as a 30-s cycling sprint test. Muscle biopsies were taken from m. vastus lateralis. Results: SIT decreased the proportion of type IIx muscle fibers in all groups (P < 0.05). The relative number of type IIa fibers increased (P < 0.05) in HN (P < 0.05 vs. H), but not in the other groups. SIT had no significant effect on βhm. Compared with H, SIT tended to enhance 30-s sprint performance more in HN than in H (P = 0.085). VO2max and 30-min time-trial performance increased in all groups to a similar extent. Conclusion: SIT in hypoxia combined with nitrate supplementation increases the proportion of type IIa fibers in muscle, which may be associated with enhanced performance in short maximal exercise. Compared with normoxic training, hypoxic SIT does not alter βhm or endurance and sprinting exercise performance. PMID:27378942

  2. Muscle fiber-type variation in lizards (Squamata) and phylogenetic reconstruction of hypothesized ancestral states.

    PubMed

    Bonine, Kevin E; Gleeson, Todd T; Garland, Theodore

    2005-12-01

    Previously, we found that phrynosomatid lizards, a diverse group common in the southwestern USA, vary markedly in fiber-type composition of the iliofibularis (a hindlimb muscle important in locomotion). Phrynosomatidae comprises three subclades: the closely related sand and horned lizards, and their relatives the Sceloporus group. The variation in muscle fiber-type composition for 11 phrynosomatid species is attributable mainly to differences between the sand- and horned-lizard subclades. Here, we expand the phrynosomatid database with three additional species and compare these results with data collected for 10 outgroup (distantly related) species. Our goal was to determine if the patterns found in Phrynosomatidae hold across a broader phylogenetic range of the extant lizards and to elucidate the evolution of muscle fiber-type composition and related traits. To allow for meaningful comparisons, data were collected from species that are primarily terrestrial and relatively small in size (3.5-65 g body mass). Results indicate that the fiber-type variation observed within the Phrynosomatidae almost spans the range of variation observed in our sample of 24 species from eight families. However, one species of Acanthodactylus (Lacertidae) had a consistent region of large tonic fibers (that did not stain darkly for either succinic dehydrogenase or myosin ATPase activity), a fiber-type only occasionally seen in the other 23 species examined. Many species have a large proportion of either fast-twitch glycolytic (FG; e.g. sand lizards and Aspidoscelis) or fast-twitch oxidative-glycolytic (FOG) fibers (e.g. horned lizards), with the slow-oxidative proportion occupying only 1-17% of the iliofibularis. Importantly, the negative relationship between FG and FOG composition observed in Phrynosomatidae appears to be a characteristic of lizards in general, and could lead to functional trade-offs in aspects of locomotor performance, as has previously been reported for Lacertidae

  3. Abnormal Skeletal Muscle Regeneration plus Mild Alterations in Mature Fiber Type Specification in Fktn-Deficient Dystroglycanopathy Muscular Dystrophy Mice

    PubMed Central

    Foltz, Steven J.; Modi, Jill N.; Melick, Garrett A.; Abousaud, Marin I.; Luan, Junna; Fortunato, Marisa J.; Beedle, Aaron M.

    2016-01-01

    Glycosylated α-dystroglycan provides an essential link between extracellular matrix proteins, like laminin, and the cellular cytoskeleton via the dystrophin-glycoprotein complex. In secondary dystroglycanopathy muscular dystrophy, glycosylation abnormalities disrupt a complex O-mannose glycan necessary for muscle structural integrity and signaling. Fktn-deficient dystroglycanopathy mice develop moderate to severe muscular dystrophy with skeletal muscle developmental and/or regeneration defects. To gain insight into the role of glycosylated α-dystroglycan in these processes, we performed muscle fiber typing in young (2, 4 and 8 week old) and regenerated muscle. In mice with Fktn disruption during skeletal muscle specification (Myf5/Fktn KO), newly regenerated fibers (embryonic myosin heavy chain positive) peaked at 4 weeks old, while total regenerated fibers (centrally nucleated) were highest at 8 weeks old in tibialis anterior (TA) and iliopsoas, indicating peak degeneration/regeneration activity around 4 weeks of age. In contrast, mature fiber type specification at 2, 4 and 8 weeks old was relatively unchanged. Fourteen days after necrotic toxin-induced injury, there was a divergence in muscle fiber types between Myf5/Fktn KO (skeletal-muscle specific) and whole animal knockout induced with tamoxifen post-development (Tam/Fktn KO) despite equivalent time after gene deletion. Notably, Tam/Fktn KO retained higher levels of embryonic myosin heavy chain expression after injury, suggesting a delay or abnormality in differentiation programs. In mature fiber type specification post-injury, there were significant interactions between genotype and toxin parameters for type 1, 2a, and 2x fibers, and a difference between Myf5/Fktn and Tam/Fktn study groups in type 2b fibers. These data suggest that functionally glycosylated α-dystroglycan has a unique role in muscle regeneration and may influence fiber type specification post-injury. PMID:26751696

  4. Differential Expression of NADPH Oxidases Depends on Skeletal Muscle Fiber Type in Rats

    PubMed Central

    Loureiro, Adriano César Carneiro; do Rêgo-Monteiro, Igor Coutinho; Louzada, Ruy A.; Ortenzi, Victor Hugo; de Aguiar, Angélica Ponte; de Abreu, Ewerton Sousa; Cavalcanti-de-Albuquerque, João Paulo Albuquerque; Hecht, Fabio; de Oliveira, Ariclécio Cunha; Ceccatto, Vânia Marilande; Fortunato, Rodrigo S.

    2016-01-01

    NADPH oxidases (NOX) are important sources of reactive oxygen species (ROS) in skeletal muscle, being involved in excitation-contraction coupling. Thus, we aimed to investigate if NOX activity and expression in skeletal muscle are fiber type specific and the possible contribution of this difference to cellular oxidative stress. Oxygen consumption rate, NOX activity and mRNA levels, and the activity of catalase (CAT), glutathione peroxidase (GPX), and superoxide dismutase (SOD), as well as the reactive protein thiol levels, were measured in the soleus (SOL), red gastrocnemius (RG), and white gastrocnemius (WG) muscles of rats. RG showed higher oxygen consumption flow than SOL and WG, while SOL had higher oxygen consumption than WG. SOL showed higher NOX activity, as well as NOX2 and NOX4 mRNA levels, antioxidant enzymatic activities, and reactive protein thiol contents when compared to WG and RG. NOX activity and NOX4 mRNA levels as well as antioxidant enzymatic activities were higher in RG than in WG. Physical exercise increased NOX activity in SOL and RG, specifically NOX2 mRNA levels in RG and NOX4 mRNA levels in SOL. In conclusion, we demonstrated that NOX activity and expression differ according to the skeletal muscle fiber type, as well as antioxidant defense. PMID:27847553

  5. Differential Expression of NADPH Oxidases Depends on Skeletal Muscle Fiber Type in Rats.

    PubMed

    Loureiro, Adriano César Carneiro; do Rêgo-Monteiro, Igor Coutinho; Louzada, Ruy A; Ortenzi, Victor Hugo; de Aguiar, Angélica Ponte; de Abreu, Ewerton Sousa; Cavalcanti-de-Albuquerque, João Paulo Albuquerque; Hecht, Fabio; de Oliveira, Ariclécio Cunha; Ceccatto, Vânia Marilande; Fortunato, Rodrigo S; Carvalho, Denise P

    2016-01-01

    NADPH oxidases (NOX) are important sources of reactive oxygen species (ROS) in skeletal muscle, being involved in excitation-contraction coupling. Thus, we aimed to investigate if NOX activity and expression in skeletal muscle are fiber type specific and the possible contribution of this difference to cellular oxidative stress. Oxygen consumption rate, NOX activity and mRNA levels, and the activity of catalase (CAT), glutathione peroxidase (GPX), and superoxide dismutase (SOD), as well as the reactive protein thiol levels, were measured in the soleus (SOL), red gastrocnemius (RG), and white gastrocnemius (WG) muscles of rats. RG showed higher oxygen consumption flow than SOL and WG, while SOL had higher oxygen consumption than WG. SOL showed higher NOX activity, as well as NOX2 and NOX4 mRNA levels, antioxidant enzymatic activities, and reactive protein thiol contents when compared to WG and RG. NOX activity and NOX4 mRNA levels as well as antioxidant enzymatic activities were higher in RG than in WG. Physical exercise increased NOX activity in SOL and RG, specifically NOX2 mRNA levels in RG and NOX4 mRNA levels in SOL. In conclusion, we demonstrated that NOX activity and expression differ according to the skeletal muscle fiber type, as well as antioxidant defense.

  6. Reduction of type IIb myosin and IIB fibers in tibialis anterior muscle of mini-muscle mice from high-activity lines.

    PubMed

    Bilodeau, Geneviève M; Guderley, Helga; Joanisse, Denis R; Garland, Theodore

    2009-03-01

    Selective breeding of laboratory house mice (Mus domesticus) for high voluntary wheel running has generated four replicate lines that show an almost threefold increase in daily wheel-running distances as compared with four nonselected control lines. An unusual hindlimb "mini-muscle" phenotype (small muscles, increased mitochondrial enzyme levels, disorganized fiber distribution) has increased in frequency in two of the four replicate selected lines. The gene of major effect that accounts for this phenotype is an autosomal recessive that has been mapped to a 2.6335 Mb interval on MMU11, but not yet identified. This study examined the tibialis anterior muscle to determine whether changes in muscle fiber types could explain such modifications in muscle size and properties. Although selected and control lines did not exhibit systematic differences in the fiber types present in the tibialis anterior muscle, as assessed by electrophoresis of myosin heavy chains (MHC) and by histochemistry, mini-muscle mice lacked type IIB fibers and the corresponding MHCs. Mini-muscle tibialis show increased activities of hexokinase and citrate synthase compared with the normally sized muscles, likely the result of the modified fiber types in the muscle. The mini-muscle phenotype is the major means through which selective breeding for high wheel running has modified the functional capacities of the hindlimb muscles, as normally sized tibialis anterior muscles from control and selected lines did not show general differences in their enzymatic capacities, MHC profiles or fiber type composition, with the exception of an elevated hexokinase activity and a reduced GPa activity in the selected lines.

  7. Myostatin regulates fiber-type composition of skeletal muscle by regulating MEF2 and MyoD gene expression.

    PubMed

    Hennebry, Alex; Berry, Carole; Siriett, Victoria; O'Callaghan, Paul; Chau, Linda; Watson, Trevor; Sharma, Mridula; Kambadur, Ravi

    2009-03-01

    Myostatin (Mstn) is a secreted growth factor belonging to the tranforming growth factor (TGF)-beta superfamily. Inactivation of murine Mstn by gene targeting, or natural mutation of bovine or human Mstn, induces the double muscling (DM) phenotype. In DM cattle, Mstn deficiency increases fast glycolytic (type IIB) fiber formation in the biceps femoris (BF) muscle. Using Mstn null ((-/-)) mice, we suggest a possible mechanism behind Mstn-mediated fiber-type diversity. Histological analysis revealed increased type IIB fibers with a concomitant decrease in type IIA and type I fibers in the Mstn(-/-) tibialis anterior and BF muscle. Functional electrical stimulation of Mstn(-/-) BF revealed increased fatigue susceptibility, supporting increased type IIB fiber content. Given the role of myocyte enhancer factor 2 (MEF2) in oxidative type I fiber formation, MEF2 levels in Mstn(-/-) tissue were quantified. Results revealed reduced MEF2C protein in Mstn(-/-) muscle and myoblast nuclear extracts. Reduced MEF2-DNA complex was also observed in electrophoretic mobility-shift assay using Mstn(-/-) nuclear extracts. Furthermore, reduced expression of MEF2 downstream target genes MLC1F and calcineurin were found in Mstn(-/-) muscle. Conversely, Mstn addition was sufficient to directly upregulate MLC promoter-enhancer activity in cultured myoblasts. Since high MyoD levels are seen in fast fibers, we analyzed MyoD levels in the muscle. In contrast to MEF2C, MyoD levels were increased in Mstn(-/-) muscle. Together, these results suggest that while Mstn positively regulates MEF2C levels, it negatively regulates MyoD expression in muscle. We propose that Mstn could regulate fiber-type composition by regulating the expression of MEF2C and MyoD during myogenesis.

  8. Fiber-type susceptibility to eccentric contraction-induced damage of hindlimb-unloaded rat AL muscles

    NASA Technical Reports Server (NTRS)

    Vijayan, K.; Thompson, J. L.; Norenberg, K. M.; Fitts, R. H.; Riley, D. A.

    2001-01-01

    Slow oxidative (SO) fibers of the adductor longus (AL) were predominantly damaged during voluntary reloading of hindlimb unloaded (HU) rats and appeared explainable by preferential SO fiber recruitment. The present study assessed damage after eliminating the variable of voluntary recruitment by tetanically activating all fibers in situ through the motor nerve while applying eccentric (lengthening) or isometric contractions. Muscles were aldehyde fixed and resin embedded, and semithin sections were cut. Sarcomere lesions were quantified in toluidine blue-stained sections. Fibers were typed in serial sections immunostained with antifast myosin and antitotal myosin (which highlights slow fibers). Both isometric and eccentric paradigms caused fatigue. Lesions occurred only in eccentrically contracted control and HU muscles. Fatigue did not cause lesions. HU increased damage because lesioned- fiber percentages within fiber types and lesion sizes were greater than control. Fast oxidative glycolytic (FOG) fibers were predominantly damaged. In no case did damaged SO fibers predominate. Thus, when FOG, SO, and hybrid fibers are actively lengthened in chronically unloaded muscle, FOG fibers are intrinsically more susceptible to damage than SO fibers. Damaged hybrid-fiber proportions ranged between these extremes.

  9. Fiber size, type, and myosin heavy chain content in rhesus hindlimb muscles after 2 weeks at 2 G

    NASA Technical Reports Server (NTRS)

    Tavakol, Morteza; Roy, Roland R.; Kim, Jung A.; Zhong, Hui; Hodgson, John A.; Hoban-Higgins, Tana M.; Fuller, Charles A.; Edgerton, V. Reggie

    2002-01-01

    BACKGROUND: Fiber atrophy and an increase in the percentage of fast fibers have been observed in Rhesus leg muscles after spaceflight. Hypothesis: Hypergravity will result in muscle fiber hypertrophy and an increase in the percentage of slow fibers. METHODS: Open muscle biopsies were obtained from Rhesus soleus, medial gastrocnemius (MG), and tibialis anterior (TA) muscles before and after 14 d of centrifugation (2 G) and in time-matched controls. Cage activity levels were measured by telemetry. RESULTS: Based on monoclonal antibody binding for myosin heavy chains (MHC), the fastest region of soleus contained a higher proportion of type I+II (27 vs. 13%) and had a tendency for a lower proportion of type I (38 vs. 61%, p = 0.10) fibers after than before centrifugation. There was a higher proportion of type I+II fibers in post- vs. pre-2 G (10 vs. 0.6%) MG biopsies. Fiber type distribution and MHC composition were unaffected in the TA. Overall, mean fiber sizes were unaffected by centrifugation. Average cage activity levels were 36% lower during than before 2 G. CONCLUSIONS: Our hypothesis was rejected. The changes in the proportion of fibers expressing type I MHC are the reverse of that expected with chronic loading of extensors and, paradoxically, are similar to changes observed with chronic unloading, such as occurs during spaceflight, in this primate model. The data are consistent with the observed decrease in total daily activity levels.

  10. Mouse skeletal muscle fiber-type specific macroautophagy and muscle wasting is regulated by a Fyn/STAT3/Vps34 signaling pathway

    PubMed Central

    Yamada, Eijiro; Bastie, Claire C.; Koga, Hiroshi; Wang, Yichen; Cuervo, Ana Maria; Pessin, Jeffrey E.

    2012-01-01

    SUMMARY Skeletal muscle atrophy induced by aging (sarcopenia), inactivity and prolonged fasting states (starvation) is predominantly restricted to glycolytic type II muscle fibers and typical spares oxidative type I fibers. However, the mechanisms accounting for muscle fiber type specificity of atrophy have remained enigmatic. In the current study, we that although the Fyn tyrosine kinase activated the mTORC1 signaling complex, it also induced marked atrophy of glycolytic fibers with relatively less effect on oxidative muscle fibers. This was due to inhibition of macroautophagy via an mTORC1-independent but STAT3-dependent reduction in Vps34 protein levels and decreased Vps34/p150/Beclin1/Atg14 complexes. Physiologically, in the fed sate endogenous Fyn kinase activity was increased in glycolytic but not oxidative skeletal muscle. In parallel, Y705-STAT3 phosphorylation increased with decreased Vps34 protein levels. Moreover, fed/starved regulation of Y705-STAT3 phosphorylation and Vps34 protein levels was prevented in skeletal muscle of Fyn null mice. These data demonstrate a novel Fyn/STAT3/Vps34 pathway that is responsible for fiber type specific regulation of macroautophagy and skeletal muscle atrophy. PMID:22745922

  11. Muscle enzyme and fiber type-specific sarcomere protein increases in serum after inertial concentric-eccentric exercise.

    PubMed

    Carmona, G; Guerrero, M; Cussó, R; Padullés, J M; Moras, G; Lloret, M; Bedini, J L; Cadefau, J A

    2015-12-01

    Muscle damage induced by inertial exercise performed on a flywheel device was assessed through the serum evolution of muscle enzymes, interleukin 6, and fiber type-specific sarcomere proteins such as fast myosin (FM) and slow myosin (SM). We hypothesized that a model of muscle damage could be constructed by measuring the evolution of serum concentration of muscle proteins following inertial exercise, according to their molecular weight and the fiber compartment in which they are located. Moreover, by measuring FM and SM, the type of fibers that are affected could be assessed. Serum profiles were registered before and 24, 48, and 144 h after exercise in 10 healthy and recreationally active young men. Creatine kinase (CK) and CK-myocardial band isoenzyme increased in serum early (24 h) and returned to baseline values after 48 h. FM increased in serum late (48 h) and remained elevated 144 h post-exercise. The increase in serum muscle enzymes suggests increased membrane permeability of both fast and slow fibers, and the increase in FM reveals sarcomere disruption as well as increased membrane permeability of fast fibers. Consequently, FM could be adopted as a fiber type-specific biomarker of muscle damage.

  12. Skeletal muscle fiber type composition and performance during repeated bouts of maximal, concentric contractions

    NASA Technical Reports Server (NTRS)

    Colliander, E. B.; Dudley, G. A.; Tesch, P. A.

    1988-01-01

    Force output and fatigue and recovery patterns were studied during intermittent short-term exercise. 27 men performed three bouts of 30 maximal unilateral knee extensions on 2 different occasions. Blood flow was maintained or occluded during recovery periods (60 s). Blood flow was restricted by inflating a pneumatic cuff placed around the proximal thigh. Muscle biopsies from vastus lateralis were analyzed for identification of fast twitch (FT) and slow twitch (ST) fibers and relative FT area. Peak torque decreased during each bout of exercise and more when blood flow was restricted during recovery. Initial peak torque (IPT) and average peak torque (APT) decreased over the three exercise bouts. This response was 3 fold greater without than with blood flow during recovery. IPT and APT decreased more in individuals with mainly FT fibers than in those with mainly ST fibers. It is suggested that performance during repeated bouts of maximal concentric contractions differs between individuals with different fiber type composition. Specifically, in high intensity, intermittent exercise with emphasis on anaerobic energy release a high FT composition may not necessarily be advantageous for performance.

  13. Effects of muscle fiber type on glycolytic potential and meat quality traits in different Tibetan pig muscles and their association with glycolysis-related gene expression.

    PubMed

    Shen, L Y; Luo, J; Lei, H G; Jiang, Y Z; Bai, L; Li, M Z; Tang, G Q; Li, X W; Zhang, S H; Zhu, L

    2015-11-13

    The myosin heavy chain (MyHC) composition, glycolytic potential, mitochondrial content, and gene expression related to energy metabolism were analyzed in eight muscles from Tibetan pigs, to study how meat quality develops in different muscle tissues. The muscles were classified into three clusters, based on MyHC composition: masseter, trapezius, and latissimus dorsi as 'slow-oxidative-type'; psoas major and semimembranosus as 'intermediate-type'; and longissimus dorsi, obliquus externus abdominis, and semitendinosus as 'fast-glycolytic-type'. The 'slow-oxidative-type' muscles had the highest MyHC I and MyHC IIA content (P < 0.01); 'intermediate-type' muscles, the highest MyHC IIx content (P < 0.01); and 'fast-glycolytic-type' muscles, the highest MyHC IIb content (P < 0.01). The pH values measured in 'slow-oxidative-type' muscles were higher than those in the other clusters were; however, the color of 'fast-glycolytic-type' muscles was palest (P < 0.01). Mitochondrial content increased in the order: fast-glycolytic-type < intermediate-type < slow-oxidative-type. In the 'slow-oxidative-type' muscles, the expression levels of genes related to ATP synthesis were higher, but were lower for those related to glycogen synthesis and glycolysis. Mitochondrial content was significantly positively correlated with MyHC I content, but negatively correlated with MyHC IIb content. MyHC I and mitochondrial content were both negatively correlated with glycolytic potential. Overall, muscles used frequently in exercise had a higher proportion of type I fibers. 'Slow-oxidative-type' muscles, rich in type I fibers with higher mitochondrial and lower glycogen and glucose contents, had a higher ATP synthesis efficiency and lower glycolytic capacity, which contributed to their superior meat quality.

  14. Black and White race differences in aerobic capacity, muscle fiber type, and their influence on metabolic processes.

    PubMed

    Ceaser, Tyrone; Hunter, Gary

    2015-05-01

    Obesity is a known risk factor for cardiometabolic disease. Increasing aerobic capacity (VO2max) reduces adiposity, maintains weight, and reduces the risk of developing obesity and cardiometabolic disease. Two major determinants of aerobic capacity are the metabolic properties specific to a particular muscle fiber type and the capacity of the cardiorespiratory system to deliver nutrient-rich content to the muscle. Recent research suggests that some race/ethnic groups, particularly non-Hispanic Black subjects, are predisposed to a reduced VO2max by way of muscle fiber type. Combined with insufficient physical activity, these characteristics place non-Hispanic Black subjects at an increased risk for obesity and other adverse health outcomes when compared with other race/ethnic groups. The purpose of this review was to suggest a model for explaining how skeletal muscle fiber type may contribute to reduced aerobic capacity and obesity among non-Hispanic Black subjects. Our review indicates that metabolic properties of type II skeletal muscle (e.g. reduced oxidative capacity, capillary density) are related to various cardiometabolic diseases. Based on the review, non-Hispanic Black subjects appear to have a lower maximal aerobic capacity and a greater percentage of type II skeletal muscle fibers. Combined with reduced energy expenditure and reduced hemoglobin concentration, non-Hispanic Black subjects may be inherently predisposed to a reduced maximal aerobic capacity compared with non-Hispanic White subjects, thereby increasing the risk for obesity and related metabolic diseases.

  15. Unexpected dependence of RyR1 splice variant expression in human lower limb muscles on fiber-type composition.

    PubMed

    Willemse, Hermia; Theodoratos, Angelo; Smith, Paul N; Dulhunty, Angela F

    2016-02-01

    The skeletal muscle ryanodine receptor Ca(2+) release channel (RyR1), essential for excitation-contraction (EC) coupling, demonstrates a known developmentally regulated alternative splicing in the ASI region. We now find unexpectedly that the expression of the splice variants is closely related to fiber type in adult human lower limb muscles. We examined the distribution of myosin heavy chain isoforms and ASI splice variants in gluteus minimus, gluteus medius and vastus medialis from patients aged 45 to 85 years. There was a strong positive correlation between ASI(+)RyR1 and the percentage of type 2 fibers in the muscles (r = 0.725), and a correspondingly strong negative correlation between the percentages of ASI(+)RyR1 and percentage of type 1 fibers. When the type 2 fiber data were separated into type 2X and type 2A, the correlation with ASI(+)RyR1 was stronger in type 2X fibers (r = 0.781) than in type 2A fibers (r = 0.461). There was no significant correlation between age and either fiber-type composition or ASI(+)RyR1/ASI(-)RyR1 ratio. The results suggest that the reduced expression of ASI(-)RyR1 during development may reflect a reduction in type 1 fibers during development. Preferential expression of ASI(-) RyR1, having a higher gain of in Ca(2+) release during EC coupling than ASI(+)RyR1, may compensate for the reduced terminal cisternae volume, fewer junctional contacts and reduced charge movement in type 1 fibers.

  16. Eccentric contraction-induced injury to type I, IIa, and IIa/IIx muscle fibers of elderly adults.

    PubMed

    Choi, Seung Jun; Lim, Jae-Young; Nibaldi, Eva G; Phillips, Edward M; Frontera, Walter R; Fielding, Roger A; Widrick, Jeffrey J

    2012-02-01

    Muscles of old laboratory rodents experience exaggerated force losses after eccentric contractile activity. We extended this line of inquiry to humans and investigated the influence of fiber myosin heavy chain (MHC) isoform content on the injury process. Skinned muscle fiber segments, prepared from vastus lateralis biopsies of elderly men and women (78 ± 2 years, N = 8), were subjected to a standardized eccentric contraction (strain, 0.25 fiber length; velocity, 0.50 unloaded shortening velocity). Injury was assessed by evaluating pre- and post-eccentric peak Ca(2+)-activated force per fiber cross-sectional area (F (max)). Over 90% of the variability in post-eccentric F (max) could be explained by a multiple linear regression model consisting of an MHC-independent slope, where injury was directly related to pre-eccentric F (max), and MHC-dependent y-intercepts, where the susceptibility to injury could be described as type IIa/IIx fibers > type IIa fibers > type I fibers. We previously reported that fiber type susceptibility to the same standardized eccentric protocol was type IIa/IIx > type IIa = type I for vastus lateralis fibers of 25-year-old adults (Choi and Widrick, Am J Physiol Cell Physiol 299:C1409-C1417, 2010). Modeling combined data sets revealed significant age by fiber type interactions, with post-eccentric F (max) deficits greater for type IIa and type IIa/IIx fibers from elderly vs. young subjects at constant pre-eccentric F (max). We conclude that the resistance of the myofilament lattice to mechanical strain has deteriorated for type IIa and type IIa/IIx, but not for type I, vastus lateralis fibers of elderly adults.

  17. Skeletal muscle capillary density and fiber type are possible determinants of in vivo insulin resistance in man.

    PubMed Central

    Lillioja, S; Young, A A; Culter, C L; Ivy, J L; Abbott, W G; Zawadzki, J K; Yki-Järvinen, H; Christin, L; Secomb, T W; Bogardus, C

    1987-01-01

    We have compared the capillary density and muscle fiber type of musculus vastus lateralis with in vivo insulin action determined by the euglycemic clamp (M value) in 23 Caucasians and 41 Pima Indian nondiabetic men. M value was significantly correlated with capillary density (r = 0.63; P less than or equal to 0.0001), percent type I fibers (r = 0.29; P less than 0.02), and percent type 2B fibers (r = -0.38; P less than 0.003). Fasting plasma glucose and insulin concentrations were significantly negatively correlated with capillary density (r = -0.46, P less than or equal to 0.0001; r = -0.47, P less than or equal to 0.0001, respectively). Waist circumference/thigh circumference ratio was correlated with percent type 1 fibers (r = -0.39; P less than 0.002). These results suggest that diffusion distance from capillary to muscle cells or some associated biochemical change, and fiber type, could play a role in determining in vivo insulin action. The association of muscle fiber type with body fat distribution may indicate that central obesity is only one aspect of a more generalized metabolic syndrome. The data may provide at least a partial explanation for the insulin resistance associated with obesity and for the altered kinetics of insulin action in the obese. PMID:3301899

  18. Multiple isoforms of myofibrillar proteins in crustacean muscle: evidence for two slow fiber types

    SciTech Connect

    Mykles, D.L.

    1986-01-01

    Four distinct patterns of myofibrillar proteins, extracted from fast and slow muscles of the lobster, Homarus americanus, are distinguished by different assemblages of regulatory and contractile protein variants. Multiple isoforms of troponin-T, -I, and -C, paramyosin, and myosin light chains occur in six muscles of the claws and abdomen. Analysis of glycerinated fibers from the claws of lobster and land crab, Gecarcinus lateralis, show that more than one isoform is expressed in a single fiber, forming unique assemblages by which subgroups can be discriminated within the broader categories of fast and slow fibers. 9 refs., 3 figs.

  19. Skeletal muscle myostatin mRNA expression is fiber-type specific and increases during hindlimb unloading

    NASA Technical Reports Server (NTRS)

    Carlson, C. J.; Booth, F. W.; Gordon, S. E.

    1999-01-01

    Transgenic mice lacking a functional myostatin (MSTN) gene demonstrate greater skeletal muscle mass resulting from muscle fiber hypertrophy and hyperplasia (McPherron, A. C., A. M. Lawler, and S. -J. Lee. Nature 387: 83-90, 1997). Therefore, we hypothesized that, in normal mice, MSTN may act as a negative regulator of muscle mass. Specifically, we hypothesized that the predominately slow (type I) soleus muscle, which demonstrates greater atrophy than the fast (type II) gastrocnemius-plantaris complex (Gast/PLT), would show more elevation in MSTN mRNA abundance during hindlimb unloading (HU). Surprisingly, MSTN mRNA was not detectable in weight-bearing or HU soleus muscle, which atrophied 42% by the 7th day of HU in female ICR mice. In contrast, MSTN mRNA was present in weight-bearing Gast/PLT muscle and was significantly elevated (67%) at 1 day but not at 3 or 7 days of HU. However, the Gast/PLT muscle had only atrophied 17% by the 7th day of HU. Because the soleus is composed only of type I and IIa fibers, whereas the Gast/PLT expresses type IId/x and IIb in addition to type I and IIa, it was necessary to perform a more careful analysis of the relationship between MSTN mRNA levels and myosin heavy-chain (MHC) isoform expression (as a marker of fiber type). A significant correlation (r = 0.725, P < 0. 0005) was noted between the percentage of MHC isoform IIb expression and MSTN mRNA abundance in several muscles of the mouse hindlimb. These results indicate that MSTN expression is not strongly associated with muscle atrophy induced by HU; however, it is strongly associated with MHC isoform IIb expression in normal muscle.

  20. Fiber-type composition in the perivertebral musculature of lizards: Implications for the evolution of the diapsid trunk muscles.

    PubMed

    Moritz, Sabine; Schilling, Nadja

    2013-03-01

    The perivertebral musculature of lizards is critical for the stabilization and the mobilization of the trunk during locomotion. Some trunk muscles are also involved in ventilation. This dual function of trunk muscles in locomotion and ventilation leads to a biomechanical conflict in many lizards and constrains their ability to breathe while running ("axial constraint") which likely is reflected by their high anaerobic scope. Furthermore, different foraging and predator-escape strategies were shown to correlate with the metabolic profile of locomotor muscles in lizards. Because knowledge of muscle's fiber-type composition may help to reveal a muscle's functional properties, we investigated the distribution pattern of muscle fiber types in the perivertebral musculature in two small lizard species with a generalized body shape and subjected to the axial constraint (Dipsosaurus dorsalis, Acanthodactylus maculatus) and one species that circumvents the axial constraint by means of gular pumping (Varanus exanthematicus). Additionally, these species differ in their predator-escape and foraging behaviors. Using refined enzyme-histochemical protocols, muscle fiber types were differentiated in serial cross-sections through the trunk, maintaining the anatomical relationships between the skeleton and the musculature. The fiber composition in Dipsosaurus and Acanthodactylus showed a highly glycolytic profile, consistent with their intermittent locomotor style and reliance on anaerobic metabolism during activity. Because early representatives of diapsids resemble these two species in several postcranial characters, we suggest that this glycolytic profile represents the plesiomorphic condition for diapsids. In Varanus, we found a high proportion of oxidative fibers in all muscles, which is in accordance with its high aerobic scope and capability of sustained locomotion.

  1. Transgenic mice expressing mutant Pinin exhibit muscular dystrophy, nebulin deficiency and elevated expression of slow-type muscle fiber genes

    SciTech Connect

    Wu, Hsu-Pin; Hsu, Shu-Yuan; Wu, Wen-Ai; Hu, Ji-Wei; Ouyang, Pin

    2014-01-03

    Highlights: •Pnn CCD domain functions as a dominant negative mutant regulating Pnn expression and function. •Pnn CCD mutant Tg mice have a muscle wasting phenotype during development and show dystrophic histological features. •Pnn mutant muscles are susceptible to slow fiber type gene transition and NEB reduction. •The Tg mouse generated by overexpression of the Pnn CCD domain displays many characteristics resembling NEB{sup +/−} mice. -- Abstract: Pinin (Pnn) is a nuclear speckle-associated SR-like protein. The N-terminal region of the Pnn protein sequence is highly conserved from mammals to insects, but the C-terminal RS domain-containing region is absent in lower species. The N-terminal coiled-coil domain (CCD) is, therefore, of interest not only from a functional point of view, but also from an evolutionarily standpoint. To explore the biological role of the Pnn CCD in a physiological context, we generated transgenic mice overexpressing Pnn mutant in skeletal muscle. We found that overexpression of the CCD reduces endogenous Pnn expression in cultured cell lines as well as in transgenic skeletal muscle fibers. Pnn mutant mice exhibited reduced body mass and impaired muscle function during development. Mutant skeletal muscles show dystrophic histological features with muscle fibers heavily loaded with centrally located myonuclei. Expression profiling and pathway analysis identified over-representation of genes in gene categories associated with muscle contraction, specifically those related to slow type fiber. In addition nebulin (NEB) expression level is repressed in Pnn mutant skeletal muscle. We conclude that Pnn downregulation in skeletal muscle causes a muscular dystrophic phenotype associated with NEB deficiency and the CCD domain is incapable of replacing full length Pnn in terms of functional capacity.

  2. Adrenergic control of vascular resistance varies in muscles composed of different fiber types: influence of the vascular endothelium

    PubMed Central

    Armstrong, Robert B.; Delp, Michael D.

    2011-01-01

    The influence of the sympathetic nervous system (SNS) upon vascular resistance is more profound in muscles comprised predominately of low-oxidative type IIB vs. high-oxidative type I fiber types. However, within muscles containing high-oxidative type IIA and IIX fibers, the role of the SNS on vasomotor tone is not well established. The purpose of this study was to examine the influence of sympathetic neural vasoconstrictor tone in muscles composed of different fiber types. In adult male rats, blood flow to the red and white portions of the gastrocnemius (GastRed and GastWhite, respectively) and the soleus muscle was measured pre- and postdenervation. Resistance arterioles from these muscles were removed, and dose responses to α1-phenylephrine or α2-clonidine adrenoreceptor agonists were determined with and without the vascular endothelium. Denervation resulted in a 2.7-fold increase in blood flow to the soleus and GastRed and an 8.7-fold increase in flow to the GastWhite. In isolated arterioles, α2-mediated vasoconstriction was greatest in GastWhite (∼50%) and less in GastRed (∼31%) and soleus (∼17%); differences among arterioles were abolished with the removal of the endothelium. There was greater sensitivity to α1-mediated vasoconstriction in the GastWhite and GastRed vs. the soleus, which was independent of whether the endothelium was present. These data indicate that 1) control of vascular resistance by the SNS in high-oxidative, fast-twitch muscle is intermediate to that of low-oxidative, fast-twitch and high-oxidative, slow-twitch muscles; and 2) the ability of the SNS to control blood flow to low-oxidative type IIB muscle appears to be mediated through postsynaptic α1- and α2-adrenoreceptors on the vascular smooth muscle. PMID:21677269

  3. Human Muscle Fiber

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The stimulus of gravity affects RNA production, which helps maintain the strength of human muscles on Earth (top), as seen in this section of muscle fiber taken from an astronaut before spaceflight. Astronauts in orbit and patients on Earth fighting muscle-wasting diseases need countermeasures to prevent muscle atrophy, indicated here with white lipid droplets (bottom) in the muscle sample taken from the same astronaut after spaceflight. Kerneth Baldwin of the University of California, Irvine, is conducting research on how reducing the stimulus of gravity affects production of the RNA that the body uses as a blueprint for making muscle proteins. Muscle proteins are what give muscles their strength, so when the RNA blueprints aren't available for producing new proteins to replace old ones -- a situation that occurs in microgravity -- the muscles atrophy. When the skeletal muscle system is exposed to microgravity during spaceflight, the muscles undergo a reduced mass that translates to a reduction in strength. When this happens, muscle endurance decreases and the muscles are more prone to injury, so individuals could have problems in performing extravehicular activity [space walks] or emergency egress because their bodies are functionally compromised.

  4. Sprint training effects on muscle myoglobin, enzymes, fiber types, and blood lactate.

    PubMed

    Jacobs, I; Esbjörnsson, M; Sylvén, C; Holm, I; Jansson, E

    1987-08-01

    The purpose of this study was to determine if changes in intra-muscular myoglobin concentration accompany histochemical and enzymatic adaptations to supra-maximal exercise training. Subjects were assigned to either a training group (N = 11), who trained 2 to 3 times weekly for 6 wk, or a control group (N = 6). Training progressed from two 15-s and two 30-s "all-out" sprints on a cycle ergometer during week 1 to six 15-s and six 30-s bouts per session during week 6. The Wingate test was performed before and after the 6 wk, but performance variables were not changed in either group. In the training group, peak lactate after the Wingate test was significantly higher after training. No significant changes in enzyme activities, myoglobin concentration, or fiber-type frequency were observed in the control group. In contrast, in the training group, the percent fast twitch oxidative fibers increased, myoglobin decreased, and both citrate synthase and phosphofructokinase activities increased (P less than 0.05). The results suggest that muscle myoglobin concentration is not increased by 6 wk of supra-maximal exercise training and that such training induces cellular adaptations without accompanying performance changes. Alternatively, the Wingate test is not a sensitive test of adaptations to the training.

  5. Lack of correspondence between histochemical and structural fiber typing in antennal muscles of the rock lobster Palinurus vulgaris.

    PubMed

    Rossi-Durand, C

    1991-01-01

    1. Sarcomere lengths and fine structure were examined in three histochemical fiber types of antennal muscles of the rock lobster. 2. Sarcomere lengths are distributed over a continuum of values from 6.5 to 19 microns. 3. Although a correlation between ATPase activity and sarcomere length is demonstrated, fibers with high ATPase activity do not have the sarcomere length typical of fast contracting fibers. 4. These fibers deviated from the typical fast structure in having long sarcomeres (greater than 6.5 microns) and in having some unusual ultrastructural characteristics (absence of the H-band, presence of Z-tubules, high thin to thick ratio, 5:1) associated with other more classical features. 5. This finding demonstrates that sarcomere length measurements do not always accurately predict the physiological performance of a single muscle fiber. 6. The fiber type composition of two antagonistic antennal muscles is compared and the functional significance of the results is discussed with respect to their role in behavior.

  6. Early detection of denervated muscle fibers in hindlimb muscles after sciatic nerve transection in wild type mice and in the G93A mouse model of amyotrophic lateral sclerosis.

    PubMed

    Gordon, T; Ly, V; Hegedus, J; Tyreman, N

    2009-02-01

    The cell adhesion molecule N-CAM is localized to the adult neuromuscular junction but is also expressed in the extrajunctional membrane of denervated muscles concurrent with extrajunctional acetylcholine receptors. Here we used N-CAM immunohistochemistry to determine whether we could detect early denervation in hindlimb muscles of the G93A transgenic mouse model of amyotrophic lateral sclerosis (ALS). In denervated wild type mouse muscles, N-CAM immunoreactivity on the sarcolemma of all fiber types and within the sarcoplasm of only type IIA fibers was detected at day 2: approximately 30% of the muscle fibers in cross-section were fully circumscribed by N-CAM immunoreactivity and approximately 25% of fibers were incompletely circumscribed. The proportion of the latter fibers remained constant over the next 8 days as the proportions of the former fibers increased exponentially. Thereafter, fully circumscribed muscle fibers increased to a maximum by 30 days with a concomitant fall in the incompletely circumscribed fibers. Hence, early muscle denervation was detected by the incomplete circumscription of fiber membranes by N-CAM immunoreactivity with full circumscription and intracellular localization indicating more long-term denervation. In the G93A transgenic mouse, rapid denervation of fast-twitch muscles was readily detected by a corresponding proportion of muscle fibers in cross-section with positive N-CAM immunoreactivity. The proportions of incompletely and completely circumscribed muscle fibers corresponded well with the rate of decline in intact motor units and reduced muscle contractile forces. Progressively more fully circumscribed muscle fibers became evident with age. We conclude that the N-CAM immunoreactivity on muscle fiber membranes in muscle cross-sections provides a sensitive means of detecting early muscle fiber denervation.

  7. Reduced Appendicular Lean Body Mass, Muscle Strength, and Size of Type II Muscle Fibers in Patients with Spondyloarthritis versus Healthy Controls: A Cross-Sectional Study

    PubMed Central

    2016-01-01

    Introduction. The purpose of this study was to investigate body composition, muscle function, and muscle morphology in patients with spondyloarthritis (SpA). Methods. Ten male SpA patients (mean ± SD age 39 ± 4.1 years) were compared with ten healthy controls matched for sex, age, body mass index, and self-reported level of physical exercise. Body composition was measured by dual energy X-ray absorptiometry. Musculus quadriceps femoris (QF) strength was assessed by maximal isometric contractions prior to test of muscular endurance. Magnetic resonance imaging of QF was used to measure muscle size and calculate specific muscle strength. Percutaneous needle biopsy samples were taken from m. vastus lateralis. Results. SpA patients presented with significantly lower appendicular lean body mass (LBM) (p = 0.02), but there was no difference in bone mineral density, fat mass, or total LBM. Absolute QF strength was significantly lower in SpA patients (p = 0.03) with a parallel trend for specific strength (p = 0.08). Biopsy samples from the SpA patients revealed significantly smaller cross-sectional area (CSA) of type II muscle fibers (p = 0.04), but no difference in CSA type I fibers. Conclusions. Results indicate that the presence of SpA disease is associated with reduced appendicular LBM, muscle strength, and type II fiber CSA. PMID:27672678

  8. Reduced Appendicular Lean Body Mass, Muscle Strength, and Size of Type II Muscle Fibers in Patients with Spondyloarthritis versus Healthy Controls: A Cross-Sectional Study.

    PubMed

    Røren Nordén, Kristine; Dagfinrud, Hanne; Løvstad, Amund; Raastad, Truls

    Introduction. The purpose of this study was to investigate body composition, muscle function, and muscle morphology in patients with spondyloarthritis (SpA). Methods. Ten male SpA patients (mean ± SD age 39 ± 4.1 years) were compared with ten healthy controls matched for sex, age, body mass index, and self-reported level of physical exercise. Body composition was measured by dual energy X-ray absorptiometry. Musculus quadriceps femoris (QF) strength was assessed by maximal isometric contractions prior to test of muscular endurance. Magnetic resonance imaging of QF was used to measure muscle size and calculate specific muscle strength. Percutaneous needle biopsy samples were taken from m. vastus lateralis. Results. SpA patients presented with significantly lower appendicular lean body mass (LBM) (p = 0.02), but there was no difference in bone mineral density, fat mass, or total LBM. Absolute QF strength was significantly lower in SpA patients (p = 0.03) with a parallel trend for specific strength (p = 0.08). Biopsy samples from the SpA patients revealed significantly smaller cross-sectional area (CSA) of type II muscle fibers (p = 0.04), but no difference in CSA type I fibers. Conclusions. Results indicate that the presence of SpA disease is associated with reduced appendicular LBM, muscle strength, and type II fiber CSA.

  9. Transcriptome signature of resistance exercise adaptations: mixed muscle and fiber type specific profiles in young and old adults

    PubMed Central

    Raue, Ulrika; Trappe, Todd A.; Estrem, Shawn T.; Qian, Hui-Rong; Helvering, Leah M.; Smith, Rosamund C.

    2012-01-01

    This investigation examined the effects of acute resistance exercise (RE), progressive resistance training (PRT), and age on the human skeletal muscle Transcriptome. Two cohorts of young and old adults [study A: 24 yr, 84 yr (n = 28); study B: 25 yr, 78 yr (n = 36)] were studied. Vastus lateralis biopsies were obtained pre- and 4 h post-RE in conjunction with the 1st and 36th (last) training session as part of a 12-wk PRT program in study A, whereas biopsies were obtained in the basal untrained state in study B. Additionally, the muscle fiber type specific (MHC I and MHC IIa) Transcriptome response to RE was examined in a subset of young and old women from study A. Transcriptome profiling was performed using HG U133 Plus 2.0 Arrays. The main findings were 1) there were 661 genes affected by RE during the 1st and 36th training bout that correlated with gains in muscle size and strength with PRT (termed the Transcriptome signature of resistance exercise adaptations); 2) the RE gene response was most pronounced in fast-twitch (MHC IIa) muscle fibers and provided additional insight into the skeletal muscle biology affected by RE; 3) skeletal muscle of young adults is more responsive to RE at the gene level compared with old adults and age also affected basal level skeletal muscle gene expression. These skeletal muscle Transcriptome findings provide further insight into the molecular basis of sarcopenia and the impact of resistance exercise at the mixed muscle and fiber type specific level. PMID:22302958

  10. FoxO1 regulates muscle fiber-type specification and inhibits calcineurin signaling during C2C12 myoblast differentiation.

    PubMed

    Yuan, Yuan; Shi, Xin-e; Liu, Yue-guang; Yang, Gong-she

    2011-02-01

    Adult skeletal muscle fibers can be categorized into slow-oxidative and fast-glycolytic subtypes based on specialized metabolic and contractile properties. The Forkhead box O1 (FoxO1) transcription factor governs muscle growth, metabolism, and cell differentiation, and has been shown to be involved in regulating muscle fiber type specification. However, to date, the mechanism behind FoxO1-mediated fiber type diversity is still unclear. In this article, FoxO1 being expressed preferentially in fast twitch fiber enriched muscles is reported. Moreover, the autors also detected that FoxO1 expression decreased in both fast and slow muscles from mice undergoing endurance exercise which induced a fast-to-slow fiber type transition. Using C2C12 myoblast, constitutively active FoxO1 mutant altered the proportion of muscle fiber type composition toward a fast-glycolytic phenotype and attenuated calcineurin phosphatase activity. In addition, a transcriptionally inactive FoxO1 by resveratrol triggered the expression of genes related to slow-oxidative muscle but not sufficient to induce a complete slow fiber transformation. Taken together, these results suggest that FoxO1 up-regulates fast fiber-type formation and down-regulates muscle oxidative capacity at least in part through inhibition of the calcineurin pathway.

  11. Physiologic, metabolic, and muscle fiber type characteristics of musculus uvulae in sleep apnea hypopnea syndrome and in snorers.

    PubMed Central

    Sériès, F; Côté, C; Simoneau, J A; Gélinas, Y; St Pierre, S; Leclerc, J; Ferland, R; Marc, I

    1995-01-01

    Upper airway dilator muscles play an important role in the pathophysiology of sleep apnea hypopnea syndrome (SAHS). The mechanical and structural characteristics of these muscles remain unknown. The aim of this study was to compare the physiologic, metabolic, and fiber type characteristics of one upper airway dilator muscle (musculus uvulae, MU) in 11 SAHS and in seven nonapneic snorers. The different analyses were done on MU obtained during uvulo-palato-pharyngoplasty. Snorers and SAHS differed only in their apnea + hypopnea indices (11.5 +/- 5.9 and 34.2 +/- 14.6/h, respectively, mean +/- SD). Absolute twitch and tetanic tension production of MU was significantly greater in SAHS than in snorers while the fatigability index was similar in the two groups. Protein content and anaerobic enzyme activities of MU were significantly greater in SAHS than in snorers; no difference was observed for aerobic enzyme activities. The total muscle fiber cross-sectional area of MU was significantly higher in SAHS (2.2 +/- 0.9 mm2) than in snorers (1.1 +/- 0.7 mm2). The surface occupied by type IIA muscle fibers of MU was larger in SAHS (2.00 +/- 0.96) than in snorers (0.84 +/- 0.63 mm2). We conclude that the capacity for tension production and the anaerobic metabolic activity of MU are greater in SAHS than in snorers. PMID:7814616

  12. Use it or Lose It: Tonic Activity of Slow Motoneurons Promotes Their Survival and Preferentially Increases Slow Fiber-Type Groupings in Muscles of Old Lifelong Recreational Sportsmen

    PubMed Central

    Mosole, Simone; Carraro, Ugo; Kern, Helmut; Loefler, Stefan; Zampieri, Sandra

    2016-01-01

    Histochemistry, immuno-histochemistry, gel electrophoresis of single muscle fibers and electromyography of aging muscles and nerves suggest that: i) denervation contributes to muscle atrophy, ii) impaired mobility accelerates the process, and iii) lifelong running protects against loss of motor units. Recent corroborating results on the muscle effects of Functional Electrical Stimulation (FES) of aged muscles will be also mentioned, but we will in particular discuss how and why a lifelong increased physical activity sustains reinnervation of muscle fibers. By analyzing distribution and density of muscle fibers co-expressing fast and slow Myosin Heavy Chains (MHC) we are able to distinguish the transforming muscle fibers due to activity related plasticity, to those that adapt muscle fiber properties to denervation and reinnervation. In muscle biopsies from septuagenarians with a history of lifelong high-level recreational activity we recently observed in comparison to sedentary seniors: 1. decreased proportion of small-size angular myofibers (denervated muscle fibers); 2. considerable increase of fiber-type groupings of the slow type (reinnervated muscle fibers); 3. sparse presence of muscle fibers co-expressing fast and slow MHC. Immuno-histochemical characteristics fluctuate from those with scarce fiber-type modulation and groupings to almost complete transformed muscles, going through a process in which isolated fibers co-expressing fast and slow MHC fill the gaps among fiber groupings. Data suggest that lifelong high-level exercise allows the body to adapt to the consequences of the age-related denervation and that it preserves muscle structure and function by saving otherwise lost muscle fibers through recruitment to different slow motor units. This is an opposite behavior of that described in long term denervated or resting muscles. These effects of lifelong high level activity seems to act primarily on motor neurons, in particular on those always more active

  13. Block of single L-type Ca2+ channels in skeletal muscle fibers by aminoglycoside antibiotics

    PubMed Central

    1996-01-01

    The activity of single L-type Ca2+ channels was recorded from cell- attached patches on acutely isolated skeletal muscle fibers from the mouse. The experiments were concerned with the mechanism by which aminoglycoside antibiotics inhibit ion flow through the channel. Aminoglycosides produced discrete fluctuations in the single-channel current when added to the external solution. The blocking kinetics could be described as a simple bimolecular reaction between an aminoglycoside molecule and the open channel. The blocking rate was found to be increased when either the membrane potential was made more negative or the concentration of external permeant ion was reduced. Both of these effects are consistent with a blocking site that is located within the channel pore. Other features of block, however, were incompatible with a simple pore blocking mechanism. Hyperpolarization enhanced the rate of unblocking, even though an aminoglycoside molecule must dissociate from its binding site in the channel toward the external solution against the membrane field. Raising the external permeant ion concentration also enhanced the rate of unblocking. This latter finding suggests that aminglycoside affinity is modified by repulsive interactions that arise when the pore is simultaneously occupied by a permeant ion and an aminoglycoside molecule. PMID:8868052

  14. Single muscle fiber adaptations with marathon training.

    PubMed

    Trappe, Scott; Harber, Matthew; Creer, Andrew; Gallagher, Philip; Slivka, Dustin; Minchev, Kiril; Whitsett, David

    2006-09-01

    The purpose of this investigation was to characterize the effects of marathon training on single muscle fiber contractile function in a group of recreational runners. Muscle biopsies were obtained from the gastrocnemius muscle of seven individuals (22 +/- 1 yr, 177 +/- 3 cm, and 68 +/- 2 kg) before, after 13 wk of run training, and after 3 wk of taper. Slow-twitch myosin heavy chain [(MHC) I] and fast-twitch (MHC IIa) muscle fibers were analyzed for size, strength (P(o)), speed (V(o)), and power. The run training program led to the successful completion of a marathon (range 3 h 56 min to 5 h 35 min). Oxygen uptake during submaximal running and citrate synthase activity were improved (P < 0.05) with the training program. Muscle fiber size declined (P < 0.05) by approximately 20% in both fiber types after training. P(o) was maintained in both fiber types with training and increased (P < 0.05) by 18% in the MHC IIa fibers after taper. This resulted in >60% increase (P < 0.05) in force per cross-sectional area in both fiber types. Fiber V(o) increased (P < 0.05) by 28% in MHC I fibers with training and was unchanged in MHC IIa fibers. Peak power increased (P < 0.05) in MHC I and IIa fibers after training with a further increase (P < 0.05) in MHC IIa fiber power after taper. These data show that marathon training decreased slow-twitch and fast-twitch muscle fiber size but that it maintained or improved the functional profile of these fibers. A taper period before the marathon further improved the functional profile of the muscle, which was targeted to the fast-twitch muscle fibers.

  15. Micro-RNA expression in muscle and fiber morphometry in myotonic dystrophy type 1.

    PubMed

    Fritegotto, Chiara; Ferrati, Chiara; Pegoraro, Valentina; Angelini, Corrado

    2017-04-01

    We aimed to explore the cellular action of micro-RNAs that are non-coding-RNAs modulating gene expression, whose expression is dysregulated in myotonic dystrophy (DM1). Basic procedure was to measure the levels of muscle-specific myo-miRNAs (miR-1, miR-133a/b, miR-206) in muscle of 12 DM1 patients. Muscle fiber morphometry and a new grading of histopathological severity score were used to compare specific myo-miRNA level and fiber atrophy. We found that the levels of miR-1 and miR-133a/b were significantly decreased, while miR-206 was significantly increased as compared to controls. The histopathological score did not significantly correlate with the levels of myo-miRNAs, even if the lowest levels of miRNA-1 and miRNA-133a/b, and the highest levels of miRNA-206 were observed in patients with either severe histopathological scores or long disease duration. The histopathological score was inversely correlated with disease duration. Nowadays that DM1 muscle biopsies are scanty, since patients are usually diagnosed by genetic analysis, our study offers a unique opportunity to present miRNA expression profiles in muscle and correlate them to muscle morphology in this rare multisystem disorder. Our molecular and morphologic data suggest a post-transcriptional regulatory action of myo-miRNA in DM1, highlighting their potential role as biomarkers of muscle plasticity.

  16. Ca2+ release in muscle fibers expressing R4892W and G4896V type 1 ryanodine receptor disease mutants.

    PubMed

    Lefebvre, Romain; Legrand, Claude; Groom, Linda; Dirksen, Robert T; Jacquemond, Vincent

    2013-01-01

    The large and rapidly increasing number of potentially pathological mutants in the type 1 ryanodine receptor (RyR1) prompts the need to characterize their effects on voltage-activated sarcoplasmic reticulum (SR) Ca(2+) release in skeletal muscle. Here we evaluated the function of the R4892W and G4896V RyR1 mutants, both associated with central core disease (CCD) in humans, in myotubes and in adult muscle fibers. For both mutants expressed in RyR1-null (dyspedic) myotubes, voltage-gated Ca(2+) release was absent following homotypic expression and only partially restored following heterotypic expression with wild-type (WT) RyR1. In muscle fibers from adult WT mice, both mutants were expressed in restricted regions of the fibers with a pattern consistent with triadic localization. Voltage-clamp-activated confocal Ca(2+) signals showed that fiber regions endowed with G4896V-RyR1s exhibited an ∼30% reduction in the peak rate of SR Ca(2+) release, with no significant change in SR Ca(2+) content. Immunostaining revealed no associated change in the expression of either α1S subunit (Cav1.1) of the dihydropyridine receptor (DHPR) or type 1 sarco(endo)plasmic reticulum Ca(2+) ATPase (SERCA1), indicating that the reduced Ca(2+) release resulted from defective RyR1 function. Interestingly, in spite of robust localized junctional expression, the R4892W mutant did not affect SR Ca(2+) release in adult muscle fibers, consistent with a low functional penetrance of this particular CCD-associated mutant.

  17. Eight weeks of ballistic exercise improves power independently of changes in strength and muscle fiber type expression.

    PubMed

    Winchester, Jason B; McBride, Jeffrey M; Maher, Margaret A; Mikat, Richard P; Allen, Brian K; Kline, Dennis E; McGuigan, Michael R

    2008-11-01

    This study investigated the effects of ballistic resistance training and strength training on muscle fiber composition, peak force (PF), maximal strength, and peak power (PP). Fourteen males (age = 21.3 +/- 2.9, body mass = 77.8 +/- 10.1 kg) with 3 months of resistance training experience completed the study. Subjects were tested pre and post for their squat one-repetition maximum (1RM) and PP in the jump squat (JS). Peak force and rate of force development (RFD) were tested during an isometric midthigh pull. Muscle biopsies were obtained from the vastus lateralis for analysis of muscle fiber type expression. Subjects were matched for strength and then randomly selected into either training (T) or control (C) groups. Group T performed 8 weeks of JS training using a periodized program with loading between 26 and 48% of 1RM, 3 days per week. Group T showed significant improvement in PP from 4088.9 +/- 520.6 to 5737.6 +/- 651.8 W. Rate of force development improved significantly in group T from 12687.5 +/- 4644.0 to 25343.8 +/- 12614.4 N x s(-1). PV improved significantly from 1.59 +/- 0.41 to 2.11 +/- 0.75 m x s(-1). No changes occurred in PF, 1RM, or muscle fiber type expression for group T. No changes occurred in any variables in group C. The results of this study indicate that using ballistic resistance exercise is an effective method for increasing PP and RFD independently of changes in maximum strength (1RM, PF), and those increases are a result of factors other than changes in muscle fiber type expression.

  18. The Relationship between Muscle Fiber Type-Specific PGC-1α Content and Mitochondrial Content Varies between Rodent Models and Humans

    PubMed Central

    Gouspillou, Gilles; Sgarioto, Nicolas; Norris, Brandon; Barbat-Artigas, Sébastien; Aubertin-Leheudre, Mylène; Morais, Jose A.; Burelle, Yan; Taivassalo, Tanja; Hepple, Russell T.

    2014-01-01

    PGC-1α regulates critical processes in muscle physiology, including mitochondrial biogenesis, lipid metabolism and angiogenesis. Furthermore, PGC-1α was suggested as an important regulator of fiber type determination. However, whether a muscle fiber type-specific PGC-1α content exists, whether PGC-1α content relates to basal levels of mitochondrial content, and whether such relationships are preserved between humans and classically used rodent models are all questions that have been either poorly addressed or never investigated. To address these issues, we investigated the fiber type-specific content of PGC-1α and its relationship to basal mitochondrial content in mouse, rat and human muscles using in situ immunolabeling and histochemical methods on muscle serial cross-sections. Whereas type IIa fibers exhibited the highest PGC-1α in all three species, other fiber types displayed a hierarchy of type IIx>I>IIb in mouse, type I = IIx> IIb in rat, and type IIx>I in human. In terms of mitochondrial content, we observed a hierarchy of IIa>IIx>I>IIb in mouse, IIa >I>IIx> IIb in rat, and I>IIa> IIx in human skeletal muscle. We also found in rat skeletal muscle that type I fibers displayed the highest capillarization followed by type IIa >IIx>IIb. Finally, we found in human skeletal muscle that type I fibers display the highest lipid content, followed by type IIa>IIx. Altogether, our results reveal that (i) the fiber type-specific PGC-1α and mitochondrial contents were only matched in mouse, (ii) the patterns of PGC-1α and mitochondrial contents observed in mice and rats do not correspond to that seen in humans in several respects, and (iii) the classical phenotypes thought to be regulated by PGC-1α do not vary exclusively as a function of PGC-1α content in rat and human muscles. PMID:25121500

  19. Effects of Mechanical Overloading on the Properties of Soleus Muscle Fibers, with or without Damage in MDX and Wild Type Mice

    NASA Astrophysics Data System (ADS)

    Terada, Masahiro; Kawano, Fuminori; Ohira, Takashi; Oke, Yoshihiko; Nakai, Naoya; Ohira, Yoshinobu

    2008-06-01

    Effects of mechanical overloading on the characteristics of regenerating or not-regenerating soleus muscle fibers were studied. The muscle fibers of mdx mice were characterized by the localization of myonuclei. Muscle damage was also induced in wild type (WT) mice by injection of cardiotoxin (CTX) into soleus muscle. Overloading was applied for 14 days to the left soleus muscle in mdx and intact and CTX-injected WT mice by removing the distal tendons of plantaris and gastrocnemius muscles. The contralateral muscle served as the normal control. These animals were then allowed ambulation recovery in the cage. Central myonuclei were noted in many fibers of mdx and CTX-injected mice with or without overloading. In general, the fibers with central nuclei were considered as regenerating fibers. The fibers with more central nuclei were increased in mdx mice, but the fibers with more peripheral nuclei were increased in CTX-injected WT mice by overloading. The muscle satellite cells, neuromuscular junctions (NMJ), and myonuclei were stained. Most of the properties, such as number of myonuclei and satellite cells, size of NMJ, and fiber length, were not influenced by mechanical overloading in all mice. Approximately 0.6% branched fibers were seen in the intact soleus of mdx mice, although these fibers were not detected in WT mice. However, the percentage of these fibers was increased by overloading especially in mdx mice (~50% vs. ~2.5% in WT). In CTX-injected WT mice, these fibers were ~15% with or without overloading. The fiber cross sectional area in normal WT, but not in mdx and CTX-injected WT mice, was increased by overloading (p<0.05). These results suggested that the functional overload induced muscle damage in mdx mice, but promoted the regeneration in CTX-injected WT mice.

  20. Improvement of Endurance Based on Muscle Fiber-Type Composition by Treatment with Dietary Apple Polyphenols in Rats.

    PubMed

    Mizunoya, Wataru; Miyahara, Hideo; Okamoto, Shinpei; Akahoshi, Mariko; Suzuki, Takahiro; Do, Mai-Khoi Q; Ohtsubo, Hideaki; Komiya, Yusuke; Lan, Mu; Waga, Toshiaki; Iwata, Akira; Nakazato, Koichi; Ikeuchi, Yoshihide; Anderson, Judy E; Tatsumi, Ryuichi

    2015-01-01

    A recent study demonstrated a positive effect of apple polyphenol (APP) intake on muscle endurance of young-adult animals. While an enhancement of lipid metabolism may be responsible, in part, for the improvement, the contributing mechanisms still need clarification. Here we show that an 8-week intake of 5% (w/w) APP in the diet, up-regulates two features related to fiber type: the ratio of myosin heavy chain (MyHC) type IIx/IIb and myoglobin protein expression in plantaris muscle of 9-week-old male Fischer F344 rats compared to pair-fed controls (P < 0.05). Results were demonstrated by our SDS-PAGE system specialized for MyHC isoform separation and western blotting of whole muscles. Animal-growth profiles (food intake, body-weight gain, and internal-organ weights) did not differ between the control and 5% APP-fed animals (n = 9/group). Findings may account for the increase in fatigue resistance of lower hind limb muscles, as evidenced by a slower decline in the maximum isometric planter-flexion torque generated by a 100-s train of electrical stimulation of the tibial nerve. Additionally, the fatigue resistance was lower after 8 weeks of a 0.5% APP diet than after 5% APP, supporting an APP-dose dependency of the shift in fiber-type composition. Therefore, the present study highlights a promising contribution of dietary APP intake to increasing endurance based on fiber-type composition in rat muscle. Results may help in developing a novel strategy for application in animal sciences, and human sports and age-related health sciences.

  1. Improvement of Endurance Based on Muscle Fiber-Type Composition by Treatment with Dietary Apple Polyphenols in Rats

    PubMed Central

    Okamoto, Shinpei; Akahoshi, Mariko; Suzuki, Takahiro; Do, Mai-Khoi Q.; Ohtsubo, Hideaki; Komiya, Yusuke; Lan, Mu; Waga, Toshiaki; Iwata, Akira; Nakazato, Koichi; Ikeuchi, Yoshihide; Anderson, Judy E.; Tatsumi, Ryuichi

    2015-01-01

    A recent study demonstrated a positive effect of apple polyphenol (APP) intake on muscle endurance of young-adult animals. While an enhancement of lipid metabolism may be responsible, in part, for the improvement, the contributing mechanisms still need clarification. Here we show that an 8-week intake of 5% (w/w) APP in the diet, up-regulates two features related to fiber type: the ratio of myosin heavy chain (MyHC) type IIx/IIb and myoglobin protein expression in plantaris muscle of 9-week-old male Fischer F344 rats compared to pair-fed controls (P < 0.05). Results were demonstrated by our SDS-PAGE system specialized for MyHC isoform separation and western blotting of whole muscles. Animal-growth profiles (food intake, body-weight gain, and internal-organ weights) did not differ between the control and 5% APP-fed animals (n = 9/group). Findings may account for the increase in fatigue resistance of lower hind limb muscles, as evidenced by a slower decline in the maximum isometric planter-flexion torque generated by a 100-s train of electrical stimulation of the tibial nerve. Additionally, the fatigue resistance was lower after 8 weeks of a 0.5% APP diet than after 5% APP, supporting an APP-dose dependency of the shift in fiber-type composition. Therefore, the present study highlights a promising contribution of dietary APP intake to increasing endurance based on fiber-type composition in rat muscle. Results may help in developing a novel strategy for application in animal sciences, and human sports and age-related health sciences. PMID:26222548

  2. De novo synthesis of purine nucleotides in different fiber types of rat skeletal muscle

    SciTech Connect

    Tullson, P.C.; John-Alder, H.; Hood, D.A.; Terjung, R.L.

    1986-03-01

    The contribution of de novo purine nucleotide synthesis to nucleotide metabolism in skeletal muscles is not known. The authors have determined rates of de novo synthesis in soleus (slow-twitch red), red gastrocnemius (fast-twitch red), and white gastrocnemius (fast-twitch white) using the perfused rat hindquarter. /sup 14/C glycine incorporation into ATP was linear after 1 and 2 hours of perfusion with 0.2 mM added glycine. The intracellular (I) and extracellular (E) specific activity of /sup 14/C glycine was determined by HPLC of phenylisothiocyanate derivatives of neutralized PCA extracts. The rates of de novo synthesis when expressed relative to muscle ATP content show slow and fast-twitch red muscles to be similar and about twice as great as fast-twitch white muscles. This could represent a greater turnover of the adenine nucleotide pool in more oxidative red muscle types.

  3. Long-term delivery of FGF-6 changes the fiber type and fatigability of muscle reinnervated from embryonic neurons transplanted into adult rat peripheral nerve.

    PubMed

    Grumbles, Robert M; Casella, Gizelda T B; Rudinsky, Michelle J; Wood, Patrick M; Sesodia, Sanjay; Bent, Melissa; Thomas, Christine K

    2007-07-01

    Motoneuron death leads to muscle denervation and atrophy. Transplantation of embryonic neurons into peripheral nerves results in reinnervation and provides a strategy to rescue muscles from atrophy independent of neuron replacement in a damaged or diseased spinal cord. But the count of regenerating axons always exceeds the number of motor units in this model, so target-derived trophic factor levels may limit reinnervation. Our aim was to examine whether long-term infusion of fibroblast growth factor-6 (FGF-6) into denervated medial gastrocnemius muscles improved the function of muscles reinnervated from neurons transplanted into nerve of adult Fischer rats. Factor delivery (10 microg, 4 weeks) began after sciatic nerve transection. After a week of nerve degeneration, 1 million embryonic day 14-15 ventral spinal cord cells were transplanted into the distal tibial stump as a neuron source. Ten weeks later, neurons that expressed motoneuron markers survived in the nerves. More myelinated axons were in nerves to saline-treated muscles than in FGF-6-treated muscles. However, each group showed comparable reductions in muscle fiber atrophy because of reinnervation. Mean reinnervated fiber area was 43%-51% of non-denervated fibers. Denervated fiber area averaged 11%. FGF-6-treated muscles were more fatigable than other reinnervated muscles but had stronger motor units and fewer type I fibers than did saline-treated muscles. FGF-6 thus influenced function by changing the type of fiber reinnervated by transplanted neurons. Deficits in FGF-6 may also contribute to the increase in type I fibers in muscles reinnervated from peripheral axons, suggesting that the effects of FGF-6 on fiber type are independent of the neuron source used for reinnervation.

  4. Relation between α-isoform and phosphatase activity of Na+,K+-ATPase in rat skeletal muscle fiber types.

    PubMed

    Chaillou, M; Rigoard, P; Fares, M; Francois, C; Sottejeau, Y; Maixent, J M

    2011-07-25

    In skeletal muscle the relationship between Na+,K+-ATPase activity and isoform content remains controversial (9,6). It could be due to the fiber-type content, membrane isolation and analytical methods. We investigated the distribution of subunit α1 and α2 Na+,K+-ATPase catalytic isoforms and the Na+,K+-ATPase activity in isolated membranes from white ( type I and glycolitic fibers) and red (type II and oxidative fibers) skeletal muscles. Red Gastrocnemius and White Gastrocnemius muscles were sampled from 8 week-old female Wistar rats and crude membranes were performed. The Na+,K+-ATPase activity and membrane distribution of Na+,K+-ATPase α1 and α2 isoforms were assessed by ouabain sensitive K-phosphatase (Kpase) measurements and Western Blot respectively. The Na+,K+-ATPase activity was 6 fold lower in White Gastrocnemius membranes than in Red Gastrocnemius membranes. The α1 and α2-isoform levels are higher in RG than in White Gastrocnemius. The α1 and α2-subunit Red Gastrocnemius content was significantly higher than in WG. The correlation between crude membrane Kpase activity and both catalytic α-subunit of the Na+,K+-ATPase exist.These data suggest that the Na+,K+-ATPase phosphatase activity correlates with the α1 and α2 isoforms levels in Red Gastrocnemius and White Gastrocnemius and confirms the fiber-specific Na+,K+-ATPase catalytic α-subunits and α2-isoform as the major catalytic isoform in rat skeletal muscle.

  5. Muscle Fiber Type Specific Activation of the Slow Myosin Heavy Chain 2 Promoter by a Non-canonical E-box

    PubMed Central

    Weimer, Kristina; DiMario, Joseph X.

    2016-01-01

    Different mechanisms control skeletal muscle fiber type gene expression at specific times in vertebrate development. Embryonic myogenesis leading to formation of primary muscle fibers in avian species is largely directed by myoblast cell commitment to the formation of diverse fiber types. In contrast, development of different secondary fiber types during fetal myogenesis is partly determined by neural influences. In both primary and secondary chicken muscle fibers, differential expression of the slow myosin heavy chain 2 (MyHC2) gene distinguishes fast from fast/slow muscle fibers. This study focused on the transcriptional regulation of the slow MyHC2 gene in primary myotubes formed from distinct fast/slow and fast myogenic cell lineages. Promoter deletion analyses identified a discrete 86bp promoter segment that conferred fiber type, lineage-specific gene expression in fast/slow versus fast myoblast derived primary myotubes. Sequence analysis and promoter activity assays determined that this segment contains two functional cis-regulatory elements. One element is a non-canonical E-box, and electromobility shift assays demonstrated that both cis-elements interacted with the E-protein, E47. The results indicate that primary muscle fiber type specific expression of the slow MyHC2 gene is controlled by a novel mechanism involving a transcriptional complex that includes E47 at a non-canonical E-box. PMID:26707643

  6. Prolonged C2 spinal hemisection-induced inactivity reduces diaphragm muscle specific force with modest, selective atrophy of type IIx and/or IIb fibers.

    PubMed

    Mantilla, Carlos B; Greising, Sarah M; Zhan, Wen-Zhi; Seven, Yasin B; Sieck, Gary C

    2013-02-01

    The diaphragm muscle (DIAm) is critically responsible for sustaining ventilation. Previously we showed in a commonly used model of spinal cord injury, unilateral spinal cord hemisection at C(2) (SH), that there are minimal changes to muscle fiber cross-sectional area (CSA) and fiber type distribution following 14 days of SH-induced ipsilateral DIAm inactivity. In the present study, effects of long-term SH-induced inactivity on DIAm fiber size and force were examined. We hypothesized that prolonged inactivity would not result in substantial DIAm atrophy or force loss. Adult rats were randomized to control or SH groups (n = 34 total). Chronic bilateral DIAm electromyographic (EMG) activity was monitored during resting breathing. Minimal levels of spontaneous recovery of ipsilateral DIAm EMG activity were evident in 42% of SH rats (<25% of preinjury root mean square amplitude). Following 42 days of SH, DIAm specific force was reduced 39%. There was no difference in CSA for type I or IIa DIAm fibers in SH rats compared with age, weight-matched controls (classification based on myosin heavy chain isoform expression). Type IIx and/or IIb DIAm fibers displayed a modest 20% reduction in CSA (P < 0.05). Overall, there were no differences in the distribution of fiber types or the contribution of each fiber type to the total DIAm CSA. These data indicate that reduced specific force following prolonged inactivity of the DIAm is associated with modest, fiber type selective adaptations in muscle fiber size and fiber type distribution.

  7. The I4895T Mutation in the Type 1 Ryanodine Receptor Induces Fiber-Type Specific Alterations in Skeletal Muscle that Mimic Premature Aging

    PubMed Central

    Boncompagni, Simona; Loy, Ryan E.; Dirksen, Robert T.; Franzini-Armstrong, Clara

    2010-01-01

    SUMMARY The I4898T (IT) mutation in type 1 ryanodine receptor (RyR1), the Ca2+ release channel of the sarcoplasmic reticulum (SR) is linked to a form of central core disease (CCD) in humans and results in a non leaky channel and excitation-contraction uncoupling. We characterized age- and fiber type-dependent alterations in muscle ultrastructure, as well as the magnitude and spatiotemporal properties of evoked Ca2+ release in heterozygous Ryr1I4895T/WT (IT/+) knock-in mice on a mixed genetic background. The results indicate a classical but mild CCD phenotype that includes muscle weakness and the presence of mitochondrial-deficient areas in type I fibers. Electrically-evoked Ca2+ release is significantly reduced in single FDB fibers from young and old IT/+ mice. Structural changes are strongly fiber type-specific, affecting type I and IIB/IIX fibers in very distinct ways, and sparing type IIA fibers. Ultrastructural alterations in our IT/+ mice are also present in wild type, but at a lower frequency and older ages, suggesting that the disease mutation on the mixed background promotes an acceleration of normal age-dependent changes. The observed functional and structural alterations and their similarity to age-associated changes are entirely consistent with the known properties of the mutated channel, which result in reduced calcium release as is also observed in normal aging muscle. In strong contrast to these observations, a subset of patients with the analogous human heterozygous mutation and IT/+ mice on an inbred 129S2/SvPasCrl background exhibit a more severe disease phenotype, which is not directly consistent with the mutated channel properties. PMID:20961389

  8. In vivo Ca2+ buffering capacity and microvascular oxygen pressures following muscle contractions in diabetic rat skeletal muscles: fiber-type specific effects.

    PubMed

    Eshima, Hiroaki; Poole, David C; Kano, Yutaka

    2015-07-15

    In Type 1 diabetes, skeletal muscle resting intracellular Ca(2+) concentration ([Ca(2+)]i) homeostasis is impaired following muscle contractions. It is unclear to what degree this behavior is contingent upon fiber type and muscle oxygenation conditions. We tested the hypotheses that: 1) the rise in resting [Ca(2+)]i evident in diabetic rat slow-twitch (type I) muscle would be exacerbated in fast-twitch (type II) muscle following contraction; and 2) these elevated [Ca(2+)]i levels would relate to derangement of microvascular partial pressure of oxygen (PmvO2 ) rather than sarcoplasmic reticulum dysfunction per se. Adult male Wistar rats were divided randomly into diabetic (DIA: streptozotocin ip) and healthy (CONT) groups. Four weeks later extensor digitorum longus (EDL, predominately type II fibers) and soleus (SOL, predominately type I fibers) muscle contractions were elicited by continuous electrical stimulation (120 s, 100 Hz). Ca(2+) imaging was achieved using fura 2-AM in vivo (i.e., circulation intact). DIA increased fatigability in EDL (P < 0.05) but not SOL. In recovery, SOL [Ca(2+)]i either returned to its resting baseline within 150 s (CONT 1.00 ± 0.02 at 600 s) or was not elevated in recovery at all (DIA 1.03 ± 0.02 at 600 s, P > 0.05). In recovery, EDL CONT [Ca(2+)]i also decreased to values not different from baseline (1.06 ± 0.01, P > 0.05) at 600 s. In marked contrast, EDL DIA [Ca(2+)]i remained elevated for the entire recovery period (i.e., 1.23 ± 0.03 at 600 s, P < 0.05). The inability of [Ca(2+)]i to return to baseline in EDL DIA was not associated with any reduction of SR Ca(2+)-ATPase (SERCA) 1 or SERCA2 protein levels (both increased 30-40%, P < 0.05). However, Pmv(O2) recovery kinetics were markedly slowed in EDL such that mean Pmv(O2) was substantially depressed (CONT 27.9 ± 2.0 vs. DIA 18.4 ± 2.0 Torr, P < 0.05), and this behavior was associated with the elevated [Ca(2+)]i. In contrast, this was not the case for SOL (P > 0.05) in that

  9. Acute effects of taurine on sarcoplasmic reticulum Ca2+ accumulation and contractility in human type I and type II skeletal muscle fibers.

    PubMed

    Dutka, T L; Lamboley, C R; Murphy, R M; Lamb, G D

    2014-10-01

    Taurine occurs in high concentrations in muscle and is implicated in numerous physiological processes, yet its effects on many aspects of contractility remain unclear. Using mechanically skinned segments of human vastus lateralis muscle fibers, we characterized the effects of taurine on sarcoplasmic reticulum (SR) Ca2+ accumulation and contractile apparatus properties in type I and type II fibers. Prolonged myoplasmic exposure (>10 min) to taurine substantially increased the rate of accumulation of Ca2+ by the SR in both fiber types, with no change in the maximum amount accumulated; no such effect was found with carnosine. SR Ca2+ accumulation was similar with 10 or 20 mM taurine, but was significantly slower at 5 mM taurine. Cytoplasmic taurine (20 mM) had no detectable effects on the responsiveness of the Ca2+ release channels in either fiber type. Taurine caused a small increase in Ca2+ sensitivity of the contractile apparatus in type I fibers, but type II fibers were unaffected; maximum Ca(2+)-activated force was unchanged in both cases. The effects of taurine on SR Ca2+ accumulation (1) only became apparent after prolonged cytoplasmic exposure, and (2) persisted for some minutes after complete removal of taurine from the cytoplasm, consistent with the hypothesis that the effects were due to an action of taurine from inside the SR. In summary, taurine potentiates the rate of SR Ca2+ uptake in both type I and type II human fibers, possibly via an action from within the SR lumen, with the degree of potentiation being significantly reduced at low physiological taurine levels.

  10. Comparison of mean frequency and median frequency in evaluating muscle fiber type selection in varying gait speed across healthy young adult individuals.

    PubMed

    Chan, C K; Timothy, G Fu; Yeow, C H

    2016-08-01

    The preferential slow and fast twitches fiber involvement in varying gait speed has not been thoroughly investigated. Attempt to classify fiber type in changing speed should be closely investigated and scrutinized as the histochemical-related experiments are cumbersome and time consuming. In addressing this issue, electromyography (EMG) is utilized to extract the muscle fiber type features by altering the muscle fatigue indices, namely mean frequency (MNF) and median frequency (MDF). Recently, there are no universal indices to determine the muscle type. In this paper, the MNF and MDF are employed in discovering the muscle type variation as the speed changes. Besides drawing the potential of MNF and MDF in unveiling the muscle type, both the parameters are applied to investigate the muscles that are recruited and which muscle type are involved as the gait velocity changes. In this study, six healthy and young participants are recruited, whereby the EMG sensors are placed on twelve lower extremity muscles. The EMG signals are then processed via Matlab software to deduce MNF and MDF. The MNF and MDF are determined from every of the phase gait, namely stance and swing. From the results obtained, it reveals that the superiority of the MNF over the MDF in determining and interpreting the muscle recruitment in both gait phases as the speed increases. The MNF, moreover, is able to show an apparent difference in muscle type selection compared to MDF. Interestingly, it is discovered that as the speed increases from slow to fast, the MNF decreases, which indicates that more muscle fiber type I is recruited. Contrarily, the MNF increases as the speed intensity decreases, which indicates that the distribution of muscle type II is prominent.

  11. Eccentric contraction-induced injury to type I, IIa, and IIa/IIx muscle fibers of elderly adults

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Muscles of old laboratory rodents experience exaggerated force losses after eccentric contractile activity. We extended this line of inquiry to humans and investigated the influence of fiber myosin heavy chain (MHC) isoform content on the injury process. Skinned muscle fiber segments, prepared from ...

  12. Age-related changes in rat intrinsic laryngeal muscles: analysis of muscle fibers, muscle fiber proteins, and subneural apparatuses.

    PubMed

    Nishida, Naoya; Taguchi, Aki; Motoyoshi, Kazumi; Hyodo, Masamitsu; Gyo, Kiyofumi; Desaki, Junzo

    2013-03-01

    We compared age-related changes in the intrinsic laryngeal muscles of aged and young adult rats by determining the number and diameter of muscle fibers, contractile muscle protein (myosin heavy chain isoforms, MHC) composition, and the morphology of the subneural apparatuses. In aged rats, both the numbers and the diameters of muscle fibers decreased in the cricothyroid (CT) muscle. The number of fibers, but not diameter, decreased in the thyroarytenoid (TA) muscle. In the posterior cricoarytenoid (PCA) muscle, neither the number nor the diameter of fibers changed significantly. Aging was associated with a decrease in type IIB and an increase in type IIA MHC isoform levels in CT muscle, but no such changes were observed in the TA or PCA muscles. Morphological examination of primary synaptic clefts of the subneural apparatus revealed that aging resulted in decreased labyrinthine and increased depression types in only the CT muscle. In the aged group, morphologically immature subneural apparatuses were found infrequently in the CT muscle, indicating continued tissue remodeling. We suggest, therefore, that age-related changes in the intrinsic laryngeal muscles primarily involve the CT muscle, whereas the structures of the TA and PCA muscles may better resist aging processes and therefore are less vulnerable to functional impairment. This may reflect differences in their roles; the CT muscle controls the tone of the vocal folds, while the TA and PCA muscles play an essential role in vital activities such as respiration and swallowing.

  13. Hydrostatic compression in glycerinated rabbit muscle fibers.

    PubMed

    Ranatunga, K W; Fortune, N S; Geeves, M A

    1990-12-01

    Glycerinated muscle fibers isolated from rabbit psoas muscle, and a number of other nonmuscle elastic fibers including glass, rubber, and collagen, were exposed to hydrostatic pressures of up to 10 MPa (100 Atm) to determine the pressure sensitivity of their isometric tension. The isometric tension of muscle fibers in the relaxed state (passive tension) was insensitive to increased pressure, whereas the muscle fiber tension in rigor state increased linearly with pressure. The tension of all other fiber types (except rubber) also increased with pressure; the rubber tension was pressure insensitive. The pressure sensitivity of rigor tension was 2.3 kN/m2/MPa and, in comparison with force/extension relation determined at atmospheric pressure, the hydrostatic compression in rigor muscle fibers was estimated to be 0.03% Lo/MPa. As reported previously, the active muscle fiber tension is depressed by increased pressure. The possible underlying basis of the different pressure-dependent tension behavior in relaxed, rigor, and active muscle is discussed.

  14. Intramyocellular lipid dependence on skeletal muscle fiber type and orientation characterized by diffusion tensor imaging and 1H-MRS

    NASA Astrophysics Data System (ADS)

    Valaparla, Sunil K.; Gao, Feng; Abdul-Ghani, Muhammad; Clarke, Geoffrey D.

    2014-03-01

    When muscle fibers are aligned with the B0 field, intramyocellular lipids (IMCL), important for providing energy during physical activity, can be resolved in proton magnetic resonance spectra (1H-MRS). Various muscles of the leg differ significantly in their proportion of fibers and angular distribution. This study determined the influence of muscle fiber type and orientation on IMCL using 1H-MRS and diffusion tensor imaging (DTI). Muscle fiber orientation relative to B0 was estimated by pennation angle (PA) measurements from DTI, providing orientation-specific extramyocellular lipid (EMCL) chemical shift data that were used for subject-specific IMCL quantification. Vastus lateralis (VL), tibialis anterior (TA) and soleus (SO) muscles of 6 healthy subjects (21-40 yrs) were studied on a Siemens 3T MRI system with a flex 4-channel coil. 1H-MRS were acquired using stimulated echo acquisition mode (STEAM, TR=3s, TE=270ms). DTI was performed using single shot EPI (b=600s/mm2, 30 directions, TR=4.5s, TE=82ms, and ten×5mm slices) with center slice indexed to the MRS voxel. The average PA's measured from ROI analysis of primary eigenvectors were PA=19.46+/-5.43 for unipennate VL, 15.65+/-3.73 for multipennate SO, and 7.04+/-3.34 for bipennate TA. Chemical shift (CS) was calculated using [3cos2θ-1] dependence: 0.17+/-0.02 for VL, 0.18+/-0.01 for SO and 0.19+/-0.004 ppm for TA. IMCL-CH2 concentrations from spectral analysis were 12.77+/-6.3 for VL, 3.07+/-1.63 for SO and 0.27+/-0.08 mmol/kg ww for TA. Small PA's were measured in TA and large CS with clear separation between EMCL and IMCL peaks were observed. Larger variations in PA were measured VL and SO resulting in an increased overlap of the EMCL on IMCL peaks.

  15. Bovine sire selection based on maintenance energy affects muscle fiber type and meat color of F1 progeny.

    PubMed

    Thornton, K J; Welch, C M; Davis, L C; Doumit, M E; Hill, R A; Murdoch, G K

    2012-05-01

    proportion of type IIa fibers (r = -0.42 and P = 0.03) in the steers. This indicates that relative mRNA expression of glyc may serve as a marker of muscle glycogen storage capacity in steers. Thus, selection for efficient Red Angus beef cattle based on sire ME(M) EPD does not adversely affect meat quality in F(1) progeny, based on the variables assessed in this study. Furthermore, selection for progeny from low-ME(M) EPD sires may improve fresh meat quality within Red Angus beef cattle.

  16. Carbonic Anhydrase III Is Expressed in Mouse Skeletal Muscles Independent of Fiber Type-Specific Myofilament Protein Isoforms and Plays a Role in Fatigue Resistance

    PubMed Central

    Feng, Han-Zhong; Jin, J.-P.

    2016-01-01

    Carbonic anhydrase III (CAIII) is a metabolic enzyme and a regulator for intracellular pH. CAIII has been reported with high level expression in slow twitch skeletal muscles. Here we demonstrate that CAIII is expressed in multiple slow and fast twitch muscles of adult mouse independent of the expression of myosin isoforms. Expressing similar fast type of myofilament proteins, CAIII-positive tibial anterior (TA) muscle exhibits higher tolerance to fatigue than that of CAIII-negative fast twitch extensor digitorum longus (EDL) muscle in in situ contractility studies. We further studied the muscles of CAIII knockout (Car3-KO) mice. The loss of CAIII in soleus and TA muscles in Car3-KO mice did not change muscle mass, sarcomere protein isoform contents, and the baseline twitch and tetanic contractility as compared with age-matched wild type (WT) controls. On the other hand, Car3-KO TA muscle showed faster force reduction at the beginning but higher resistance at the end during a fatigue test, followed by slower post fatigue recovery than that of WT TA muscle. Superfused Car3-KO soleus muscle also had faster total force reduction during fatigue test than that of WT soleus. However, it showed a less elevation of resting tension followed by a better post fatigue recovery under acidotic stress. CAIII was detected in neonatal TA and EDL muscle, downregulated during development, and then re-expressed in adult TA but not EDL muscles. The expression of CAIII in Tnnt1-KO myopathy mouse soleus muscle that has diminished slow fiber contents due to the loss of slow troponin T remained high. Car3-KO EDL, TA, and soleus muscles showed no change in the expression of mitochondria biomarker proteins. The data suggest a fiber type independent expression of CAIII with a role in the regulation of intracellular pH in skeletal muscle and may be explored as a target for improving fatigue resistance and for the treatment of TNNT1 myopathies. PMID:28018233

  17. Carbonic Anhydrase III Is Expressed in Mouse Skeletal Muscles Independent of Fiber Type-Specific Myofilament Protein Isoforms and Plays a Role in Fatigue Resistance.

    PubMed

    Feng, Han-Zhong; Jin, J-P

    2016-01-01

    Carbonic anhydrase III (CAIII) is a metabolic enzyme and a regulator for intracellular pH. CAIII has been reported with high level expression in slow twitch skeletal muscles. Here we demonstrate that CAIII is expressed in multiple slow and fast twitch muscles of adult mouse independent of the expression of myosin isoforms. Expressing similar fast type of myofilament proteins, CAIII-positive tibial anterior (TA) muscle exhibits higher tolerance to fatigue than that of CAIII-negative fast twitch extensor digitorum longus (EDL) muscle in in situ contractility studies. We further studied the muscles of CAIII knockout (Car3-KO) mice. The loss of CAIII in soleus and TA muscles in Car3-KO mice did not change muscle mass, sarcomere protein isoform contents, and the baseline twitch and tetanic contractility as compared with age-matched wild type (WT) controls. On the other hand, Car3-KO TA muscle showed faster force reduction at the beginning but higher resistance at the end during a fatigue test, followed by slower post fatigue recovery than that of WT TA muscle. Superfused Car3-KO soleus muscle also had faster total force reduction during fatigue test than that of WT soleus. However, it showed a less elevation of resting tension followed by a better post fatigue recovery under acidotic stress. CAIII was detected in neonatal TA and EDL muscle, downregulated during development, and then re-expressed in adult TA but not EDL muscles. The expression of CAIII in Tnnt1-KO myopathy mouse soleus muscle that has diminished slow fiber contents due to the loss of slow troponin T remained high. Car3-KO EDL, TA, and soleus muscles showed no change in the expression of mitochondria biomarker proteins. The data suggest a fiber type independent expression of CAIII with a role in the regulation of intracellular pH in skeletal muscle and may be explored as a target for improving fatigue resistance and for the treatment of TNNT1 myopathies.

  18. The effect of fiber-type heterogeneity on optimized work and power output of hindlimb muscles of the salamander Ambystoma tigrinum.

    PubMed

    Ashley-Ross, M A; Barker, J U

    2002-09-01

    Most vertebrate muscles are composed of a mixture of fiber types. However, studies of muscle mechanics have concentrated on homogeneous bundles of fibers. Hindlimb muscles of the tiger salamander, Ambystoma tigrinum, present an excellent system to explore the consequences of fiber heterogeneity. Isometric twitches and work loops were obtained in vitro from two muscles, the m. iliotibialis pars posterior (heterogeneous, containing types I, IIa and IIb fibers) and the m. iliofibularis (nearly homogeneous for type IIa fibers). Maximal isometric twitch and tetanic stresses in m. iliotibialis posterior were significantly greater than in iliofibularis. Work loops were obtained over a range of frequencies (0.5-3.0 Hz) and strains (2-6% muscle length) that encompassed the observed ranges in vivo. Work per cycle from the homogeneous iliofibularis declined from 1.5-3.0 Hz, while that from the heterogeneous m. iliotibialis posterior increased from 0.5 Hz to 2.5 Hz and declined at 3.0 Hz. Power output from the iliofibularis rose with frequency to at least 3 Hz; power from the iliotibialis posterior rose with frequency to 2.5 Hz and declined thereafter. Mass-specific work per cycle and power output were higher in iliofibularis than iliotibialis posterior over most frequencies and strains tested.

  19. [Morphological and physiological characterization of fiber types in the iliofibular muscle of Rana esculenta].

    PubMed

    Dauber, W

    1977-01-01

    In both longitudinal and cross sections of the M. iliofibularis of Rana esculenta three types of muscle fibres are identified by means of light and electron microscopy. These fibretypes called A-, B- and C-fibres are according to the fibres of m. rectus abdominis of the frog. They can be compared with the fibres of the m. rectus abdominis of rat and mouse. But there is another distribution of the fibretypes A, B and C in the m. iliofibularis and in the m. rectus abdominis. The m. iliofibularis is divided into two parts called "Tonusbündel" and "nichttonischer Teil" by means of their reaction to acetylcholine. The surface of the "Tonusbündel" consists of A-, B- and C-fibres while its inside is onlyformed by A- and B-fibres. They continue the "Tonusbündel" in the "nichttonischer Teil". This part chiefly consists of A-fibres. In cross sections their myofibrils are larger in their extent than the A-fibres known before. Therefore the A-fibretype has to be distinguished into two A-fibres: A1 and A2. The new one is called A2-fibre. A1-fibre is described in the "Tonusbündel" and in further investigations. The difference between the two fibres can be understood as a greater manifestation of power of the A1-fibre. The surface of the "nichttonischer Teil" of the m. iliofibularis consists of A2-fibres which easily could be found opposite the "Tonusbündel". At this point in contrary to the "Tonusbündel" could be found a defined morphological substrate for physiological investigations. The different reactions of "Tonusbündel" and "nichttonischer Teil" to acetylcholine could only be explained by the sum of reactions of all fibretypes in each bundle in correspondence with the reaction of the fibres in the neighbour bundle. But their different behaviour by summer- and winterfrogs is unknown. Therefore it is to discuss whether it is allowed to refer generally the results to "muscle" or "musclefibre" got from frogs living in cooled rooms. It is known in literature that not all

  20. Impact of maximal strength training on work efficiency and muscle fiber type in the elderly: Implications for physical function and fall prevention.

    PubMed

    Wang, Eivind; Nyberg, Stian Kwak; Hoff, Jan; Zhao, Jia; Leivseth, Gunnar; Tørhaug, Tom; Husby, Otto Schnell; Helgerud, Jan; Richardson, Russell S

    2017-02-21

    Although aging is typically associated with a decreased efficiency of locomotion, somewhat surprisingly, there is also a reduction in the proportion of less efficient fast-twitch Type II skeletal muscle fibers and subsequently a greater propensity for falls. Maximal strength training (MST), with an emphasis on velocity in the concentric phase, improves maximal strength, the rate of force development (RFD), and work efficiency, but the impact on muscle morphology in the elderly is unknown. Therefore we evaluated force production, walking work efficiency, and muscle morphology in 11 old (72±3years) subjects before and after MST of the legs. Additionally, for reference, the MST-induced morphometric changes were compared with 7 old (74±6years) subjects who performed conventional strength training (CST), with focus on hypertrophy, as well as 13 young (24±2years) controls. As expected, MST in the old improved maximal strength (68%), RFD (48%), and work efficiency (12%), restoring each to a level similar to the young. However, of importance, these MST-induced functional changes were accompanied by a significant increase in the size (66%) and shift toward a larger percentage (56%) of Type II skeletal muscle fibers, mirroring the adaptations in the hypertrophy trained old subjects, with muscle composition now being similar to the young. In conclusion, MST can increase both work efficiency and Type II skeletal muscle fiber size and percentage in the elderly, supporting the potential role of MST as a countermeasure to maintain both physical function and fall prevention in this population.

  1. Muscles Susceptibility to Ischemia-Reperfusion Injuries Depends on Fiber Type Specific Antioxidant Level.

    PubMed

    Charles, Anne-Laure; Guilbert, Anne-Sophie; Guillot, Max; Talha, Samy; Lejay, Anne; Meyer, Alain; Kindo, Michel; Wolff, Valérie; Bouitbir, Jamal; Zoll, Joffrey; Geny, Bernard

    2017-01-01

    Muscle injury resulting from ischemia-reperfusion largely aggravates patient prognosis but whether and how muscle phenotype modulates ischemia-reperfusion-induced mitochondrial dysfunction remains to be investigated. We challenged the hypothesis that glycolytic muscles are more prone to ischemia-reperfusion-induced injury than oxidative skeletal muscles. We therefore determined simultaneously the effect of 3 h of ischemia induced by aortic clamping followed by 2 h of reperfusion (IR, n = 11) on both gastrocnemius and soleus muscles, as compared to control animals (C, n = 11). Further, we investigated whether tempol, an antioxidant mimicking superoxide dismutase, might compensate a reduced defense system, likely characterizing glycolytic muscles (IR-Tempol, n = 7). In the glycolytic gastrocnemius muscle, as compared to control, ischemia-reperfusion significantly decreased mitochondrial respiration (-30.28 ± 6.16%, p = 0.003), increased reactive oxygen species production (+79.15 ± 28.72%, p = 0.04), and decreased reduced glutathione (-28.19 ± 6.80%, p = 0.011). Less deleterious effects were observed in the oxidative soleus muscle (-6.44 ± 6.30%, +4.32 ± 16.84%, and -8.07 ± 10.84%, respectively), characterized by enhanced antioxidant defenses (0.63 ± 0.05 in gastrocnemius vs. 1.24 ± 0.08 μmol L(-1) g(-1) in soleus). Further, when previously treated with tempol, glycolytic muscle was largely protected against the deleterious effects of ischemia-reperfusion. Thus, oxidative skeletal muscles are more protected than glycolytic ones against ischemia-reperfusion, thanks to their antioxidant pool. Such pivotal data support that susceptibility to ischemia-reperfusion-induced injury differs between organs, depending on their metabolic phenotypes. This suggests a need to adapt therapeutic strategies to the specific antioxidant power of the target organ to be protected.

  2. Muscles Susceptibility to Ischemia-Reperfusion Injuries Depends on Fiber Type Specific Antioxidant Level

    PubMed Central

    Charles, Anne-Laure; Guilbert, Anne-Sophie; Guillot, Max; Talha, Samy; Lejay, Anne; Meyer, Alain; Kindo, Michel; Wolff, Valérie; Bouitbir, Jamal; Zoll, Joffrey; Geny, Bernard

    2017-01-01

    Muscle injury resulting from ischemia-reperfusion largely aggravates patient prognosis but whether and how muscle phenotype modulates ischemia-reperfusion-induced mitochondrial dysfunction remains to be investigated. We challenged the hypothesis that glycolytic muscles are more prone to ischemia-reperfusion-induced injury than oxidative skeletal muscles. We therefore determined simultaneously the effect of 3 h of ischemia induced by aortic clamping followed by 2 h of reperfusion (IR, n = 11) on both gastrocnemius and soleus muscles, as compared to control animals (C, n = 11). Further, we investigated whether tempol, an antioxidant mimicking superoxide dismutase, might compensate a reduced defense system, likely characterizing glycolytic muscles (IR-Tempol, n = 7). In the glycolytic gastrocnemius muscle, as compared to control, ischemia-reperfusion significantly decreased mitochondrial respiration (−30.28 ± 6.16%, p = 0.003), increased reactive oxygen species production (+79.15 ± 28.72%, p = 0.04), and decreased reduced glutathione (−28.19 ± 6.80%, p = 0.011). Less deleterious effects were observed in the oxidative soleus muscle (−6.44 ± 6.30%, +4.32 ± 16.84%, and −8.07 ± 10.84%, respectively), characterized by enhanced antioxidant defenses (0.63 ± 0.05 in gastrocnemius vs. 1.24 ± 0.08 μmol L−1 g−1 in soleus). Further, when previously treated with tempol, glycolytic muscle was largely protected against the deleterious effects of ischemia-reperfusion. Thus, oxidative skeletal muscles are more protected than glycolytic ones against ischemia-reperfusion, thanks to their antioxidant pool. Such pivotal data support that susceptibility to ischemia-reperfusion-induced injury differs between organs, depending on their metabolic phenotypes. This suggests a need to adapt therapeutic strategies to the specific antioxidant power of the target organ to be protected. PMID:28220081

  3. Downhill Running Excessive Training Inhibits Hypertrophy in Mice Skeletal Muscles with Different Fiber Type Composition.

    PubMed

    da Rocha, Alisson L; Pereira, Bruno C; Pauli, José R; de Souza, Claudio T; Teixeira, Giovana R; Lira, Fábio S; Cintra, Dennys E; Ropelle, Eduardo R; Júnior, Carlos R B; da Silva, Adelino S R

    2016-05-01

    The aim of this study was to verify the effects of running overtraining protocols performed in downhill, uphill, and without inclination on the proteins related to hypertrophy signaling pathway in extensor digitorum longus (EDL) and soleus of C57BL/6 mice. We also performed histological and stereological analyses. Rodents were divided into control (CT; sedentary mice), overtrained by downhill running (OTR/down), overtrained by uphill running (OTR/up), and overtrained by running without inclination (OTR). The incremental load, exhaustive, and grip force tests were used as performance evaluation parameters. 36 h after the grip force test, EDL and soleus were removed and immediately used for immunoblotting analysis or stored at -80°C for histological and stereological analyses. For EDL, OTR/down decreased the protein kinase B (Akt) and tuberous sclerosis protein 2 (TSC2) phosphorylation (p), and increased myostatin, receptor-activated Smads (pSMAD2-3), and insulin receptor substrate-1 (pIRS-1; Ser307/636). OTR/down also presented low and high relative proportions of cytoplasm and connective tissue, respectively. OTR/up increased the mammalian target of rapamycin (pmTOR), 70-kDa ribosomal protein S6 kinase 1 (pS6K1) and pSMAD2-3, and decreased pTSC2. OTR decreased pTSC2 and increased pIRS-1 (Ser636). For soleus, OTR/down increased S6 ribosomal protein (pS6RP) and pSMAD2-3, and decreased pIRS-1 (Ser639). OTR/up decreased pS6K1, pS6RP and pIRS-1 (Ser639), and increased pTSC2 (Ser939), and pSMAD2-3. OTR increased pS6RP, 4E-binding protein-1 (p4E-BP1), pTSC2 (Ser939), and pSMAD2-3, and decreased pIRS-1 (Ser639). In summary, OTR/down inhibited the skeletal muscle hypertrophy with concomitant signs of atrophy in EDL. The effects of OTR/up and OTR depended on the analyzed skeletal muscle type.

  4. Fiber Type Conversion by PGC-1α Activates Lysosomal and Autophagosomal Biogenesis in Both Unaffected and Pompe Skeletal Muscle

    PubMed Central

    Takikita, Shoichi; Schreiner, Cynthia; Baum, Rebecca; Xie, Tao; Ralston, Evelyn; Plotz, Paul H.; Raben, Nina

    2010-01-01

    PGC-1α is a transcriptional co-activator that plays a central role in the regulation of energy metabolism. Our interest in this protein was driven by its ability to promote muscle remodeling. Conversion from fast glycolytic to slow oxidative fibers seemed a promising therapeutic approach in Pompe disease, a severe myopathy caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA) which is responsible for the degradation of glycogen. The recently approved enzyme replacement therapy (ERT) has only a partial effect in skeletal muscle. In our Pompe mouse model (KO), the poor muscle response is seen in fast but not in slow muscle and is associated with massive accumulation of autophagic debris and ineffective autophagy. In an attempt to turn the therapy-resistant fibers into fibers amenable to therapy, we made transgenic KO mice expressing PGC-1α in muscle (tgKO). The successful switch from fast to slow fibers prevented the formation of autophagic buildup in the converted fibers, but PGC-1α failed to improve the clearance of glycogen by ERT. This outcome is likely explained by an unexpected dramatic increase in muscle glycogen load to levels much closer to those observed in patients, in particular infants, with the disease. We have also found a remarkable rise in the number of lysosomes and autophagosomes in the tgKO compared to the KO. These data point to the role of PGC-1α in muscle glucose metabolism and its possible role as a master regulator for organelle biogenesis - not only for mitochondria but also for lysosomes and autophagosomes. These findings may have implications for therapy of lysosomal diseases and other disorders with altered autophagy. PMID:21179212

  5. Endurance training induces fiber type-specific revascularization in hindlimb skeletal muscles of rats with chronic heart failure

    PubMed Central

    Ranjbar, Kamal; Ardakanizade, Malihe; Nazem, Farzad

    2017-01-01

    Objective(s): Previous studies showed that skeletal muscle microcirculation was reduced in chronic heart failure. The aim of this study was to investigate the effects of endurance training on capillary and arteriolar density of fast and slow twitch muscles in rats with chronic heart failure. Materials and Methods: Four weeks after surgeries (left anterior descending (LAD) artery occlusion), chronic heart failure rats were divided into 3 groups: Sham (Sham, n=10); Sedentary (Sed, n=10); Exercise training (Ex, n=10). Ex group rats were subjected to endurance training in the form of treadmill running with moderate intensity for 10 weeks. Results: Exercise training significantly increased capillary density and capillary to fiber ratio (P<0.05) in slow twitch muscle, but didn’t change fast twitch muscle capillary density and capillary to fiber ratio. Furthermore, arteriolar density in fast twitch muscle increased remarkably (P<0.05) in response to training, but slow twitch muscle arteriolar density did not change in response to exercise in chronic heart failure rats. HIF-1 increased (P<0.01) but VEGF and FGF-2 mRNA did not change in slow twitch muscle after training. In fast twitch muscle, HIF-1 mRNA increased (P<0.05), and VEGF and angiostatin decreased (P<0.01) significantly after training. Conclusion: Endurance training ameliorates fast and slow twitch muscle revascularization non-uniformly in chronic heart failure rats by increasing capillary density in slow twitch muscle and arteriolar density in fast twitch muscle. The difference in revascularization at slow and fast twitch muscles may be induced by the difference in angiogenic and angiostatic gene expression response to endurance training. PMID:28133530

  6. Acyl-CoA binding protein expression is fiber type- specific and elevated in muscles from the obese insulin-resistant Zucker rat.

    PubMed

    Franch, Jesper; Knudsen, Jens; Ellis, Bronwyn A; Pedersen, Preben K; Cooney, Gregory J; Jensen, Jørgen

    2002-02-01

    Accumulation of acyl-CoA is hypothesized to be involved in development of insulin resistance. Acyl-CoA binds to acyl-CoA binding protein (ACBP) with high affinity, and therefore knowledge about ACBP concentration is important for interpreting acyl-CoA data. In the present study, we used a sandwich enzyme-linked immunosorbent assay to quantify ACBP concentration in different muscle fiber types. Furthermore, ACBP concentration was compared in muscles from lean and obese Zucker rats. Expression of ACBP was highest in the slow-twitch oxidative soleus muscle and lowest in the fast-twitch glycolytic white gastrocnemius (0.46 +/- 0.02 and 0.16 +/- 0.005 microg/mg protein, respectively). Expression of ACBP was soleus > red gastrocnemius > extensor digitorum longus > white gastrocnemius. Similar fiber type differences were found for carnitine palmitoyl transferase (CPT)-1, and a correlation was observed between ACBP and CPT-1. Muscles from obese Zucker rats had twice the triglyceride content, had approximately twice the long-chain acyl CoA content, and were severely insulin resistant. ACBP concentration was approximately 30% higher in all muscles from obese rats. Activities of CPT-1 and 3-hydroxy-acyl-CoA dehydrogenase were increased in muscles from obese rats, whereas citrate synthase activity was similar. In conclusion, ACBP expression is fiber type-specific with the highest concentration in oxidative muscles and the lowest in glycolytic muscles. The 90% increase in the concentration of acyl-CoA in obese Zucker muscle compared with only a 30% increase in the concentration of ACBP supports the hypothesis that an increased concentration of free acyl-CoA is involved in the development of insulin resistance.

  7. Experiment K-6-21. Effect of microgravity on 1) metabolic enzymes of type 1 and type 2 muscle fibers and on 2) metabolic enzymes, neutransmitter amino acids, and neurotransmitter associated enzymes in motor and somatosensory cerebral cortex. Part 1: Metabolic enzymes of individual muscle fibers; part 2: metabolic enzymes of hippocampus and spinal cord

    NASA Technical Reports Server (NTRS)

    Lowry, O.; Mcdougal, D., Jr.; Nemeth, Patti M.; Maggie, M.-Y. Chi; Pusateri, M.; Carter, J.; Manchester, J.; Norris, Beverly; Krasnov, I.

    1990-01-01

    The individual fibers of any individual muscle vary greatly in enzyme composition, a fact which is obscured when enzyme levels of a whole muscle are measured. The purpose of this study was therefore to assess the changes due to weightless on the enzyme patterns composed by the individual fibers within the flight muscles. In spite of the limitation in numbers of muscles examined, it is apparent that: (1) that the size of individual fibers (i.e., their dry weight) was reduced about a third, (2) that this loss in dry mass was accompanied by changes in the eight enzymes studied, and (3) that these changes were different for the two muscles, and different for the two enzyme groups. In the soleus muscle the absolute amounts of the three enzymes of oxidative metabolism decreased about in proportion to the dry weight loss, so that their concentration in the atrophic fibers was almost unchanged. In contrast, there was little loss among the four enzymes of glycogenolysis - glycolysis so that their concentrations were substantially increased in the atrophic fibers. In the TA muscle, these seven enzymes were affected in just the opposite direction. There appeared to be no absolute loss among the oxidative enzymes, whereas the glycogenolytic enzymes were reduced by nearly half, so that the concentrations of the first metabolic group were increased within the atrophic fibers and the concentrations of the second group were only marginally decreased. The behavior of hexokinase was exceptional in that it did not decrease in absolute terms in either type of muscle and probably increased as much as 50 percent in soleus. Thus, their was a large increase in concentration of this enzyme in the atrophied fibers of both muscles. Another clear-cut finding was the large increase in the range of activities of the glycolytic enzymes among individual fibers of TA muscles. This was due to the emergence of TA fibers with activities for enzymes of this group extending down to levels as low as

  8. Haplotype diversity in the equine myostatin gene with focus on variants associated with race distance propensity and muscle fiber type proportions.

    PubMed

    Petersen, Jessica L; Valberg, Stephanie J; Mickelson, James R; McCue, Molly E

    2014-12-01

    Two variants in the equine myostatin gene (MSTN), including a T/C SNP in the first intron and a 227-bp SINE insertion in the promoter, are associated with muscle fiber type proportions in the Quarter Horse (QH) and with the prediction of race distance propensity in the Thoroughbred (TB). Genotypes from these loci, along with 18 additional variants surrounding MSTN, were examined in 301 horses of 14 breeds to evaluate haplotype relationships and diversity. The C allele of intron 1 was found in 12 of 14 breeds at a frequency of 0.27; the SINE was observed in five breeds, but common in only the TB and QH (0.73 and 0.48 respectively). Haplotype data suggest the SINE insertion is contemporary to and arose upon a haplotype containing the intron 1 C allele. Gluteal muscle biopsies of TBs showed a significant association of the intron 1 C allele and SINE with a higher proportion of Type 2B and lower proportion of Type 1 fibers. However, in the Belgian horse, in which the SINE is not present, the intron 1 SNP was not associated with fiber type proportions, and evaluation of fiber type proportions across the Belgian, TB and QH breeds shows the significant effect of breed on fiber type proportions is negated when evaluating horses without the SINE variant. These data suggest the SINE, rather than the intron 1 SNP, is driving the observed muscle fiber type characteristics and is the variant targeted by selection for short-distance racing.

  9. Effect of acute and chronic eccentric exercise on FOXO1 mRNA expression as fiber type transition factor in rat skeletal muscles.

    PubMed

    Azad, Milad; Khaledi, Neda; Hedayati, Mehdi

    2016-06-15

    Skeletal muscle is a highly elastic tissue which can respond to various functional demands by altering fiber-type composition. Exercise affects muscle fiber phenotype. One of the transcription factors that induce fiber-type transition is forkhead box O1 (FOXO1). Since eccentric contraction considered an essential part of exercise, so we are interested to see the effects of eccentric exercise (acute/chronic) on FOXO1 as an important factor of fiber-type transition in rat skeletal muscles. Twenty-four Sprague-Dawley rats (190-235g) were divided to 3 groups of 8 rats: 1) chronic eccentric exercise (CEE), 2) acute eccentric exercise (AEE), and 3) control (C). The exercise groups underwent downhill running protocol. CEE was running on treadmill in 3 days of week for 9 weeks, that slope and duration gradually managed from -4° to -16° and 15 to 90 min, respectively. AEE group was running with 16 m/min on -16° slope for 3 consecutive days that included 18 sets of 5 min with rest interval of 2 min in between. Soleus and super vastus lateralis (SVL) muscles mRNA were analyzed by real-time RT-PCR. SVL FOXO1 mRNA levels increased by 3.92-fold in the AEE and decreased 0.56-fold in the CEE group and were not significant in soleus muscle. In soleus muscle, myosin heavy chain (MHC) IIa, IIx, and IIb decreased in the AEE group and MHC IIa and IIx decreased in the CEE group. In SVL muscle, MHC I, IIa, and IIx increased in the AEE group and MHC IIa and IIX increased in the CEE group. In summary, both acute and chronic eccentric exercise could lead to change in FOXO1 mRNA only in fast SVL muscle of rat and so could induce fiber-type transition in both muscles regardless of changes in expression of FOXO1. So, oxidative stress can play important role in change of FOXO1.

  10. Relationship of primary and secondary myogenesis to fiber type development in embryonic chick muscle.

    PubMed

    Fredette, B J; Landmesser, L T

    1991-01-01

    The formation of fast and slow myotubes was investigated in embryonic chick muscle during primary and secondary myogenesis by immunocytochemistry for myosin heavy chain and Ca2(+)-ATPase. When antibodies to fast or slow isoforms of these two molecules were used to visualize myotubes in the posterior iliotibialis and iliofibularis muscles, one of the isoforms was observed in all primary and secondary myotubes until very late in development. In the case of myosin, the fast antibody stained virtually all myotubes until after stage 40, when fast myosin expression was lost in the slow myotubes of the iliofibularis. In the case of Ca2(+)-ATPase, the slow antibody also stained all myotubes until after stage 40, when staining was lost in secondary myotubes and in the fast primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis. In contrast, the antibodies against slow muscle myosin heavy chain and fast muscle Ca2(+)-ATPase stained mutually exclusive populations of myotubes at all developmental stages investigated. During primary myogenesis, fast Ca2(+)-ATPase staining was restricted to the primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis, whereas slow myosin heavy chain staining was confined to all of the primary myotubes of the slow region of the iliofibularis. During secondary myogenesis, the fast Ca2(+)-ATPase antibody stained nearly all secondary myotubes, while primaries in the slow region of the iliofibularis remained negative. Thus, in the slow region of the iliofibularis muscle, these two antibodies could be used in combination to distinguish primary and secondary myotubes. EM analysis of staining with the fast Ca2(+)-ATPase antibody confirmed that it recognizes only secondary myotubes in this region. This study establishes that antibodies to slow myosin heavy chain and fast Ca2(+)-ATPase are suitable markers for selective labeling of primary and secondary myotubes in the iliofibularis; these

  11. Glycolytic-to-oxidative fiber-type switch and mTOR signaling activation are early-onset features of SBMA muscle modified by high-fat diet.

    PubMed

    Rocchi, Anna; Milioto, Carmelo; Parodi, Sara; Armirotti, Andrea; Borgia, Doriana; Pellegrini, Matteo; Urciuolo, Anna; Molon, Sibilla; Morbidoni, Valeria; Marabita, Manuela; Romanello, Vanina; Gatto, Pamela; Blaauw, Bert; Bonaldo, Paolo; Sambataro, Fabio; Robins, Diane M; Lieberman, Andrew P; Sorarù, Gianni; Vergani, Lodovica; Sandri, Marco; Pennuto, Maria

    2016-07-01

    Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by the expansion of a polyglutamine tract in the androgen receptor (AR). The mechanism by which expansion of polyglutamine in AR causes muscle atrophy is unknown. Here, we investigated pathological pathways underlying muscle atrophy in SBMA knock-in mice and patients. We show that glycolytic muscles were more severely affected than oxidative muscles in SBMA knock-in mice. Muscle atrophy was associated with early-onset, progressive glycolytic-to-oxidative fiber-type switch. Whole genome microarray and untargeted lipidomic analyses revealed enhanced lipid metabolism and impaired glycolysis selectively in muscle. These metabolic changes occurred before denervation and were associated with a concurrent enhancement of mechanistic target of rapamycin (mTOR) signaling, which induced peroxisome proliferator-activated receptor γ coactivator 1 alpha (PGC1α) expression. At later stages of disease, we detected mitochondrial membrane depolarization, enhanced transcription factor EB (TFEB) expression and autophagy, and mTOR-induced protein synthesis. Several of these abnormalities were detected in the muscle of SBMA patients. Feeding knock-in mice a high-fat diet (HFD) restored mTOR activation, decreased the expression of PGC1α, TFEB, and genes involved in oxidative metabolism, reduced mitochondrial abnormalities, ameliorated muscle pathology, and extended survival. These findings show early-onset and intrinsic metabolic alterations in SBMA muscle and link lipid/glucose metabolism to pathogenesis. Moreover, our results highlight an HFD regime as a promising approach to support SBMA patients.

  12. Long-Term Effects of Botulinum Toxin Complex Type A Injection on Mechano- and Metabo-Sensitive Afferent Fibers Originating from Gastrocnemius Muscle.

    PubMed

    Caron, Guillaume; Marqueste, Tanguy; Decherchi, Patrick

    2015-01-01

    The aim of the present study was to investigate long term effects of motor denervation by botulinum toxin complex type A (BoNT/A) from Clostridium Botulinum, on the afferent fibers originating from the gastrocnemius muscle of rats. Animals were divided in 2 experimental groups: 1) untreated animals acting as control and 2) treated animals in which the toxin was injected in the left muscle, the latter being itself divided into 3 subgroups according to their locomotor recovery with the help of a test based on footprint measurements of walking rats: i) no recovery (B0), ii) 50% recovery (B50) and iii) full recovery (B100). Then, muscle properties, metabosensitive afferent fiber responses to potassium chloride (KCl) and lactic acid injections and Electrically-Induced Fatigue (EIF), and mechanosensitive responses to tendon vibrations were measured. At the end of the experiment, rats were killed and the toxin injected muscles were weighted. After toxin injection, we observed a complete paralysis associated to a loss of force to muscle stimulation and a significant muscle atrophy, and a return to baseline when the animals recover. The response to fatigue was only decreased in the B0 group. The responses to KCl injections were only altered in the B100 groups while responses to lactic acid were altered in the 3 injected groups. Finally, our results indicated that neurotoxin altered the biphasic pattern of response of the mechanosensitive fiber to tendon vibrations in the B0 and B50 groups. These results indicated that neurotoxin injection induces muscle afferent activity alterations that persist and even worsen when the muscle has recovered his motor activity.

  13. Long-Term Effects of Botulinum Toxin Complex Type A Injection on Mechano- and Metabo-Sensitive Afferent Fibers Originating from Gastrocnemius Muscle

    PubMed Central

    Caron, Guillaume; Marqueste, Tanguy; Decherchi, Patrick

    2015-01-01

    The aim of the present study was to investigate long term effects of motor denervation by botulinum toxin complex type A (BoNT/A) from Clostridium Botulinum, on the afferent fibers originating from the gastrocnemius muscle of rats. Animals were divided in 2 experimental groups: 1) untreated animals acting as control and 2) treated animals in which the toxin was injected in the left muscle, the latter being itself divided into 3 subgroups according to their locomotor recovery with the help of a test based on footprint measurements of walking rats: i) no recovery (B0), ii) 50% recovery (B50) and iii) full recovery (B100). Then, muscle properties, metabosensitive afferent fiber responses to potassium chloride (KCl) and lactic acid injections and Electrically-Induced Fatigue (EIF), and mechanosensitive responses to tendon vibrations were measured. At the end of the experiment, rats were killed and the toxin injected muscles were weighted. After toxin injection, we observed a complete paralysis associated to a loss of force to muscle stimulation and a significant muscle atrophy, and a return to baseline when the animals recover. The response to fatigue was only decreased in the B0 group. The responses to KCl injections were only altered in the B100 groups while responses to lactic acid were altered in the 3 injected groups. Finally, our results indicated that neurotoxin altered the biphasic pattern of response of the mechanosensitive fiber to tendon vibrations in the B0 and B50 groups. These results indicated that neurotoxin injection induces muscle afferent activity alterations that persist and even worsen when the muscle has recovered his motor activity. PMID:26485650

  14. Regeneration of frog twitch and slow muscle fibers after mincing.

    PubMed

    Schmidt, H; Emser, W

    1985-10-01

    Iliofibularis muscles of Rana temporaria were minced and allowed to regenerate in the iliofibularis or the sartorius bed of the same frog. Regenerated muscles were examined for the presence of slow muscle fibers using electrophysiologic, histochemical, and contractile parameters. Muscle regeneration from sartorius mince was also studied. Regeneration was more successful from iliofibularis than from sartorius mince, and the iliofibularis bed was more favorable for regeneration than the sartorius bed for both types of muscle. Twitch fibers regenerated within a few months, but slow fibers could not be identified earlier than 14 months after muscle destruction. Slow muscle fibers regenerated only from iliofibularis mince, both orthotopically and heterotopically. All regenerates capable of maintaining a K-contracture contained histochemically identified slow fibers; the membrane properties of electrophysiologically identified slow fibers were normal. It is concluded that slow muscle fibers regenerate only from the remnants of a muscle that contains slow fibers. The results are discussed with respect to the role of innervating nerve fibers.

  15. Aging of skeletal muscle fibers.

    PubMed

    Miljkovic, Natasa; Lim, Jae-Young; Miljkovic, Iva; Frontera, Walter R

    2015-04-01

    Aging has become an important topic for scientific research because life expectancy and the number of men and women in older age groups have increased dramatically in the last century. This is true in most countries of the world including the Republic of Korea and the United States. From a rehabilitation perspective, the most important associated issue is a progressive decline in functional capacity and independence. Sarcopenia is partly responsible for this decline. Many changes underlying the loss of muscle mass and force-generating capacity of skeletal muscle can be understood at the cellular and molecular levels. Muscle size and architecture are both altered with advanced adult age. Further, changes in myofibers include impairments in several physiological domains including muscle fiber activation, excitation-contraction coupling, actin-myosin cross-bridge interaction, energy production, and repair and regeneration. A thorough understanding of these alterations can lead to the design of improved preventative and rehabilitative interventions, such as personalized exercise training programs.

  16. Role of estrogen on skeletal muscle mitochondrial function in ovariectomized rats: a time course study in different fiber types.

    PubMed

    Cavalcanti-de-Albuquerque, J P A; Salvador, I C; Martins, Eduarda Lopes; Jardim-Messeder, D; Werneck-de-Castro, J P S; Galina, A; Carvalho, D P

    2014-04-01

    Postmenopausal women are prone to develop obesity and insulin resistance, which might be related to skeletal muscle mitochondrial dysfunction. In a rat model of ovariectomy (OVX), skeletal muscle mitochondrial function was examined at short- and long-term periods after castration. Mitochondrial parameters in the soleus and white gastrocnemius muscle fibers were analyzed. Three weeks after surgery, there were no differences in coupled mitochondrial respiration (ATP synthesis) with pyruvate, malate, and succinate; proton leak respiration; or mitochondrial reactive oxygen species production. However, after 3 wk of OVX, the soleus and white gastrocnemius muscles of the OVX animals showed a lower use of palmitoyl-carnitine and glycerol-phosphate substrates, respectively, and decreased peroxisome proliferator-activated receptor-γ coactivator-1α expression. Estrogen replacement reverted all of these phenotypes. Eight weeks after OVX, ATP synthesis was lower in the soleus and white gastrocnemius muscles of the OVX animals than in the sham-operated and estrogen-treated animals; however, when normalized by citrate synthase activity, these differences disappeared, indicating a lower muscle mitochondria content. No differences were observed in the proton leak parameter. Mitochondrial alterations did not impair the treadmill exercise capacity of the OVX animals. However, blood lactate levels in the OVX animals were higher after the physical test, indicating a compensatory extramitochondrial ATP synthesis system, but this phenotype was reverted by estrogen replacement. These results suggest early mitochondrial dysfunction related to lipid substrate use, which could be associated with the development of the overweight phenotype of ovariectomized animals.

  17. Effects of Two Different Weight Training Programs on Swimming Performance and Muscle Enzyme Activities and Fiber Type.

    PubMed

    Belfry, Glen R; Noble, Earl G; Taylor, Albert W

    2016-02-01

    The effects of 2 different weight training programs incorporating bench press (BP) and pullover (PO) exercises on swimming performance, power, enzyme activity, and fiber type distribution were studied on 16 men (age = 23 ± 4 years). A 30-second group (n = 6) performed up to 20 repetitions of BP and PO in 30 seconds. The 2-minute group (n = 6) performed a maximum of 80 repetitions of BP and PO in 2 minutes. As participants reached the prescribed 20 or 80 repetitions, the weight was increased 4.5 kg. A third group (n = 4) served as nontraining controls. Exercise groups trained 3 times per week for 6 weeks. Maximal effort swims of 50 and 200 yd were performed before and after training. Training resulted in increases in work on both exercises in both groups pre- to post-training (BP 30 seconds, 722 ± 236-895 ± 250 kg; PO 30 seconds, 586 ± 252-1,090 ± 677 kg; and BP 2 minutes, 1,530 ± 414-1,940 ± 296; PO 2 minutes, 1,212 ± 406-2,348 ± 194, p ≤ 0.05). Swim performances of the 30-second group improved for both the 50-yd (32.0 ± 6.9 seconds, 30.0 ± 5.9 seconds, p ≤ 0.05) and 200-yd swims 200.0 ± 54 seconds, 182 ± 45.1 seconds (p ≤ 0.05), whereas 2-minute training improved only the 200-yd swim (198.3 ± 32.3 seconds, 186.2 ± 32.2 seconds). No changes in swim performance were observed for the control group. Triceps muscle succinate dehydrogenase activities increased (pre 3.48 ± 1.1 μmol · g(-1) wet weight per minute, post 6.25 ± 1.5 μmoles · g(-1) wet weight per minute, p ≤ 0.05) in only the 30-second training group, whereas phosphofructokinase activities and fiber type distribution did not change in either training group. This study has demonstrated that a 30-second 20-repetition weight training program, specific to the swimming musculature without concurrent swim training, improves swimming performances at both 50- and 200-yd distances.

  18. Aged Muscle Demonstrates Fiber-Type Adaptations in Response to Mechanical Overload, in the Absence of Myofiber Hypertrophy, Independent of Satellite Cell Abundance.

    PubMed

    Lee, Jonah D; Fry, Christopher S; Mula, Jyothi; Kirby, Tyler J; Jackson, Janna R; Liu, Fujun; Yang, Lin; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2016-04-01

    Although sarcopenia, age-associated loss of muscle mass and strength, is neither accelerated nor exacerbated by depletion of muscle stem cells, satellite cells, we hypothesized that adaptation in sarcopenic muscle would be compromised. To test this hypothesis, we depleted satellite cells with tamoxifen treatment of Pax7(CreER)-DTA mice at 4 months of age, and 20 months later subjected the plantaris muscle to 2 weeks of mechanical overload. We found myofiber hypertrophy was impaired in aged mice regardless of satellite cell content. Even in the absence of growth, vehicle-treated mice mounted a regenerative response, not apparent in tamoxifen-treated mice. Further, myonuclear accretion occurred in the absence of growth, which was prevented by satellite cell depletion, demonstrating that myonuclear addition is insufficient to drive myofiber hypertrophy. Satellite cell depletion increased extracellular matrix content of aged muscle that was exacerbated by overload, potentially limiting myofiber growth. These results support the idea that satellite cells regulate the muscle environment, and that their loss during aging may contribute to fibrosis, particularly during periods of remodeling. Overload induced a fiber-type composition improvement, independent of satellite cells, suggesting that aged muscle is very responsive to exercise-induced enhancement in oxidative capacity, even with an impaired hypertrophic response.

  19. Molecular Mechanisms Regulating Muscle Fiber Composition Under Microgravity

    NASA Technical Reports Server (NTRS)

    Rosenthal, Nadia A.

    1999-01-01

    The overall goal of this project is to reveal the molecular mechanisms underlying the selective and debilitating atrophy of specific skeletal muscle fiber types that accompanies sustained conditions of microgravity. Since little is currently known about the regulation of fiber-specific gene expression programs in mammalian muscle, elucidation of the basic mechanisms of fiber diversification is a necessary prerequisite to the generation of therapeutic strategies for attenuation of muscle atrophy on earth or in space. Vertebrate skeletal muscle development involves the fusion of undifferentiated mononucleated myoblasts to form multinucleated myofibers, with a concomitant activation of muscle-specific genes encoding proteins that form the force-generating contractile apparatus. The regulatory circuitry controlling skeletal muscle gene expression has been well studied in a number of vertebrate animal systems. The goal of this project has been to achieve a similar level of understanding of the mechanisms underlying the further specification of muscles into different fiber types, and the role played by innervation and physical activity in the maintenance and adaptation of different fiber phenotypes into adulthood. Our recent research on the genetic basis of fiber specificity has focused on the emergence of mature fiber types and have implicated a group of transcriptional regulatory proteins, known as E proteins, in the control of fiber specificity. The restriction of E proteins to selected muscle fiber types is an attractive hypothetical mechanism for the generation of muscle fiber-specific patterns of gene expression. To date our results support a model wherein different E proteins are selectively expressed in muscle cells to determine fiber-restricted gene expression. These studies are a first step to define the molecular mechanisms responsible for the shifts in fiber type under conditions of microgravity, and to determine the potential importance of E proteins as

  20. Decreased Peak Expiratory Flow Associated with Muscle Fiber-Type Switching in Spinal and Bulbar Muscular Atrophy

    PubMed Central

    Yamada, Shinichiro; Hashizume, Atsushi; Hijikata, Yasuhiro; Inagaki, Tomonori; Suzuki, Keisuke; Kondo, Naohide; Kawai, Kaori; Noda, Seiya; Nakanishi, Hirotaka; Banno, Haruhiko; Hirakawa, Akihiro; Koike, Haruki; Halievski, Katherine; Jordan, Cynthia L.; Katsuno, Masahisa; Sobue, Gen

    2016-01-01

    The aim of this study was to characterize the respiratory function profile of subjects with spinal and bulbar muscular atrophy (SBMA), and to explore the underlying pathological mechanism by comparing the clinical and biochemical indices of this disease with those of amyotrophic lateral sclerosis (ALS). We enrolled male subjects with SBMA (n = 40) and ALS (n = 25) along with 15 healthy control subjects, and assessed their respiratory function, motor function, and muscle strength. Predicted values of peak expiratory flow (%PEF) and forced vital capacity were decreased in subjects with SBMA compared with controls. In SBMA, both values were strongly correlated with the trunk subscores of the motor function tests and showed deterioration relative to disease duration. Compared with activities of daily living (ADL)-matched ALS subjects, %PEF, tongue pressure, and grip power were substantially decreased in subjects with SBMA. Both immunofluorescence and RT-PCR demonstrated a selective decrease in the expression levels of the genes encoding the myosin heavy chains specific to fast-twitch fibers in SBMA subjects. The mRNA levels of peroxisome proliferator-activated receptor gamma coactivator 1-alpha and peroxisome proliferator-activated receptor delta were up-regulated in SBMA compared with ALS and controls. In conclusion, %PEF is a disease-specific respiratory marker for the severity and progression of SBMA. Explosive muscle strength, including %PEF, was selectively affected in subjects with SBMA and was associated with activation of the mitochondrial biogenesis-related molecular pathway in skeletal muscles. PMID:28005993

  1. Decreased Peak Expiratory Flow Associated with Muscle Fiber-Type Switching in Spinal and Bulbar Muscular Atrophy.

    PubMed

    Yamada, Shinichiro; Hashizume, Atsushi; Hijikata, Yasuhiro; Inagaki, Tomonori; Suzuki, Keisuke; Kondo, Naohide; Kawai, Kaori; Noda, Seiya; Nakanishi, Hirotaka; Banno, Haruhiko; Hirakawa, Akihiro; Koike, Haruki; Halievski, Katherine; Jordan, Cynthia L; Katsuno, Masahisa; Sobue, Gen

    2016-01-01

    The aim of this study was to characterize the respiratory function profile of subjects with spinal and bulbar muscular atrophy (SBMA), and to explore the underlying pathological mechanism by comparing the clinical and biochemical indices of this disease with those of amyotrophic lateral sclerosis (ALS). We enrolled male subjects with SBMA (n = 40) and ALS (n = 25) along with 15 healthy control subjects, and assessed their respiratory function, motor function, and muscle strength. Predicted values of peak expiratory flow (%PEF) and forced vital capacity were decreased in subjects with SBMA compared with controls. In SBMA, both values were strongly correlated with the trunk subscores of the motor function tests and showed deterioration relative to disease duration. Compared with activities of daily living (ADL)-matched ALS subjects, %PEF, tongue pressure, and grip power were substantially decreased in subjects with SBMA. Both immunofluorescence and RT-PCR demonstrated a selective decrease in the expression levels of the genes encoding the myosin heavy chains specific to fast-twitch fibers in SBMA subjects. The mRNA levels of peroxisome proliferator-activated receptor gamma coactivator 1-alpha and peroxisome proliferator-activated receptor delta were up-regulated in SBMA compared with ALS and controls. In conclusion, %PEF is a disease-specific respiratory marker for the severity and progression of SBMA. Explosive muscle strength, including %PEF, was selectively affected in subjects with SBMA and was associated with activation of the mitochondrial biogenesis-related molecular pathway in skeletal muscles.

  2. miR-30e is negatively regulated by myostatin in skeletal muscle and is functionally related to fiber-type composition.

    PubMed

    Jia, Haixue; Zhao, Yixia; Li, Tingting; Zhang, Yong; Zhu, Dahai

    2017-03-17

    Myostatin (MSTN) negatively regulates skeletal myogenesis in which microRNAs (miRNAs) also play critical roles. Using miRNA microarrays of skeletal muscle from MSTN-knockout (MSTN-/-) mice, we recently showed that miR-431 is regulated by MSTN signaling. To identify additional miRNAs regulated by MSTN, we re-analyzed these miRNA arrays and validated their expression by quantitative RT-PCR. Herein, we demonstrated that miR-30e was significantly upregulated in skeletal muscle of MSTN-/- mice compared with that of the wild-type littermates. Importantly, the predicted targets of miR-30e are functionally involved in myocyte differentiation and fiber-type formation. Using luciferase reporter gene assays, we further showed that peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (Pgc1α), is a direct target of miR-30e. Overexpression of miR-30e in C2C12 cells significantly decreased Pgc1α and increased type II form of myosin heavy chain gene expression, suggesting that miR-30e functionally associates with glycolytic myofiber formation. Thus, our data indicate that the altered fiber-type composition in MSTN-/- mice are attributable in part to deregulated expression of miR-30e.

  3. Effects of training and testosterone on muscle fiber types and locomotor performance in male six-lined racerunners (Aspidoscelis sexlineata).

    PubMed

    O'Connor, Jennifer L; McBrayer, Lance D; Higham, Timothy E; Husak, Jerry F; Moore, Ignacio T; Rostal, David C

    2011-01-01

    Testosterone (T) is thought to affect a variety of traits important for fitness, including coloration, the size of sexual ornaments, aggression, and locomotor performance. Here, we investigated the effects of experimentally elevated T and locomotor training on muscle physiology and running performance in a nonterritorial male lizard species (Aspidoscelis sexlineata). Additionally, several morphological attributes were quantified to examine other characters that are likely affected by T and/or a training regimen. Neither training alone nor training with T supplementation resulted in increased locomotor performance. Instead, we found that T and training resulted in a decrease in each of three locomotor performance variables as well as in hematocrit, ventral coloration, and testis size. Strikingly, neither the size nor the fiber composition of the iliofibularis or gastrocnemius muscles was different among the two treatments or a group of untrained control animals. Hence, the relationships among T, training, and associated characters are not clear. Our results offer important insights for those hoping to conduct laboratory manipulations on nonmodel organisms and highlight the challenges of studying both training effects and the effects of steroid hormones on locomotor performance.

  4. Heterogeneity of fiber characteristics in the rat masseter and digastric muscles.

    PubMed

    Sano, R; Tanaka, E; Korfage, J A M; Langenbach, G E J; Kawai, Nobuhiko; van Eijden, T M G J; Tanne, K

    2007-10-01

    The functional requirements in muscle use are related to the fiber type composition of the muscles and the cross-sectional area of the individual fibers. We investigated the heterogeneity in the fiber type composition and fiber cross-sectional area in two muscles with an opposing function, namely the digastric and masseter muscles (n = 5 for each muscle) of adult male rats, by means of immunohistochemical staining according to their myosin heavy chain (MyHC) content. The digastric and masseter muscles were taken from Wistar strain male rats 10 weeks old. In the masseter six predefined sample locations were examined; in the digastric four. Most regions showed dominant proportions of type IIA and IIX fibers. However, both muscles also revealed a regional heterogeneity in their fiber type distribution. In the digastric, type I fibers were detected only at the central and deep areas of the anterior and posterior belly, respectively. Meanwhile, the peripheral area of the anterior belly contained a higher proportion of type IIB fibers. In the masseter, the type I fibers were absent. In the superficial masseter the distribution of IIA and IIB fibers was significantly different between the superior and inferior regions. In the deep masseter, regional differences were observed among all four examined areas, of which the posterolateral region contained the highest proportion of type IIB fibers. The cross-sectional areas of type IIB fibers were always the largest, followed by the type IIX and IIA fibers. Only a few differences in cross-sectional area of corresponding fiber types were detected between the various sites. In conclusion, the masseter and digastric muscles showed an obvious heterogeneity of fiber type composition and fiber cross-sectional area. Their heterogeneity reflects the complex role of the both muscles during function. This detailed description of the fiber type composition can serve as a reference for future studies examining the muscular adaptations after

  5. Changes in oxygenation and phosphocreatine during exercise and recovery in relation to fiber types and capillary supply in human skeletal muscle

    NASA Astrophysics Data System (ADS)

    Hamaoka, Takatumi; Mizuno, Masano; Osada, Takuya; Ratkevicius, Aivaras; Nielsen, Alexander N.; Nakagawa, Yoshinao; Katsumura, Toshihito; Shimomitsu, Teruichi; Quistorff, Bjorn

    1997-12-01

    The purpose of this study was to examine the relationship between histochemical characteristics obtained from the gastrocnemius and changes in muscle energetics. Muscle oxygenation was determined by near infrared spectroscopy, and phosphocreatine (PCr) by 31-phosphorus magnetic resonance spectroscopy (31P-MRS) during a submaximal plantar flexion exercise and recovery. The relative occurrence (%) of slow-twitch fibers (ST), fast-twitch oxidative fibers (FTa), fast-twitch glycolytic fibers (FTb), and the number of capillaries per fiber (Cap/Fiber) were also determined. The sum of %ST and %FTa (%ST + %FTa) was 85.8 +/- 8.74% (mean +/- SD), while the number of Cap/Fiber was 2.52 +/- 0.63. The initial rate of deoxygenation (Ratedeoxy) at the beginning of the exercise was 2.43 +/- 0.95 %(DOT)sec-1. The time constants (Tc) for the recovery of PCr and muscle oxygenation after exercise were 22.1 +/- 6.3 sec. and 20.3 +/- 13.6 sec., respectively. The %ST + FTa, and the number of Cap/Fiber were each positively correlated to the Ratedeoxy (P < 0.05). The %ST + %FTa, and the number of Cap/Fiber were negatively correlated to the Tc for PCr recovery (P < 0.05), but not correlated to that for muscle oxygenation recovery. In conclusion, the Ratedeoxy during localized submaximal exercise, and the Tc for PCr recovery are indicators of the muscle's oxidative capacity.

  6. Changes in oxygenation and phosphocreatine during exercise and recovery in relation to fiber types and capillary supply in human skeletal muscle

    NASA Astrophysics Data System (ADS)

    Hamaoka, Takatumi; Mizuno, Masano; Osada, Takuya; Ratkevicius, Aivaras; Nielsen, Alexander N.; Nakagawa, Yoshinao; Katsumura, Toshihito; Shimomitsu, Teruichi; Quistorff, Bjorn

    1998-01-01

    The purpose of this study was to examine the relationship between histochemical characteristics obtained from the gastrocnemius and changes in muscle energetics. Muscle oxygenation was determined by near infrared spectroscopy, and phosphocreatine (PCr) by 31-phosphorus magnetic resonance spectroscopy (31P-MRS) during a submaximal plantar flexion exercise and recovery. The relative occurrence (%) of slow-twitch fibers (ST), fast-twitch oxidative fibers (FTa), fast-twitch glycolytic fibers (FTb), and the number of capillaries per fiber (Cap/Fiber) were also determined. The sum of %ST and %FTa (%ST + %FTa) was 85.8 +/- 8.74% (mean +/- SD), while the number of Cap/Fiber was 2.52 +/- 0.63. The initial rate of deoxygenation (Ratedeoxy) at the beginning of the exercise was 2.43 +/- 0.95 %(DOT)sec-1. The time constants (Tc) for the recovery of PCr and muscle oxygenation after exercise were 22.1 +/- 6.3 sec. and 20.3 +/- 13.6 sec., respectively. The %ST + FTa, and the number of Cap/Fiber were each positively correlated to the Ratedeoxy (P < 0.05). The %ST + %FTa, and the number of Cap/Fiber were negatively correlated to the Tc for PCr recovery (P < 0.05), but not correlated to that for muscle oxygenation recovery. In conclusion, the Ratedeoxy during localized submaximal exercise, and the Tc for PCr recovery are indicators of the muscle's oxidative capacity.

  7. Experiment K-7-21: Effect of Microgravity on 1: Metabolic Enzymes of Type 1 and Type 2 Muscle Fibers, and on 2: Metabolic Enzymes, Neurotransmitter Amino Acids, and Neurotransmitter Associated Enzymes in Selected Regions of the Central Nervous System. Part 1; Metabolic Enzymes of Individual Muscle Fibers

    NASA Technical Reports Server (NTRS)

    Lowry, O. H.; Ilyina-Kakueva, E. I.; Krasnov, I. B.; Carter, J. G.; Chi, M. M.-Y.; Choksi, R.; Manchester, J. K.; McDougal, D. B.; Nemeth, P. M.; Pusateri, M. E.

    1994-01-01

    Individual fibers of any given muscle vary widely in enzyme composition, a fact obscured when enzyme levels of whole muscle are measured. Therefore, the purpose of this part of the study was to assess the effects of microgravity and hind limb suspension on the enzyme patterns within a slow twitch muscle (soleus) and a fast twitch muscle (tibialis anterior).

  8. Adaptations of human skeletal muscle fibers to spaceflight

    NASA Technical Reports Server (NTRS)

    Day, M. Kathleen; Allen, David L.; Mohajerani, Laleh; Greenisen, Michael C.; Roy, Roland R.; Edgerton, V. Reggie

    1995-01-01

    Human skeletal muscle fibers seem to share most of the same interrelationships among myosin ATPase activity, myosin heavy chain (MHC) phenotype, mitochondrial enzyme activities, glycolytic enzyme activities, and cross-sectional area (CSA) as found in rat, cat, and other species. One difference seems to be that fast fibers with high mitochrondrial content occur less frequently in humans than in the rat or cat. Recently, we have reported that the type of MHC expressed and the size of the muscle fibers in humans that have spent 11 days in space change significantly. Specifically, about 8% more fibers express fast MHCs and all phenotypes atrophy in the vastus lateralis (VL) post compared to preflight. In the present paper we examine the relationships among the population of myonuclei, MHC type, and CSA of single human muscle fibers before and after spaceflight. These are the first data that define the relationship among the types of MHC expressed, myonuclei number, and myonuclei domain of single fibers in human muscle. We then compare these data to similar measures in the cat. In addition, the maximal torque that can be generated by the knee extensors and their fatigability before and after spaceflight are examined. These data provide some indication of the potential physiologica consequences of the muscle adaptations that occur in humans in response to spaceflight.

  9. Differential Responses of Soleus and Plantaris Muscle Fibers to Overloading

    NASA Astrophysics Data System (ADS)

    Kawano, Fuminori; Shibaguchi, Tsubasa; Ohira, Takashi; Nakai, Naoya; Ohira, Yoshinobu

    2013-02-01

    Responses of slow and fast fibers in soleus and plantaris muscles of adult rats to overloading by the tendon transection of synergists were studied. Overloading-related hypertrophy was noted in the slow fibers of plantaris and soleus, although the magnitude was greater in plantaris. Five genes with minor expression in slow soleus muscle were identified by microarray analysis. Base-line expressions of these genes in slow fibers of plantaris were also low. Further, repressive effects of overloading on these genes were seen in some fast fibers of plantaris, not in whole plantaris and soleus. The data suggested that the repression of particular genes might be related to the pronounced morphological response of fibers expressing type II, including I+II, myosin heavy chain (MyHC), although these genes with lower base-line expression in slow fibers did not respond to overloading.

  10. Fiber architecture of canine abdominal muscles.

    PubMed

    Boriek, Aladin M; Ortize, Jaime; Zhu, Deshen

    2002-02-01

    During respiration, abdominal muscles experience loads, not only in the muscle-fiber direction but also transverse to the fibers. We wondered whether the abdominal muscles exhibit a fiber architecture that is similar to the diaphragm muscle, and, therefore, we chose two adjacent muscles: the internal oblique (IO), with about the same muscle length as the diaphragm, and the transverse abdominis (TA), which is twice as long as the diaphragm. First, we used acetylcholinesterase staining to examine the distribution of neuromuscular junctions on both surfaces of the TA and IO muscles in six dogs. A maximum of four irregular bands of neuromuscular junctions crossed the IO, and as many as six bands crossed the TA, which is consistent with a discontinuous fiber architecture. In six additional dogs, we examined fiber architecture of these muscles by microdissecting 103 fascicles from the IO and 139 from the TA. Each fascicle contained between 20 and 30 muscle fibers. The mean length of nonspanning fibers (NSF) ranged from 2.8 +/- 0.3 cm in the IO to 4.3 +/- 0.5 cm in the TA, and the mean length of spanning fibers ranged from 4.3 +/- 0.5 cm in the IO to 7.6 +/- 1.4 cm in the TA. NSF accounted for 89.6 +/- 1.5% of all fibers dissected from the IO and 99.1 +/- 0.2% of all fibers dissected from the TA. The percentage of NSF with both ends tapered was 6.2 +/- 1.0 and 41.0 +/- 2.3% for IO and TA, respectively. These data show that fiber architecture in either IO or TA is discontinuous, with much more short-tapered fibers in the TA than in the IO. When abdominal muscles are submaximally activated, as during both normal expiration and maximal expiratory efforts, muscle force could be transmitted to the cell membrane and to the extracellular intramuscular connective tissue by shear linkage, presumably via structural transmembrane proteins.

  11. Muscle Transcriptional Profile Based on Muscle Fiber, Mitochondrial Respiratory Activity, and Metabolic Enzymes

    PubMed Central

    Liu, Xuan; Du, Yang; Trakooljul, Nares; Brand, Bodo; Muráni, Eduard; Krischek, Carsten; Wicke, Michael; Schwerin, Manfred; Wimmers, Klaus; Ponsuksili, Siriluck

    2015-01-01

    Skeletal muscle is a highly metabolically active tissue that both stores and consumes energy. Important biological pathways that affect energy metabolism and metabolic fiber type in muscle cells may be identified through transcriptomic profiling of the muscle, especially ante mortem. Here, gene expression was investigated in malignant hyperthermia syndrome (MHS)-negative Duroc and Pietrian (PiNN) pigs significantly differing for the muscle fiber types slow-twitch-oxidative fiber (STO) and fast-twitch-oxidative fiber (FTO) as well as mitochondrial activity (succinate-dependent state 3 respiration rate). Longissimus muscle samples were obtained 24 h before slaughter and profiled using cDNA microarrays. Differential gene expression between Duroc and PiNN muscle samples were associated with protein ubiquitination, stem cell pluripotency, amyloid processing, and 3-phosphoinositide biosynthesis and degradation pathways. In addition, weighted gene co-expression network analysis within both breeds identified several co-expression modules that were associated with the proportion of different fiber types, mitochondrial respiratory activity, and ATP metabolism. In particular, Duroc results revealed strong correlations between mitochondrion-associated co-expression modules and STO (r = 0.78), fast-twitch glycolytic fiber (r = -0.98), complex I (r=0.72) and COX activity (r = 0.86). Other pathways in the protein-kinase-activity enriched module were positively correlated with STO (r=0.93), while negatively correlated with FTO (r = -0.72). In contrast to PiNN, co-expression modules enriched in macromolecule catabolic process, actin cytoskeleton, and transcription activator activity were associated with fiber types, mitochondrial respiratory activity, and metabolic enzyme activities. Our results highlight the importance of mitochondria for the oxidative capacity of porcine muscle and for breed-dependent molecular pathways in muscle cell fibers. PMID:26681915

  12. Types of muscle tissue (image)

    MedlinePlus

    ... appear striated, and are under involuntary control. Smooth muscle fibers are located in walls of hollow visceral organs, except the heart, appear spindle-shaped, and are also under involuntary control. Skeletal ...

  13. SCA28: Novel Mutation in the AFG3L2 Proteolytic Domain Causes a Mild Cerebellar Syndrome with Selective Type-1 Muscle Fiber Atrophy.

    PubMed

    Svenstrup, Kirsten; Nielsen, Troels Tolstrup; Aidt, Frederik; Rostgaard, Nina; Duno, Morten; Wibrand, Flemming; Vinther-Jensen, Tua; Law, Ian; Vissing, John; Roos, Peter; Hjermind, Lena Elisabeth; Nielsen, Jørgen Erik

    2017-02-01

    The spinocerebellar ataxias (SCA) are a group of rare inherited neurodegenerative diseases characterized by slowly progressive cerebellar ataxia, resulting in unsteady gait, clumsiness, and dysarthria. The disorders are predominantly inherited in an autosomal dominant manner. Mutations in the gene AFG3L2 that encodes a subunit of the mitochondrial m-AAA protease have previously been shown to cause spinocerebellar ataxia type 28 (SCA28). Here, we present the clinical phenotypes of three patients from a family with autosomal dominant cerebellar ataxia and show by molecular genetics and in silico modelling that this is caused by a novel missense mutation in the AFG3L2 gene. Furthermore, we show, for the first time, fluorodeoxyglucose-positron emission tomography (FDG-PET) scans of the brain and selective type I fiber atrophy of skeletal muscle of SCA28 patients indicating non-nervous-system involvement in SCA28 as well.

  14. Proportions of myosin heavy chain mRNAs, protein isoforms and fiber types in the slow and fast skeletal muscles are maintained after alterations of thyroid status in rats.

    PubMed

    Soukup, T; Diallo, M

    2015-01-01

    Recently, we have established that slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles of euthyroid (EU) Lewis rats posses the same proportions between their four myosin heavy chain (MyHC) mRNAs, protein isoforms and fiber types as determined by real time RT-PCR, SDS-PAGE and 2-D stereological fiber type analysis, respectively. In the present paper we investigated if these proportions are maintained in adult Lewis rats with hyperthyroid (HT) and hypothyroid (HY) status. Although HT and HY states change MyHC isoform expression, results from all three methods showed that proportion between MyHC mRNA-1, 2a, -2x/d, -2b, protein isoforms MyHC-1, -2a, -2x/d, -2b and to lesser extent also fiber types 1, 2A, 2X/D, 2B were preserved in both SOL and EDL muscles. Furthermore, in the SOL muscle mRNA expression of slow MyHC-1 remained up to three orders higher compared to fast MyHC transcripts, which explains the predominance of MyHC-1 isoform and fiber type 1 even in HT rats. Although HT status led in the SOL to increased expression of MyHC-2a mRNA, MyHC-2a isoform and 2A fibers, it preserved extremely low expression of MyHC-2x and -2b mRNA and protein isoforms, which explains the absence of pure 2X/D and 2B fibers. HY status, on the other hand, almost completely abolished expression of all three fast MyHC mRNAs, MyHC protein isoforms and fast fiber types in the SOL muscle. Our data present evidence that a correlation between mRNA, protein content and fiber type composition found in EU status is also preserved in HT and HY rats.

  15. An evaluation of the reliability of muscle fiber cross-sectional area and fiber number measurements in rat skeletal muscle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: The reliability of estimating muscle fiber cross-sectional area (measure of muscle fiber size) and fiber number from only a subset of fibers in rat hindlimb muscle cross-sections has not been systematically evaluated. This study examined the variability in mean estimates of fiber cross-s...

  16. Molecular Mechanisms Regulating Muscle Fiber Composition Under Microgravity

    NASA Technical Reports Server (NTRS)

    Rosenthal, Nadia A.

    1999-01-01

    The overall goal of this project is to reveal the molecular mechanisms underlying the selective and debilitating atrophy of specific skeletal muscle fiber types that accompanies sustained conditions of microgravity. Since little is currently known about the regulation of fiber-specific gene expression programs in mammalian muscle, elucidation of the basic mechanisms of fiber diversification is a necessary prerequisite to the generation of therapeutic strategies for attenuation of muscle atrophy on earth or in space. Vertebrate skeletal muscle development involves the fusion of undifferentiated mononucleated myoblasts to form multinucleated myofibers, with a concomitant activation of muscle-specific genes encoding proteins that form the force-generating contractile apparatus. The regulatory circuitry controlling skeletal muscle gene expression has been well studied in a number of vertebrate animal systems. The goal of this project has been to achieve a similar level of understanding of the mechanisms underlying the further specification of muscles into different fiber types, and the role played by innervation and physical activity in the maintenance and adaptation of different fiber phenotypes into adulthood. Our recent research on the genetic basis of fiber specificity has focused on the emergence of mature fiber types and have implicated a group of transcriptional regulatory proteins, known as E proteins, in the control of fiber specificity. The restriction of E proteins to selected muscle fiber types is an attractive hypothetical mechanism for the generation of muscle fiber-specific patterns of gene expression. To date our results support a model wherein different E proteins are selectively expressed in muscle cells to determine fiber-restricted gene expression. These studies are a first step to define the molecular mechanisms responsible for the shifts in fiber type under conditions of microgravity, and to determine the potential importance of E proteins as

  17. Constant Fiber Number During Skeletal Muscle Atrophy and Modified Arachidonate Metabolism During Hypertrophy

    NASA Technical Reports Server (NTRS)

    Templeton, G.

    1985-01-01

    A previously documented shift from Type I to IIA predominance of the soleus muscle during rat suspension was further investigated to determine if this shift was by selective reduction of a single fiber type, simultaneous reduction and formation of fibers with different fiber types, or a transformation of fiber type by individual fibers. By partial acid digestion and dissection, average total soleus fiber number was found to be 3022 + or - 80 (SE) and 3008 + or - 64 before and after four-week suspension (n=12). Another area of current research was based on previous studies which indicate that prostaglandins are biosynthesized by skeletal muscle and evoke protein synthesis and degradation.

  18. Effect of swim exercise training on human muscle fiber function

    NASA Technical Reports Server (NTRS)

    Fitts, R. H.; Costill, D. L.; Gardetto, P. R.

    1989-01-01

    The effect of swim exercise training on the human muscle fiber function was investigated in swimmers trained in a typical collegiate swim-training program followed by an intensified 10-day training period. The measured parameters included the peak tension (P0), negative log molar Ca(2+) concentration (pCa)-force, and maximal shortening speed (Vmax) of the slow-twitch type I and fast-twitch type II fibers obtained by biopsy from the deltoid muscle. The P0 values were found to be not altered after either the training or the 10-day intensive program. The type I fibers from the trained swimmers showed pCa-force curves shifted to the right, such that higher free Ca(2+) levels were required to elicit a given percent of P0. The training program significantly increased the Vmax in the type I fibers and decreased that of the type II fibers, and the 10-day intensive training produced a further significant decrease of the type II fibers.

  19. Contractile properties of single permeabilized muscle fibers from congenital cleft palates and normal palates of Spanish goats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A goat model in which cleft palate is induced by the plant alkaloid, anabasine was used to determine muscle fiber integrity of the levator veli palatine muscle. It was determined that the muscle fibers of the cleft palate-induced goats were primarily of the type 2 (fast fibers) which fatigue easil...

  20. Skeletal muscle fiber analysis by atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometric imaging at high mass and high spatial resolution.

    PubMed

    Tsai, Yu-Hsuan; Bhandari, Dhaka Ram; Garrett, Timothy J; Carter, Christy S; Spengler, Bernhard; Yost, Richard A

    2016-06-01

    Skeletal muscles are composed of heterogeneous muscle fibers with various fiber types. These fibers can be classified into different classes based on their different characteristics. MALDI mass spectrometric imaging (MSI) has been applied to study and visualize different metabolomics profiles of different fiber types. Here, skeletal muscles were analyzed by atmospheric pressure scanning microprobe MALDI-MSI at high spatial and high mass resolution.

  1. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth.

    PubMed

    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon; Vendelbo, Mikkel Holm; Paoli, Frank de; Vissing, Kristian

    2014-10-15

    Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type-specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P < 0.01) and exhibited a group difference from Ecc (P < 0.05), which did not increase. Myonuclei content in type I fibers increased in all groups (P < 0.01), while a specific accretion of myonuclei in type II fibers was observed in the Whey-Conc (P < 0.01) and Placebo-Ecc (P < 0.01) groups. Similarly, whereas type I fiber CSA increased independently of intervention (P < 0.001), type II fiber CSA increased exclusively with Whey-Conc (P < 0.01) and type II fiber hypertrophy correlated with whole muscle hypertrophy exclusively following Conc training (P < 0.01). In conclusion, isolated concentric knee extensor resistance training appears to constitute a stronger driver of SC content than eccentric resistance training while type II fiber hypertrophy was accentuated when combining concentric resistance training with whey protein supplementation.

  2. 20-Hydroxyecdysone increases fiber size in a muscle-specific fashion in rat.

    PubMed

    Tóth, Noémi; Szabó, András; Kacsala, Péter; Héger, Júlia; Zádor, Ernö

    2008-09-01

    20-Hydroxyecdysone (20E) is an ecdysteroid hormone that regulates moulting in insects. Interestingly, 20E is also found most abundantly in plant species and has anabolic effects in vertebrates, i.e. increasing muscle size without androgen influence. The effect of 20E on slow and fast fiber types of skeletal muscle has not been reported yet. Here we present that 20E affects the size (cross-sectional area, CSA) of the different fiber types in a muscle-specific manner. The effect on fiber size was modified by the distance from the site of the treatment and the presence of a regenerating soleus muscle in the animal. Besides the fiber size, 20E also increased the myonuclear number in the fibers of normal and regenerating muscles, suggesting the activation of satellite cells. According to our results 20E may provide an alternative for substitution of anabolic-androgenic steroids in therapeutic treatments against muscle atrophy.

  3. Calcium-activated force of human muscle fibers following a standardized eccentric contraction.

    PubMed

    Choi, Seung Jun; Widrick, Jeffrey J

    2010-12-01

    Peak Ca(2+)-activated specific force (force/fiber cross-sectional area) of human chemically skinned vastus lateralis muscle fiber segments was determined before and after a fixed-end contraction or an eccentric contraction of standardized magnitude (+0.25 optimal fiber length) and velocity (0.50 unloaded shortening velocity). Fiber myosin heavy chain (MHC) isoform content was assayed by SDS-PAGE. Posteccentric force deficit, a marker of damage, was similar for type I and IIa fibers but threefold greater for type IIa/IIx hybrid fibers. A fixed-end contraction had no significant effect on force. Multiple linear regression revealed that posteccentric force was explained by a model consisting of a fiber type-independent and a fiber type-specific component (r(2) = 0.91). Preeccentric specific force was directly associated with a greater posteccentric force deficit. When preeccentric force was held constant, type I and IIa fibers showed identical susceptibility to damage, while type IIa/IIx fibers showed a significantly greater force loss. This heightened sensitivity to damage was directly related to the amount of type IIx MHC in the hybrid fiber. Our model reveals a fiber-type sensitivity of the myofilament lattice or cytoskeleton to mechanical strain that can be described as follows: type IIa/IIx > type IIa = type I. If these properties extend to fibers in vivo, then alterations in the number of type IIa/IIx fibers may modify a muscle's susceptibility to eccentric damage.

  4. Metabolic and morphometric profile of muscle fibers in chronic hemodialysis patients

    PubMed Central

    Fournier, Mario; Wang, Huiyuan; Storer, Thomas W.; Casaburi, Richard; Cohen, Arthur H.; Kopple, Joel D.

    2012-01-01

    Muscle weakness and effort intolerance are common in maintenance hemodialysis (MHD) patients. This study characterized morphometric, histochemical, and biochemical properties of limb muscle in MHD patients compared with controls (CTL) with similar age, gender, and ethnicity. Vastus lateralis muscle biopsies were obtained from 60 MHD patients, 1 day after dialysis, and from 21 CTL. Muscle fiber types and capillaries were identified immunohistochemically. Individual muscle fiber cross-sectional areas (CSA) were quantified. Individual fiber oxidative capacities were determined (microdensitometric assay) to measure succinate dehydrogenase (SDH) activity. Mean CSAs of type I, IIA, and IIX fibers were 33, 26, and 28% larger in MHD patients compared with CTL. SDH activities for type I, IIA, and IIX fibers were reduced by 29, 40, and 47%, respectively, in MHD. Capillary to fiber ratio was increased by 11% in MHD. The number of capillaries surrounding individual fiber types were also increased (type I: 9%; IIA: 10%; IIX: 23%) in MHD patients. However, capillary density (capillaries per unit muscle fiber area) was reduced by 34% in MHD patients, compared with CTL. Ultrastuctural analysis revealed swollen mitochondria with dense matrix in MHD patients. These results highlight impaired oxidative capacity and capillarity in MHD patients. This would be expected to impair energy production as well as substrate and oxygen delivery and exchange and contribute to exercise intolerance. The enlarged CSA of muscle fibers may, in part, be accounted for by edema. We speculate that these changes contribute to reduce limb strength in MHD patients by reducing specific force. PMID:22016372

  5. Gene transcripts encoding hypoxia-inducible factor (HIF) exhibit tissue- and muscle fiber type-dependent responses to hypoxia and hypercapnic hypoxia in the Atlantic blue crab, Callinectes sapidus.

    PubMed

    Hardy, Kristin M; Follett, Chandler R; Burnett, Louis E; Lema, Sean C

    2012-09-01

    Hypoxia inducible factor (HIF) is a transcription factor that under low environmental oxygen regulates the expression of suites of genes involved in metabolism, angiogenesis, erythropoiesis, immune function, and growth. Here, we isolated and sequenced partial cDNAs encoding hif-α and arnt/hif-β from the Atlantic blue crab, Callinectes sapidus, an estuarine species that frequently encounters concurrent hypoxia (low O(2)) and hypercapnia (elevated CO(2)). We then examined the effects of acute exposure (1h) to hypoxia (H) and hypercapnic hypoxia (HH) on relative transcript abundance for hif-α and arnt/hif-β in different tissues (glycolytic muscle, oxidative muscle, hepatopancreas, gill, and gonads) using quantitative real-time RT-PCR. Our results indicate that hif-α and arnt/hif-β mRNAs were constitutively present under well-aerated normoxia (N) conditions in all tissues examined. Further, H and HH exposure resulted in both tissue-specific and muscle fiber type-specific effects on relative hif-α transcript abundance. In the gill and glycolytic muscle, relative hif-α mRNA levels were significantly lower under H and HH, compared to N, while no change (or a slight increase) was detected in oxidative muscle, hepatopancreas and gonadal tissues. H and HH did not affect relative transcript abundance for arnt/hif-β in any tissue or muscle fiber type. Thus, in crustaceans the HIF response to H and HH appears to involve changes in hif transcript abundance, with variation in hif-α and arnt/hif-β transcriptional dynamics occurring in both a tissue- and muscle fiber type-dependent manner.

  6. Intense interval training in healthy older adults increases skeletal muscle [(3)H]ouabain-binding site content and elevates Na(+),K(+)-ATPase α2 isoform abundance in Type II fibers.

    PubMed

    Wyckelsma, Victoria L; Levinger, Itamar; Murphy, Robyn M; Petersen, Aaron C; Perry, Ben D; Hedges, Christopher P; Anderson, Mitchell J; McKenna, Michael J

    2017-04-01

    Young adults typically adapt to intense exercise training with an increased skeletal muscle Na(+),K(+)-ATPase (NKA) content, concomitant with reduced extracellular potassium concentration [K(+)] during exercise and enhanced exercise performance. Whether these changes with longitudinal training occur in older adults is unknown and was investigated here. Fifteen older adults (69.4 ± 3.5 years, mean ± SD) were randomized to either 12 weeks of intense interval training (4 × 4 min at 90-95% peak heart rate), 3 days/week (IIT, n = 8); or no exercise controls (n = 7). Before and after training, participants completed an incremental cycle ergometer exercise test until a rating of perceived exertion of 17 (very hard) on a 20-point scale was attained, with measures of antecubital venous [K(+)]v Participants underwent a resting muscle biopsy prior to and at 48-72 h following the final training session. After IIT, the peak exercise work rate (25%), oxygen uptake (16%) and heart rate (6%) were increased (P < 0.05). After IIT, the peak exercise plasma [K(+)]v tended to rise (P = 0.07), while the rise in plasma [K(+)]v relative to work performed (nmol.L(-1)J(-1)) was unchanged. Muscle NKA content increased by 11% after IIT (P < 0.05). Single fiber measurements, increased in NKA α2 isoform in Type II fibers after IIT (30%, P < 0.05), with no changes to the other isoforms in single fibers or homogenate. Thus, intense exercise training in older adults induced an upregulation of muscle NKA, with a fiber-specific increase in NKA α2 abundance in Type II fibers, coincident with increased muscle NKA content and enhanced exercise performance.

  7. Respiratory muscle fiber remodeling in chronic hyperinflation: dysfunction or adaptation?

    PubMed

    Clanton, Thomas L; Levine, Sanford

    2009-07-01

    The diaphragm and other respiratory muscles undergo extensive remodeling in both animal models of emphysema and in human chronic obstructive pulmonary disease, but the nature of the remodeling is different in many respects. One common feature is a shift toward improved endurance characteristics and increased oxidative capacity. Furthermore, both animals and humans respond to chronic hyperinflation by diaphragm shortening. Although in rodent models this clearly arises by deletion of sarcomeres in series, the mechanism has not been proven conclusively in human chronic obstructive pulmonary disease. Unique characteristics of the adaptation in human diaphragms include shifts to more predominant slow, type I fibers, expressing slower myosin heavy chain isoforms, and type I and type II fiber atrophy. Although some laboratories report reductions in specific force, this may be accounted for by decreases in myosin heavy chain content as the muscles become more oxidative and more efficient. More recent findings have reported reductions in Ca(2+) sensitivity and reduced myofibrillar elastic recoil. In contrast, in rodent models of disease, there is no consistent evidence for loss of specific force, no consistent shift in fiber populations, and atrophy is predominantly seen only in fast, type IIX fibers. This review challenges the hypothesis that the adaptations in human diaphragm represent a form of dysfunction, secondary to systemic disease, and suggest that most findings can as well be attributed to adaptive processes of a complex muscle responding to unique alterations in its working environment.

  8. Muscle-fiber transdifferentiation in an experimental model of respiratory chain myopathy

    PubMed Central

    2012-01-01

    Introduction Skeletal muscle fiber composition and muscle energetics are not static and change in muscle disease. This study was performed to determine whether a mitochondrial myopathy is associated with adjustments in skeletal muscle fiber-type composition. Methods Ten rats were treated with zidovudine, an antiretroviral nucleoside reverse transcriptase inhibitor that induces a myopathy by interfering with mitochondrial functions. Soleus muscles were examined after 21 weeks of treatment. Ten untreated rats served as controls. Results Zidovudine induced a myopathy with mitochondrial DNA depletion, abnormalities in mitochondrial ultrastructure, and reduced cytochrome c oxidase activity. Mitochondrial DNA was disproportionally more diminished in type I compared with type II fibers, whereas atrophy predominated in type II fibers. Compared with those of controls, zidovudine-exposed soleus muscles contained an increased proportion (256%) of type II fibers, whereas neonatal myosin heavy chains remained repressed, indicating fiber-type transformation in the absence of regeneration. Microarray gene-expression analysis confirmed enhanced fast-fiber isoforms, repressed slow-fiber transcripts, and reduced neonatal fiber transcripts in the mitochondrial myopathy. Respiratory chain transcripts were diminished, whereas the enzymes of glycolysis and glycogenolysis were enhanced, indicating a metabolic adjustment from oxidative to glycolytic capacities. A coordinated regulation was found of transcription factors known to orchestrate type II fiber formation (upregulation of MyoD, Six1, Six2, Eya1, and Sox6, and downregulation of myogenin and ERRγ). Conclusions The type I to type II fiber transformation in mitochondrial myopathy implicates mitochondrial function as a new regulator of skeletal muscle fiber type. PMID:23107834

  9. Distribution of slow muscle fiber of muscle spindle in postnatal rat masseter muscle.

    PubMed

    Sato, Iwao; Imura, Kosuke; Miwa, Yoko; Ide, Yoshiaki; Murata, Megumi; Sunohara, Masataka

    2007-11-01

    We investigated the properties of the muscle spindle in the masseter muscle at an immunohistochemical level in rats fed for 6 weeks. Slow myosin heavy chain (MyHC) isoforms were measured and intrafusal fibers in the muscle spindle were studied to determine the relationship between the superficial and deep regions of rat masseter muscle after alternated feeding pattern. However, muscle spindles were found in both regions, mainly in the deep region of the posterior superficial region of masseter muscle. The total number of the slow fiber in the intrafusal fiber and number of muscle spindle in the deep region were high from 5 to 8 weeks old in spite of various dimensions of data such as diameter and the compositions of the intrafusal fiber. The relationship of the protein expression of slow MyHC in the two regions at 5 weeks old reversed five weeks later (10 weeks old). This period is an important stage because the mastication system in masseter muscle with muscle spindle may be changed during the alternated feeding pattern of suckling to mastication. The changes may be a marker of the feeding system and of the control by the tension receptor of muscle spindle in this stage of masseter muscle after postnatal development.

  10. Myoglobin plasma level related to muscle mass and fiber composition: a clinical marker of muscle wasting?

    PubMed

    Weber, Marc-André; Kinscherf, Ralf; Krakowski-Roosen, Holger; Aulmann, Michael; Renk, Hanna; Künkele, Annette; Edler, Lutz; Kauczor, Hans-Ulrich; Hildebrandt, Wulf

    2007-08-01

    Progressive muscle wasting is a central feature of cancer-related cachexia and has been recognized as a determinant of poor prognosis and quality of life. However, until now, no easily assessable clinical marker exists that allows to predict or to track muscle wasting. The present study evaluated the potential of myoglobin (MG) plasma levels to indicate wasting of large locomotor muscles and, moreover, to reflect the loss of MG-rich fiber types, which are most relevant for daily performance. In 17 cancer-cachectic patients (weight loss 22%) and 27 age- and gender-matched healthy controls, we determined plasma levels of MG and creatine kinase (CK), maximal quadriceps muscle cross-sectional area (CSA) by magnetic resonance imaging, muscle morphology and fiber composition in biopsies from the vastus lateralis muscle, body cell mass (BCM) by impedance technique as well as maximal oxygen uptake (VO(2)max). In cachectic patients, plasma MG, muscle CSA, BCM, and VO(2)max were 30-35% below control levels. MG showed a significant positive correlation to total muscle CSA (r = 0.65, p < 0.001) and to the CSA fraction formed by type 1 and 2a fibers (r = 0.80, p < 0.001). However, when adjusted for body height and age by multiple regression, MG yielded a largely improved prediction of total CSA (multiple r = 0.83, p < 0.001) and of fiber type 1 and 2a CSA (multiple r = 0.89, p < 0.001). The correlations between CK and these muscle parameters were weaker, and elevated CK values were observed in 20% of control subjects despite a prior abstinence from exercise for 5 days. In conclusion, plasma MG, when adjusted for anthropometric parameters unaffected by weight, may be considered as a novel marker of muscle mass (CSA) indicating best the mass of MG-rich type 1 and 2a fibers as well as VO(2)max as an important functional readout. CK plasma levels appear to be less reliable because prolonged increases are observed in even subclinical myopathies or after exercise. Notably, cancer

  11. Single muscle fiber gene expression with run taper.

    PubMed

    Murach, Kevin; Raue, Ulrika; Wilkerson, Brittany; Minchev, Kiril; Jemiolo, Bozena; Bagley, James; Luden, Nicholas; Trappe, Scott

    2014-01-01

    This study evaluated gene expression changes in gastrocnemius slow-twitch myosin heavy chain I (MHC I) and fast-twitch (MHC IIa) muscle fibers of collegiate cross-country runners (n = 6, 20±1 y, VO₂max = 70±1 ml•kg-1•min-1) during two distinct training phases. In a controlled environment, runners performed identical 8 kilometer runs (30:18±0:30 min:s, 89±1% HRmax) while in heavy training (∼72 km/wk) and following a 3 wk taper. Training volume during the taper leading into peak competition was reduced ∼50% which resulted in improved race times and greater cross-section and improved function of MHC IIa fibers. Single muscle fibers were isolated from pre and 4 hour post run biopsies in heavily trained and tapered states to examine the dynamic acute exercise response of the growth-related genes Fibroblast growth factor-inducible 14 (FN14), Myostatin (MSTN), Heat shock protein 72 (HSP72), Muscle ring-finger protein-1 (MURF1), Myogenic factor 6 (MRF4), and Insulin-like growth factor 1 (IGF1) via qPCR. FN14 increased 4.3-fold in MHC IIa fibers with exercise in the tapered state (P<0.05). MSTN was suppressed with exercise in both fiber types and training states (P<0.05) while MURF1 and HSP72 responded to running in MHC IIa and I fibers, respectively, regardless of training state (P<0.05). Robust induction of FN14 (previously shown to strongly correlate with hypertrophy) and greater overall transcriptional flexibility with exercise in the tapered state provides an initial molecular basis for fast-twitch muscle fiber performance gains previously observed after taper in competitive endurance athletes.

  12. Polarization-sensitive optical projection tomography for muscle fiber imaging

    PubMed Central

    Fang, Mengjie; Dong, Di; Zeng, Chaoting; Liang, Xiao; Yang, Xin; Arranz, Alicia; Ripoll, Jorge; Hui, Hui; Tian, Jie

    2016-01-01

    Optical projection tomography (OPT) is a tool used for three-dimensional imaging of millimeter-scale biological samples, with the advantage of exhibiting isotropic resolution typically in the micron range. OPT can be divided into two types: transmission OPT (tOPT) and emission OPT (eOPT). Compared with eOPT, tOPT discriminates different tissues based on their absorption coefficient, either intrinsic or after specific staining. However, it fails to distinguish muscle fibers whose absorption coefficients are similar to surrounding tissues. To circumvent this problem, in this article we demonstrate a polarization sensitive OPT system which improves the detection and 3D imaging of muscle fibers by using polarized light. We also developed image acquisition and processing protocols that, together with the system, enable the clear visualization of muscles. Experimental results show that the muscle fibers of diaphragm and stomach, difficult to be distinguished in regular tOPT, were clearly displayed in our system, proving its potential use. Moreover, polarization sensitive OPT was fused with tOPT to investigate the stomach tissue comprehensively. Future applications of polarization sensitive OPT could be imaging other fiber-like structures such as myocardium or other tissues presenting high optical anisotropy. PMID:26752330

  13. Congenital fiber type disproportion--30 years on.

    PubMed

    Clarke, Nigel F; North, Kathryn N

    2003-10-01

    Thirty years ago, M. H. Brooke coined the term "congenital fiber type disproportion" (CFTD) to describe 12 children who had clinical features of a congenital myopathy and relative type 1 fiber hypotrophy on muscle biopsy. It is now clear that this histological pattern can accompany a wide range of neurological disorders, leading to disillusionment with CFTD as a distinct nosological entity. To determine whether the CFTD has clinical utility as a diagnostic entity, we have reviewed the literature for cases of type 1 fiber hypotrophy and have used strict exclusion criteria to identify 67 cases of CFTD. Most patients presented at birth with weakness and hypotonia, had normal intelligence, and followed a static or improving clinical course. In 43% of families, more than 1 individual was affected. Failure to thrive was common and 25% of patients had contractures or spinal deformities. Bulbar weakness and ophthalmoplegia were less common and cardiac involvement was rare. Twenty-five percent followed a severe course and 10% had died at the time of reporting, all from respiratory failure. Ophthalmoplegia and facial and bulbar weakness were significantly associated with a poorer prognosis. The relatively homogeneous phenotype supports the retention of CFTD as a distinct diagnostic entity and familial occurrence suggests a genetic basis. Regarding the diagnosis of CFTD, we found no strong evidence that the minimum difference between type 1 and type 2 fiber sizes should be increased from 12% to 25%. We also list the other reported causes of relative type 1 fiber hypotrophy to aid their exclusion from CFTD.

  14. Graded Activation in Frog Muscle Fibers

    PubMed Central

    Costantin, L. L.; Taylor, S. R.

    1973-01-01

    The membrane potential of frog single muscle fibers in solutions containing tetrodotoxin was controlled with a two-electrode voltage clamp. Local contractions elicited by 100-ms square steps of depolarization were observed microscopically and recorded on cinefilm. The absence of myofibrillar folding with shortening to striation spacings below 1.95 µm served as a criterion for activation of the entire fiber cross section. With depolarizing steps of increasing magnitude, shortening occurred first in the most superficial myofibrils and spread inward to involve axial myofibrils as the depolarization was increased. In contractions in which the entire fiber cross section shortened actively, both the extent of shortening and the velocity of shortening at a given striation spacing could be graded by varying the magnitude of the depolarization step. The results provide evidence that the degree of activation of individual myofibrils can be graded with membrane depolarization. PMID:4540418

  15. Regional heterogeneity in muscle fiber strain: the role of fiber architecture

    PubMed Central

    Azizi, E.; Deslauriers, Amber R.

    2014-01-01

    The force, mechanical work and power produced by muscle fibers are profoundly affected by the length changes they undergo during a contraction. These length changes are in turn affected by the spatial orientation of muscle fibers within a muscle (fiber architecture). Therefore any heterogeneity in fiber architecture within a single muscle has the potential to cause spatial variation in fiber strain. Here we examine how the architectural variation within a pennate muscle and within a fusiform muscle can result in regional fiber strain heterogeneity. We combine simple geometric models with empirical measures of fiber strain to better understand the effect of architecture on fiber strain heterogeneity. We show that variation in pennation angle throughout a muscle can result in differences in fiber strain with higher strains being observed at lower angles of pennation. We also show that in fusiform muscles, the outer/superficial fibers of the muscle experience lower strains than central fibers. These results show that regional variation in mechanical output of muscle fibers can arise solely from architectural features of the muscle without the presence of any spatial variation in motor recruitment. PMID:25161626

  16. Contraction-induced injury to single permeabilized muscle fibers from normal and congenitally-clefted goat palates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A goat model in which cleft palate is induced by the plant alkaloid, anabasine was used to determine muscle fiber integrity of the levator veli palatine (LVP) muscle. It was determined that muscle fiber type, size, and sensitivity to contraction-induced injury was different between cleft palate ind...

  17. Comparison of Characteristics of Myosin Heavy Chain-based Fiber and Meat Quality among Four Bovine Skeletal Muscles

    PubMed Central

    Kim, Gap-Don; Yang, Han-Sul; Jeong, Jin-Yeon

    2016-01-01

    Muscle fiber characteristics account for meat quality and muscle fibers are mainly classified into three or more types according to their contractile and metabolic properties. However, the majority of previous studies on bovine skeletal muscle are based on myosin ATPase activity. In the present study, the differences in the characteristics of muscle fibers classified by the expression of myosin heavy chain (MHC) among four bovine skeletal muscles such as longissimus thoracis (LT), psoas major (PM), semimembranosus (SM) and semitendinosus (ST) and their relationships to beef quality were investigated. MHCs 2x, 2a and slow were identified by LC-MS/MS and IIX, IIA and I fiber types were classified. PM, which had the smallest size and highest density of fibers regardless of type, showed the highest myoglobin content, CIE L*, a*, b* and sarcomere length (p<0.05), whereas ST with the highest composition of IIX, showed high shear force and low sarcomere length (p<0.05). The correlation coefficients between muscle fiber characteristics and meat quality showed that type IIX is closely related to poor beef quality and that a high density of small-sized fibers is related to redness and tenderness. Therefore, the differences in meat quality between muscles can be explained by the differences in muscle fiber characteristics, and especially, the muscles with good quality are composed of more small-sized fibers regardless of fiber type. PMID:28115894

  18. [Comparison of force and shortening velocity in fast and slow rabbit muscle fibers at different temperatures].

    PubMed

    Kochubeĭ, P V; Bershitskiĭ, S Iu

    2014-01-01

    The temperature dependence of force, maximal shortening velocity and power of maximally activated single permeabilized fibers from fast and slow muscles of the rabbit were recorded in a temperature range from 10 to 35 degrees C with 5 degrees C step. It was found that temperature dependence of force of both types of fibers is identical. Averaged maximal shortening velocity in the slow fibers, unlike the fast fibers, had no statistically significant temperature dependence that is not in agreement with the data obtained on intact rat muscle fibers and in an in vitro motility assay. However maximal shortening velocity in each individual slow fiber did depend on temperature. The temperature dependence of power of the slow fibers was lower than that of the fast ones. Because of large data scattering the average temperature dependence of power of the slow fibers was significantly lower than that in individual slow fibers.

  19. Disodium cromoglycate protects dystrophin-deficient muscle fibers from leakiness.

    PubMed

    Marques, Maria Julia; Ventura Machado, Rafael; Minatel, Elaine; Santo Neto, Humberto

    2008-01-01

    In dystrophin-deficient fibers of mdx mice and in Duchenne dystrophy, the lack of dystrophin leads to sarcolemma breakdown and muscle degeneration. We verified that cromolyn, a mast-cell stabilizer agent, stabilized dystrophic muscle fibers using Evans blue dye as a marker of sarcolemma leakiness. Mdx mice (n=8; 14 days of age) received daily intraperitoneal injections of cromolyn (50 mg/kg body weight) for 15 days. Untreated mdx mice (n=8) were injected with saline. Cryostat cross-sections of the sternomastoid, tibialis anterior, and diaphragm muscles were stained with hematoxylin and eosin. Cromolyn dramatically reduced Evans blue dye-positive fibers in all muscles (P<0.05; Student's t-test) and led to a significant increase in the percentage of fibers with peripheral nuclei. This study supports the protective effects of cromolyn in dystrophic muscles and further indicates its action against muscle fiber leakiness in muscles that are differently affected by the lack of dystrophin.

  20. Diffusion-Tensor MRI Based Skeletal Muscle Fiber Tracking.

    PubMed

    Damon, Bruce M; Buck, Amanda K W; Ding, Zhaohua

    2011-11-01

    A skeletal muscle's function is strongly influenced by the internal organization and geometric properties of its fibers, a property known as muscle architecture. Diffusion-tensor magnetic resonance imaging-based fiber tracking provides a powerful tool for non-invasive muscle architecture studies, has three-dimensional sensitivity, and uses a fixed frame of reference. Significant advances have been made in muscle fiber tracking technology, including defining seed points for fiber tracking, quantitatively characterizing muscle architecture, implementing denoising procedures, and testing validity and repeatability. Some examples exist of how these data can be integrated with those from other advanced MRI and computational methods to provide novel insights into muscle function. Perspectives are offered regarding future directions in muscle diffusion-tensor imaging, including needs to develop an improved understanding for the microstructural basis for reduced and anisotropic diffusion, establish the best practices for data acquisition and analysis, and integrate fiber tracking with other physiological data.

  1. Skeletal muscle fiber, nerve, and blood vessel breakdown in space-flown rats

    NASA Technical Reports Server (NTRS)

    Riley, D. A.; Ilyina-Kakueva, E. I.; Ellis, S.; Bain, J. L.; Slocum, G. R.; Sedlak, F. R.

    1990-01-01

    Histochemical and ultrastructural analyses were performed postflight on hind limb skeletal muscles of rats orbited for 12.5 days aboard the unmanned Cosmos 1887 biosatellite and returned to Earth 2 days before sacrifice. The antigravity adductor longus (AL), soleus, and plantaris muscles atrophied more than the non-weight-bearing extensor digitorum longus, and slow muscle fibers were more atrophic than fast fibers. Muscle fiber segmental necrosis occurred selectively in the AL and soleus muscles; primarily, macrophages and neutrophils infiltrated and phagocytosed cellular debris. Granule-rich mast cells were diminished in flight AL muscles compared with controls, indicating the mast cell secretion contributed to interstitial tissue edema. Increased ubiquitination of disrupted myofibrils implicated ubiquitin in myofilament degradation. Mitochondrial content and succinic dehydrogenase activity were normal, except for subsarcolemmal decreases. Myofibrillar ATPase activity of flight AL muscle fibers shifted toward the fast type. Absence of capillaries and extravasation of red blood cells indicated failed microcirculation. Muscle fiber regeneration from activated satellite cells was detected. About 17% of the flight AL end plates exhibited total or partial denervation. Thus, skeletal muscle weakness associated with spaceflight can result from muscle fiber atrophy and segmental necrosis, partial motor denervation, and disruption of the microcirculation.

  2. Cycle Training Increased GLUT4 and Activation of mTOR in Fast Twitch Muscle Fibers

    PubMed Central

    Stuart, Charles A.; Howell, Mary E.A.; Baker, Jonathan D.; Dykes, Rhesa J.; Duffourc, Michelle M.; Ramsey, Michael W.; Stone, Michael H.

    2009-01-01

    Purpose To determine if cycle training of sedentary subjects would increase the expression of the principle muscle glucose transporters, six volunteers completed six weeks of progressively increasing intensity stationary cycle cycling. Methods In vastus lateralis muscle biopsies, changes in expression of GLUT1, GLUT4, GLUT5, and GLUT12 were compared using quantitative immunoblots with specific protein standards. Regulatory pathway components were evaluated by immunoblots of muscle homogenates and immunohistochemistry of microscopic sections. Results GLUT1 was unchanged, GLUT4 increased 66%, GLUT12 increased 104%, and GLUT5 decreased 72%. A mitochondrial marker (cytochrome c) and regulators of mitochondrial biogenesis (PGC-1α and phospho-AMPK) were unchanged, but the muscle hypertrophy pathway component, phospho-mTOR increased 83% after the exercise program. In baseline biopsies, GLUT4 by immunohistochemical techniques was 37% greater in Type I (slow twitch, red) muscle fibers, but the exercise training increased GLUT4 expression in Type II (fast twitch, white) fibers by 50%, achieving parity with the Type I fibers. Baseline phospho-mTOR expression was 50% higher in Type II fibers and increased more in Type II fibers (62%) with training, but also increased in Type I fibers (34%). Conclusion Progressive intensity stationary cycle training of previously sedentary subjects increased muscle insulin-responsive glucose transporters (GLUT4 and GLUT12) and decreased the fructose transporter (GLUT5). The increase in GLUT4 occurred primarily in Type II muscle fibers and this coincided with activation of the mTOR muscle hypertrophy pathway. There was little impact on Type I fiber GLUT4 expression and no evidence of change in mitochondrial biogenesis. PMID:20010125

  3. Effect of altering starting length and activation timing of muscle on fiber strain and muscle damage.

    PubMed

    Butterfield, Timothy A; Herzog, Walter

    2006-05-01

    Muscle strain injuries are some of the most frequent injuries in sports and command a great deal of attention in an effort to understand their etiology. These injuries may be the culmination of a series of subcellular events accumulated through repetitive lengthening (eccentric) contractions during exercise, and they may be influenced by a variety of variables including fiber strain magnitude, peak joint torque, and starting muscle length. To assess the influence of these variables on muscle injury magnitude in vivo, we measured fiber dynamics and joint torque production during repeated stretch-shortening cycles in the rabbit tibialis anterior muscle, at short and long muscle lengths, while varying the timing of activation before muscle stretch. We found that a muscle subjected to repeated stretch-shortening cycles of constant muscle-tendon unit excursion exhibits significantly different joint torque and fiber strains when the timing of activation or starting muscle length is changed. In particular, measures of fiber strain and muscle injury were significantly increased by altering activation timing and increasing the starting length of the muscle. However, we observed differential effects on peak joint torque during the cyclic stretch-shortening exercise, as increasing the starting length of the muscle did not increase torque production. We conclude that altering activation timing and muscle length before stretch may influence muscle injury by significantly increasing fiber strain magnitude and that fiber dynamics is a more important variable than muscle-tendon unit dynamics and torque production in influencing the magnitude of muscle injury.

  4. ULTRASTRUCTURE OF BARNACLE GIANT MUSCLE FIBERS

    PubMed Central

    Hoyle, Graham; McNeill, Patricia A.; Selverston, Allen I.

    1973-01-01

    Increasing use of barnacle giant muscle fibers for physiological research has prompted this investigation of their fine structure. The fibers are invaginated by a multibranched system of clefts connecting to the exterior and filled with material similar to that of the basement material of the sarcolemmal complex. Tubules originate from the surface plasma membrane at irregular sites, and also from the clefts They run transversely, spirally, and longitudinally, making many diadic and some triadic contacts with cisternal sacs of the longitudinal sarcoplasmic reticulum. The contacts are not confined to any particular region of the sarcomere. The tubules are wider and their walls are thicker at points of contact with Z material. Some linking of the Z regions occurs across spaces within the fiber which contain large numbers of glycogen particles. A-band lengths are extremely variable, in the range 2.2 µm–20.3 µm (average 5.2 µm) Individual thick filaments have thin (110 Å) hollow regions alternating with thick (340 Å) solid ones. Bridges between thick filaments occur at random points and are not concentrated into an M band The thin:thick filament ratio is variable in different parts of a fiber, from 3:1 to 6:1. Z bands are basically perforated, but the number of perforations may increase during contraction. PMID:4264604

  5. Ablation of Protein Kinase CK2β in Skeletal Muscle Fibers Interferes with Their Oxidative Capacity

    PubMed Central

    Eiber, Nane; Simeone, Luca; Hashemolhosseini, Said

    2017-01-01

    The tetrameric protein kinase CK2 was identified playing a role at neuromuscular junctions by studying CK2β-deficient muscle fibers in mice, and in cultured immortalized C2C12 muscle cells after individual knockdown of CK2α and CK2β subunits. In muscle cells, CK2 activity appeared to be at least required for regular aggregation of nicotinic acetylcholine receptors, which serves as a hallmark for the presence of a postsynaptic apparatus. Here, we set out to determine whether any other feature accompanies CK2β-deficient muscle fibers. Hind limb muscles gastrocnemius, plantaris, and soleus of adult wildtype and CK2β-deficient mice were dissected, cross-sectioned, and stained histochemically by Gomori trichrome and for nicotinamide adenine dinucleotide (NADH) dehydrogenase and succinate dehydrogenase (SDH) enzymatic activities. A reduction of oxidative enzymatic activity was determined for CK2β-deficient muscle fibers in comparison with wildtype controls. Importantly, the CK2β-deficient fibers, muscle fibers that typically exhibit high NADH dehydrogenase and SDH activities, like slow-type fibers, showed a marked reduction in these activities. Altogether, our data indicate additional impairments in the absence of CK2β in skeletal muscle fibers, pointing to an eventual mitochondrial myopathy. PMID:28106831

  6. Automated recognition of the iliac muscle and modeling of muscle fiber direction in torso CT images

    NASA Astrophysics Data System (ADS)

    Kamiya, N.; Zhou, X.; Azuma, K.; Muramatsu, C.; Hara, T.; Fujita, H.

    2016-03-01

    The iliac muscle is an important skeletal muscle related to ambulatory function. The muscles related to ambulatory function are the psoas major and iliac muscles, collectively defined as the iliopsoas muscle. We have proposed an automated recognition method of the iliac muscle. Muscle fibers of the iliac muscle have a characteristic running pattern. Therefore, we used 20 cases from a training database to model the movement of the muscle fibers of the iliac muscle. In the recognition process, the existing position of the iliac muscle was estimated by applying the muscle fiber model. To generate an approximation mask by using a muscle fiber model, a candidate region of the iliac muscle was obtained. Finally, the muscle region was identified by using values from the gray value and boundary information. The experiments were performed by using the 20 cases without abnormalities in the skeletal muscle for modeling. The recognition result in five cases obtained a 76.9% average concordance rate. In the visual evaluation, overextraction of other organs was not observed in 85% of the cases. Therefore, the proposed method is considered to be effective in the recognition of the initial region of the iliac muscle. In the future, we will integrate the recognition method of the psoas major muscle in developing an analytical technique for the iliopsoas area. Furthermore, development of a sophisticated muscle function analysis method is necessary.

  7. Expression profiling reveals heightened apoptosis and supports fiber size economy in the murine muscles of mastication.

    PubMed

    Evans, Marianna; Morine, Kevin; Kulkarni, Cyelee; Barton, Elisabeth R

    2008-09-17

    Distinctions between craniofacial and axial muscles exist from the onset of development and throughout adulthood. The masticatory muscles are a specialized group of craniofacial muscles that retain embryonic fiber properties in the adult, suggesting that the developmental origin of these muscles may govern a pattern of expression that differs from limb muscles. To determine the extent of these differences, expression profiling of total RNA isolated from the masseter and tibialis anterior (TA) muscles of adult female mice was performed, which identified transcriptional changes in unanticipated functional classes of genes in addition to those attributable to fiber type. In particular, the masseters displayed a reduction of transcripts associated with contractile and cytoskeletal load-sensing and anabolic processes, and heightened expression of genes associated with stress. Associated with these observations was a significantly smaller fiber cross-sectional area in masseters, significantly elevated load-sensing signaling (phosphorylated focal adhesion kinase), and increased apoptotic index in masseters compared with TA muscles. Based on these results, we hypothesize that masticatory muscles may have a fundamentally different strategy for muscle design, compared with axial muscles. Specifically there are small diameter fibers that have an attenuated ability to hypertrophy, but an increased propensity to undergo apoptosis. These results may provide insight into the molecular basis for specific muscle-related pathologies associated with masticatory muscles.

  8. Myosin content of individual human muscle fibers isolated by laser capture microdissection

    PubMed Central

    Stone, William L.; Howell, Mary E. A.; Brannon, Marianne F.; Hall, H. Kenton; Gibson, Andrew L.; Stone, Michael H.

    2015-01-01

    Muscle fiber composition correlates with insulin resistance, and exercise training can increase slow-twitch (type I) fibers and, thereby, mitigate diabetes risk. Human skeletal muscle is made up of three distinct fiber types, but muscle contains many more isoforms of myosin heavy and light chains, which are coded by 15 and 11 different genes, respectively. Laser capture microdissection techniques allow assessment of mRNA and protein content in individual fibers. We found that specific human fiber types contain different mixtures of myosin heavy and light chains. Fast-twitch (type IIx) fibers consistently contained myosin heavy chains 1, 2, and 4 and myosin light chain 1. Type I fibers always contained myosin heavy chains 6 and 7 (MYH6 and MYH7) and myosin light chain 3 (MYL3), whereas MYH6, MYH7, and MYL3 were nearly absent from type IIx fibers. In contrast to cardiomyocytes, where MYH6 (also known as α-myosin heavy chain) is seen solely in fast-twitch cells, only slow-twitch fibers of skeletal muscle contained MYH6. Classical fast myosin heavy chains (MHC1, MHC2, and MHC4) were present in variable proportions in all fiber types, but significant MYH6 and MYH7 expression indicated slow-twitch phenotype, and the absence of these two isoforms determined a fast-twitch phenotype. The mixed myosin heavy and light chain content of type IIa fibers was consistent with its role as a transition between fast and slow phenotypes. These new observations suggest that the presence or absence of MYH6 and MYH7 proteins dictates the slow- or fast-twitch phenotype in skeletal muscle. PMID:26676053

  9. Electrical activation of artificial muscles containing polyacrylonitrile gel fibers.

    PubMed

    Schreyer, H B; Gebhart, N; Kim, K J; Shahinpoor, M

    2000-01-01

    Gel fibers made from polyacrylonitrile (PAN) are known to elongate and contract when immersed in caustic and acidic solutions, respectively. The amount of contraction for these pH-activated fibers is 50% or greater, and the strength of these fibers is shown to be comparable to that of human muscle. Despite these attributes, the need of strong acids and bases for actuation has limited the use of PAN gel fibers as linear actuators or artificial muscles. Increasing the conductivity by depositing platinum on the fibers or combining the fibers with graphite fibers has allowed for electrical activation of artificial muscles containing gel fibers when placed in an electrochemical cell. The electrolysis of water in such a cell produces hydrogen ions at an artificial muscle anode, thus locally decreasing the pH and causing the muscle to contract. Reversing the electric field allows the PAN muscle to elongate. A greater than 40% contraction in artificial muscle length in less than 10 min is observed when it is placed as an electrode in a 10 mM NaCl electrolyte solution and connected to a 10 V power supply. These results indicate potential in developing electrically activated PAN muscles and linear actuators, which would be much more applicable than chemically activated muscles.

  10. Influence of exercise and Dianabol on the degradation rate of myofibrillar proteins of the heart and three fiber types of skeletal muscle of female guinea pigs.

    PubMed

    Morano, I

    1984-12-01

    The influence of methandrostenolone (= Dianabol = 17-beta-hydroxy-17-methylandrosta-1,4-dien-3-one) and of a running training program on the degradation rate of myofibrillar proteins of the heart, soleus, red portion of the vastus lateralis, and white portion of the vastus lateralis of female guinea pigs was studied by measuring the time-dependent decrease of radioactive-labeled proteins. The following results were obtained: No alteration of absolute muscle or body weight An increased heart-to-body weight relation in the trained and in the trained group receiving Dianabol A significantly higher myofibrillar protein concentration in the skeletal muscle types than in the heart An increased concentration of myofibrillar proteins in all muscle types in the trained group receiving Dianabol and in the heart of the untrained group receiving Dianabol The degradation rate of the myofibrillar proteins decreased in all muscle types in the trained group receiving Dianabol and in the heart of the untrained group receiving Dianabol and in the trained group.

  11. Is fast fiber innervation responsible for increased acetylcholinesterase activity in reinnervating soleus muscles?

    NASA Technical Reports Server (NTRS)

    Misulis, K. E.; Dettbarn, W. D.

    1985-01-01

    An investigation was conducted as to whether the predominantly slow SOL, which is low in AChE activity, is initially reinnervated by axons that originally innervated fast muscle fibers with high AChE activity, such as those of the EDL. Local denervation of the SOL in the guinea pig was performed because this muscle is composed solely of slow (type I) fibers; thereby virtually eliminating the possibility of homologous muscle fast fiber innervation. The overshoot in this preparation was qualitatively similar to that seen with distal denervation in the guinea pig and local and distal denervation in the rat. Thus, initial fast fiber innvervation is not responsible for the patterns of change in AChE activity seen with reinnervation in the SOL. It is concluded that the neural control of AChe is different in these two muscles and may reflect specific differences in the characteristics of AChE regulation in fast and slow muscle.

  12. Calcium Efflux from Barnacle Muscle Fibers

    PubMed Central

    Russell, J. M.; Blaustein, M. P.

    1974-01-01

    Calcium-45 was injected into single giant barnacle muscle fibers, and the rate of efflux was measured under a variety of conditions. The rate constant (k) for 45Ca efflux into standard seawater averaged 17 x 10–4 min–1 which corresponds to an efflux of about 1–2 pmol/cm2·s. Removal of external Ca (Cao) reduced the efflux by 50%. In most fibers about 40% of the 45Ca efflux into Ca-free seawater was dependent on external Na (Nao); treatment with 3.5 mM caffeine increased the magnitude of the Nao-dependent efflux. In a few fibers removal of Nao, in the absence of Cao, either had no effect or increased k; caffeine (2–3.5 mM) unmasked an Nao-dependent efflux in these fibers. The Nao-dependent Ca efflux had a Q10 of about 3.7. The data are consistent with the idea that a large fraction of the Ca efflux may be carrier-mediated, and may involve both Ca-Ca and Na-Ca counterflow. The relation between the Nao-dependent Ca efflux and the external Na concentration is sigmoid, and suggests that two, or more likely three, external Na+ ions may activate the efflux of one Ca+2. With a three-for-one Na-Ca exchange, the Na electrochemical gradient may be able to supply sufficient energy to maintain the Ca gradient in these fibers. Other, more complex models are not excluded, however, and may be required to explain some puzzling features of the Ca efflux such as the variable Nao-dependence. PMID:4812633

  13. Slow to fast alterations in skeletal muscle fibers caused by clenbuterol, a beta(2)-receptor agonist

    NASA Technical Reports Server (NTRS)

    Zeman, Richard J.; Ludemann, Robert; Easton, Thomas G.; Etlinger, Joseph D.

    1988-01-01

    The effects of a beta(2)-receptor agonist, clenbuterol, and a beta(2) antagonist, butoxamine, on the skeletal muscle fibers of rats were investigated. It was found that chronic treatment of rats with clenbuterol caused hypertrophy of histochemically identified fast-twitch, but not slow-twitch, fibers within the soleus, while in the extensor digitorum longus the mean areas of both fiber types were increased; in both muscles, the ratio of the number of fast-twitch to slow-twitch fibers was increased. In contrast, a treatment with butoxamine caused a reduction of the fast-twitch fiber size in both muscles, and the ratio of the fast-twitch to slow-twitch fibers was decreased.

  14. Muscle organizers in Drosophila: the role of persistent larval fibers in adult flight muscle development

    NASA Technical Reports Server (NTRS)

    Farrell, E. R.; Fernandes, J.; Keshishian, H.

    1996-01-01

    In many organisms muscle formation depends on specialized cells that prefigure the pattern of the musculature and serve as templates for myoblast organization and fusion. These include muscle pioneers in insects and muscle organizing cells in leech. In Drosophila, muscle founder cells have been proposed to play a similar role in organizing larval muscle development during embryogenesis. During metamorphosis in Drosophila, following histolysis of most of the larval musculature, there is a second round of myogenesis that gives rise to the adult muscles. It is not known whether muscle founder cells organize the development of these muscles. However, in the thorax specific larval muscle fibers do not histolyze at the onset of metamorphosis, but instead serve as templates for the formation of a subset of adult muscles, the dorsal longitudinal flight muscles (DLMs). Because these persistent larval muscle fibers appear to be functioning in many respects like muscle founder cells, we investigated whether they were necessary for DLM development by using a microbeam laser to ablate them singly and in combination. We found that, in the absence of the larval muscle fibers, DLMs nonetheless develop. Our results show that the persistent larval muscle fibers are not required to initiate myoblast fusion, to determine DLM identity, to locate the DLMs in the thorax, or to specify the total DLM fiber volume. However, they are required to regulate the number of DLM fibers generated. Thus, while the persistent larval muscle fibers are not obligatory for DLM fiber formation and differentiation, they are necessary to ensure the development of the correct number of fibers.

  15. Mechanisms of nascent fiber formation during avian skeletal muscle hypertrophy

    NASA Technical Reports Server (NTRS)

    McCormick, K. M.; Schultz, E.

    1992-01-01

    This study examined two putative mechanisms of new fiber formation in postnatal skeletal muscle, namely longitudinal fragmentation of existing fibers and de novo formation. The relative contributions of these two mechanisms to fiber formation in hypertrophying anterior latissimus dorsi (ALD) muscle were assessed by quantitative analysis of their nuclear populations. Muscle hypertrophy was induced by wing-weighting for 1 week. All nuclei formed during the weighting period were labeled by continuous infusion of 5-bromo-2'-deoxyuridine (BrdU), a thymidine analog, and embryonic-like fibers were identified using an antibody to ventricular-like embryonic (V-EMB) myosin. The number of BrdU-labeled and unlabeled nuclei in V-EMB-positive fibers were counted. Wing-weighting resulted in significant muscle enlargement and the appearance of many V-EMB+ fibers. The majority of V-EMB+ fibers were completely independent of mature fibers and had a nuclear density characteristics of developing fibers. Furthermore, nearly 100% of the nuclei in independent V-EMB+ fibers were labeled. These findings strongly suggest that most V-EMB+ fibers were nascent fibers formed de novo during the weighting period by satellite cell activation and fusion. Nascent fibers were found primarily in the space between fascicles where they formed a complex anastomosing network of fibers running at angles to one another. Although wing-weighting induced an increase in the number of branched fibers, there was no evidence that V-EMB+ fibers were formed by longitudinal fragmentation. The location of newly formed fibers in wing-weighted and regenerating ALD muscle was compared to determine whether satellite cells in the ALD muscle were unusual in that, if stimulated to divide, they would form fibers in the inter- and intrafascicular space. In contrast to wing-weighted muscle, nascent fibers were always found closely associated with necrotic fibers. These results suggest that wing-weighting is not simply another

  16. Further study of the electrical and machanical responses of slow fibers in cat extraocular muscles.

    PubMed

    Pilar, G

    1967-10-01

    Electrical and mechanical responses have been obtained in situ and in vitro from the superior oblique muscle stimulated by single and repetitive electrical pulses, applied to the trochlear nerve. Two different types of muscle fibers are described, the twitch and the slow. The slow type is characterized electrically by the presence of junctional potentials, which have reversal potentials between -10 and -20 mv, and do not show propagated responses or spikes, during nerve stimulation. When the slow muscle fibers are repetitively stimulated in situ, a prolonged contraction is maintained during stimulation. At the time, the recorded electrical activity is produced locally, at the level of the neuromuscular junctions of the slow fibers. These results indicate that the contractile mechanism of the slow muscle fibers is activated locally and segmentally.

  17. Velocity, force, power, and Ca2+ sensitivity of fast and slow monkey skeletal muscle fibers

    NASA Technical Reports Server (NTRS)

    Fitts, R. H.; Bodine, S. C.; Romatowski, J. G.; Widrick, J. J.

    1998-01-01

    In this study, we determined the contractile properties of single chemically skinned fibers prepared from the medial gastrocnemius (MG) and soleus (Sol) muscles of adult male rhesus monkeys and assessed the effects of the spaceflight living facility known as the experiment support primate facility (ESOP). Muscle biopsies were obtained 4 wk before and immediately after an 18-day ESOP sit, and fiber type was determined by immunohistochemical techniques. The MG slow type I fiber was significantly smaller than the MG type II, Sol type I, and Sol type II fibers. The ESOP sit caused a significant reduction in the diameter of type I and type I/II (hybrid) fibers of Sol and MG type II and hybrid fibers but no shift in fiber type distribution. Single-fiber peak force (mN and kN/m2) was similar between fiber types and was not significantly different from values previously reported for other species. The ESOP sit significantly reduced the force (mN) of Sol type I and MG type II fibers. This decline was entirely explained by the atrophy of these fiber types because the force per cross-sectional area (kN/m2) was not altered. Peak power of Sol and MG fast type II fiber was 5 and 8.5 times that of slow type I fiber, respectively. The ESOP sit reduced peak power by 25 and 18% in Sol type I and MG type II fibers, respectively, and, for the former fiber type, shifted the force-pCa relationship to the right, increasing the Ca2+ activation threshold and the free Ca2+ concentration, eliciting half-maximal activation. The ESOP sit had no effect on the maximal shortening velocity (Vo) of any fiber type. Vo of the hybrid fibers was only slightly higher than that of slow type I fibers. This result supports the hypothesis that in hybrid fibers the slow myosin heavy chain would be expected to have a disproportionately greater influence on Vo.

  18. Effects of chronic centrifugation on skeletal muscle fibers in young developing rats

    NASA Technical Reports Server (NTRS)

    Martin, W. D.

    1980-01-01

    Three groups of 30-d old male and female rats were centrifuged for 2, 4, 8, and 16 weeks, after which their soleus and plantaris muscles were analysed for changes in proportions of muscle fiber types. The groups were: earth control, maintained at earth gravity without rotation; rotation control, subjected to a gravitational force of 1.05 G and 28 rpm; and rotation experimental, subjected to a gravitational force of 2 G and 28 rpm. Muscle fibers were classified into four fiber types on the basis of actomyosin ATPase activity as slow oxidative, fast oxidative glycolytic and either fast glycolytic (plantaris) or intermediate (soleus). Hypergravity resulted in an increase in slow oxidative fibers in soleus relative to the earth control, but not of females treated similarly. The relationship of body weight to the changes in proportion of slow oxidative fibers is discussed.

  19. Fiber-type distribution of the perivertebral musculature in Ambystoma.

    PubMed

    Schilling, Nadja; Deban, Stephen M

    2010-02-01

    Many salamanders locomote in aquatic and terrestrial environments. During swimming, body propulsion is solely produced by the axial musculature generating lateral undulations of the trunk and tail. During terrestrial locomotion, the trunk is oscillated laterally in a standing wave, and body propulsion is achieved by concerted trunk and limb muscle action. The goal of this study was to increase our knowledge of the functional morphology of the tetrapod trunk. We investigated the muscle-fiber-type distribution and the anatomical cross-sectional area of all perivertebral muscles in Ambystoma tigrinum and A. maculatum. Muscle-fiber-type composition was determined in serial cross-sections based on m-ATPase activity. Five different body segments were investigated to test for cranio-caudal changes along the trunk. The overall fiber-type distribution was very similar between the species, but A. tigrinum had relatively larger muscles than A. maculatum, which may be related to its digging behavior. None of the perivertebral muscles possessed a homogeneous fiber-type composition. The M. interspinalis showed a distinct layered organization and may function to ensure the integrity of the spine (local stabilization). The M. dorsalis trunci exhibited the plesiomorphic pattern for notochordates in having a distinct superficial layer of red and intermediate fibers, which covered the central white fibers; therefore, it is suggested to function as a mobilizer and a stabilizer of the trunk, but, may also be involved in modulating body stiffness. Similarly, the M. subvertebralis showed clear regionalizations, implying functional subunits that can stabilize and mobilize the trunk as well as modulate of body stiffness. Cranio-caudally, neither the fiber-type composition nor the a-csa changed dramatically, possibly reflecting the need to perform well in both aquatic and terrestrial habitats.

  20. Anisotropic Smoothing Improves DT-MRI-Based Muscle Fiber Tractography

    PubMed Central

    Buck, Amanda K. W.; Ding, Zhaohua; Elder, Christopher P.; Towse, Theodore F.; Damon, Bruce M.

    2015-01-01

    Purpose To assess the effect of anisotropic smoothing on fiber tracking measures, including pennation angle, fiber tract length, and fiber tract number in the medial gastrocnemius (MG) muscle in healthy subjects using diffusion-weighted magnetic resonance imaging (DW-MRI). Materials and Methods 3T DW-MRI data were used for muscle fiber tractography in the MG of healthy subjects. Anisotropic smoothing was applied at three levels (5%, 10%, 15%), and pennation angle, tract length, fiber tract number, fractional anisotropy, and principal eigenvector orientation were quantified for each smoothing level. Results Fiber tract length increased with pre-fiber tracking smoothing, and local heterogeneities in fiber direction were reduced. However, pennation angle was not affected by smoothing. Conclusion Modest anisotropic smoothing (10%) improved fiber-tracking results, while preserving structural features. PMID:26010830

  1. Spaceflight effects on single skeletal muscle fiber function in the rhesus monkey

    NASA Technical Reports Server (NTRS)

    Fitts, R. H.; Desplanches, D.; Romatowski, J. G.; Widrick, J. J.

    2000-01-01

    The purpose of this investigation was to understand how 14 days of weightlessness alters the cellular properties of individual slow- and fast-twitch muscle fibers in the rhesus monkey. The diameter of the soleus (Sol) type I, medial gastrocnemius (MG) type I, and MG type II fibers from the vivarium controls averaged 60 +/- 1, 46 +/- 2, and 59 +/- 2 microm, respectively. Both a control 1-G capsule sit (CS) and spaceflight (SF) significantly reduced the Sol type I fiber diameter (20 and 13%, respectively) and peak force, with the latter declining from 0.48 +/- 0.01 to 0.31 +/- 0.02 (CS group) and 0.32 +/- 0.01 mN (SF group). When the peak force was expressed as kiloNewtons per square meter (kN/m(2)), only the SF group showed a significant decline. This group also showed a significant 15% drop in peak fiber stiffness that suggests that fewer cross bridges were contracting in parallel. In the MG, SF but not CS depressed the type I fiber diameter and force. Additionally, SF significantly depressed absolute (mN) and relative (kN/m(2)) force in the fast-twitch MG fibers by 30% and 28%, respectively. The Ca(2+) sensitivity of the type I fiber (Sol and MG) was significantly reduced by growth but unaltered by SF. Flight had no significant effect on the mean maximal fiber shortening velocity in any fiber type or muscle. The post-SF Sol type I fibers showed a reduced peak power and, at peak power, an elevated velocity and decreased force. In conclusion, CS and SF caused atrophy and a reduced force and power in the Sol type I fiber. However, only SF elicited atrophy and reduced force (mN) in the MG type I fiber and a decline in relative force (kN/m(2)) in the Sol type I and MG type II fibers.

  2. Metabolic and morphologic properties of single muscle fibers in the rat after spaceflight, Cosmos 1887

    NASA Technical Reports Server (NTRS)

    Miu, B.; Martin, T. P.; Roy, R. R.; Oganov, V.; Ilyina-Kakueva, E.; Marini, J. F.; Leger, J. J.; Bodine-Fowler, S. C.; Edgerton, V. R.

    1990-01-01

    The adaptation of a slow (soleus, Sol) and a fast (medial gastrocnemius, MG) skeletal muscle to spaceflight was studied in five young male rats. The flight period was 12.5 days and the rats were killed approximately 48 h after returning to 1 g. Five other rats that were housed in cages similar to those used by the flight rats were maintained at 1 g for the same period of time to serve as ground-based controls. Fibers were classified as dark or light staining for myosin adenosine triphosphatase (ATPase). On the average, the fibers in the Sol of the flight rats atrophied twice as much as those in the MG. Further, the fibers located in the deep (close to the bone and having the highest percentage of light ATPase and high oxidative fibers in the muscle cross section) region of the MG atrophied more than the fibers located in the superficial (away from the bone and having the lowest percentage of light ATPase and high oxidative fibers in the muscle cross-section) region of the muscle. Based on quantitative histochemical assays of single muscle fibers, succinate dehydrogenase (SDH) activity per unit volume was unchanged in fibers of the Sol and MG. However, in the Sol, but not the MG, the total amount of SDH activity in a 10-microns-thick section of a fiber decreased significantly in response to spaceflight. Based on population distributions, it appears that the alpha-glycerophosphate dehydrogenase (GPD) activities were elevated in the dark ATPase fibers in the Sol, whereas the light fibers in the Sol and both fiber types in the MG did not appear to change. The ratio of GPD to SDH activities increased in the dark (but not light) fibers of the Sol and was unaffected in the MG. Immunohistochemical analyses indicate that approximately 40% of the fibers in the Sol of flight rats expressed a fast myosin heavy chain compared with 22% in control rats. Further, 31% of the fibers in the Sol of flight rats expressed both fast and slow myosin heavy chains compared with 8% in

  3. Slow fiber cluster pattern in pig longissimus thoracis muscle: implications for myogenesis.

    PubMed

    Fonseca, S; Wilsons, I J; Horgan, G W; Maltin, C A

    2003-04-01

    Recent evidence implicates fiber type proportions as playing a role in meat eating quality, and in pigs it has been suggested that the slow oxidative fibers contribute to both juiciness and tenderness. The fiber distribution in pigs is different from that found in most other species, in which the various types of skeletal muscle fiber are distributed in a "checkerboard" pattern, because in pigs the slow oxidative fibers have a clustered distribution. The initial processes leading to fiber clustering are likely to occur during myogenesis, but the precise mechanistic aetiology of this patterning and whether the slow oxidative fiber clusters occur in a random or ordered fashion is unknown. In the present study longissimus thoracis muscle from Large White crossbred pigs was sampled at the 10th rib, 48 h postmortem. Transverse cryo-sections were cut and histochemically stained to allow the identification of the main muscle fiber types: slow oxidative, fast glycolytic, and fast oxidative glycolytic. Images of the sections were captured and analyzed using point processes and Voronoi Tesselations to examine the randomness and spatial distribution of the clusters of slow oxidative fibers found in pig longissimus thoracis muscle. The results showed that an assumption of complete spatial randomness can be rejected and that a mathematical model incorporating a minimum distance of 1.7 to 2.0 microm between cluster centers produced fiber patterns similar to those observed in the original transverse sections of the muscle. In addition, if it assumed that the central fiber in each cluster is derived from primary myoblast progenitors, these results suggest that there may be some degree of repulsion between the primary fibers during the initial stages of cluster formation. The mechanistic basis of such repulsion is not clear, but it is speculated that secreted factors, such as sonic hedgehog or myostatin may play a role.

  4. Denervation produces different single fiber phenotypes in fast- and slow-twitch hindlimb muscles of the rat.

    PubMed

    Patterson, M F; Stephenson, G M M; Stephenson, D G

    2006-09-01

    Using a single, mechanically skinned fiber approach, we tested the hypothesis that denervation (0 to 50 days) of skeletal muscles that do not overlap in fiber type composition [extensor digitorum longus (EDL) and soleus (SOL) muscles of Long-Evans hooded rats] leads to development of different fiber phenotypes. Denervation (50 day) was accompanied by 1) a marked increase in the proportion of hybrid IIB/D fibers (EDL) and I/IIA fibers (SOL) from 30% to >75% in both muscles, and a corresponding decrease in the proportion of pure fibers expressing only one myosin heavy chain (MHC) isoform; 2) complex muscle- and fiber-type specific changes in sarcoplasmic reticulum Ca(2+)-loading level at physiological pCa approximately 7.1, with EDL fibers displaying more consistent changes than SOL fibers; 3) decrease by approximately 50% in specific force of all fiber types; 4) decrease in sensitivity to Ca(2+), particularly for SOL fibers (by approximately 40%); 5) decrease in the maximum steepness of the force-pCa curves, particularly for the hybrid I/IIA SOL fibers (by approximately 35%); and 6) increased occurrence of biphasic behavior with respect to Sr(2+) activation in SOL fibers, indicating the presence of both slow and fast troponin C isoforms. No fiber types common to the two muscles were detected at any time points (day 7, 21, and 50) after denervation. The results provide strong evidence that not only neural factors, but also the intrinsic properties of a muscle fiber, influence the structural and functional properties of a particular muscle cell and explain important functional changes induced by denervation at both whole muscle and single cell levels.

  5. Chronic treatment with 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside increases insulin-stimulated glucose uptake and GLUT4 translocation in rat skeletal muscles in a fiber type-specific manner.

    PubMed

    Buhl, E S; Jessen, N; Schmitz, O; Pedersen, S B; Pedersen, O; Holman, G D; Lund, S

    2001-01-01

    Recent studies have demonstrated that chronic administration of AICAR (5-aminoimidazole-4-carboxamide- 1-beta-D-ribofuranoside), an activator of the AMP-activated protein kinase, increases hexokinase activity and the contents of total GLUT4 and glycogen in rat skeletal muscles. To explore whether AICAR also affects insulin-stimulated glucose transport and GLUT4 cell surface content, Wistar rats were subcutaneously injected with AICAR for 5 days in succession (1 mg/g body wt). Maximally insulin-stimulated (60 nmol/l) glucose uptake was markedly increased in epitrochlearis (EPI) muscle (average 63%, P < 0.001, n = 18-19) and in extensor digitorum longus muscle (average 26%, P < 0.001, n = 26-30). In contrast, administration of AICAR did not maximally influence insulin-stimulated glucose transport in soleus muscle. Studies of EPI muscle with the 4,4'-O-[2-[2-[2-[2-[2-[6-(biotinylamino)hexanoyl]amino]ethoxy]ethoxy] ethoxy]-4-(1-azi-2,2,2,-trifluoroethyl)benzoyl]amino-1,3-propanediyl]bis-D-mannose photolabeling technique showed a concomitant increase (average 68%, P < 0.02) in cell surface GLUT4 content after insulin exposure in AICAR-injected rats when compared with controls. In conclusion, 5 days of AICAR administration induces a pronounced fiber type-specific increase in insulin-stimulated glucose uptake and GLUT4 cell surface content in rat skeletal muscle with the greatest effect observed on white fast-twitch glycolytic muscles (EPI). These results are comparable with the effects of chronic exercise training, and it brings the AMP-activated protein kinase into focus as a new interesting target for future pharmacological intervention in insulin-resistant conditions.

  6. Size and myonuclear domains in Rhesus soleus muscle fibers: short-term spaceflight

    NASA Technical Reports Server (NTRS)

    Roy, R. R.; Zhong, H.; Talmadge, R. J.; Bodine, S. C.; Fanton, J. W.; Koslovskaya, I.; Edgerton, V. R.

    2001-01-01

    The cross-sectional area (CSA), myonuclear number per mm of fiber length, and myonuclear domain (cytoplasmic volume/myonucleus) of mechanically isolated single fibers from biopsies of the soleus muscle of 5 vivarium control, 3 flight simulation and 2 flight (BION 11) Rhesus monkeys (Macaca [correction of Macacca] mulatta) were determined using confocal microscopy before and after a 14-day experimental period. Simulation monkeys were confined in chairs placed in capsules identical to those used during the flight. Fibers were classified as type I, type II or hybrid (containing both types I and II) based on myosin heavy chain (MHC) gel electrophoresis. A majority of the fibers sampled contained only type I MHC, i.e. 89, 62 and 68% for the control, simulation and flight groups, respectively. Most of the remaining fibers were hybrids, i.e. 8, 36 and 32% for the same groups. There were no significant pre-post differences in the fiber type composition for any of the experimental groups. There also were no significant pre-post differences in fiber CSA, myonuclear number or myonuclear domain. There was, however, a tendency for the fibers in the post-flight biopsies to have a smaller mean CSA and myonuclear domain (approximately 10%, p=0.07) than the fibers in the pre-flight biopsy. The combined mean cytoplasmic volume/myonucleus for all muscle fiber phenotypes in the Rhesus soleus muscle was approximately 25,000 micrometers3 and there were no differences in pre-post samples for the control and simulated groups. The cytoplasmic domains tended to be lower (p=0.08) after than before flight. No phenotype differences in cytoplasmic domains were observed. These data suggest that after a relatively short period of actual spaceflight, modest fiber atrophy occurs in the soleus muscle fibers without a concomitant change in myonuclear number.

  7. Immunohistochemical detection of interleukin-6 in human skeletal muscle fibers following exercise.

    PubMed

    Penkowa, Milena; Keller, Charlotte; Keller, Pernille; Jauffred, Sune; Pedersen, Bente Klarlund

    2003-11-01

    Interleukin-6 (IL-6) is produced by many different cell types. Human skeletal muscles produce and release high amounts of IL-6 during exercise; however, the cell source of origin in the muscle is not known. Therefore, we studied the protein expression of IL-6 by immunohistochemistry in human muscle tissue from biopsies obtained at time points 0, 3, 4.5, 6, 9, and 24 h in relation to 3 h of bicycle exercise performed by healthy young males (n=12) and in resting controls (n=6). The IL-6 expression was clearly increased after exercise and remained high even by 24 h, relative to pre-exercise or resting individuals. The IL-6 immunostainings of skeletal muscle cells were homogeneous and without difference between muscle fiber types. The IL-6 mRNA peaked immediately after the exercise, and, in accordance, the IL-6 protein expression within muscle cells was most pronounced around 3 h post-exercise. However, the finding that plasma IL-6 concentration peaked in the end of exercise indicates a high turnover of muscle-derived IL-6. In conclusion, the finding of marked IL-6 protein expression exclusively within skeletal muscle fibers following exercise demonstrates that skeletal muscle fibers of all types are the dominant cell source of exercise-induced release of IL-6 from working muscle.

  8. Effective fiber hypertrophy in satellite cell-depleted skeletal muscle.

    PubMed

    McCarthy, John J; Mula, Jyothi; Miyazaki, Mitsunori; Erfani, Rod; Garrison, Kelcye; Farooqui, Amreen B; Srikuea, Ratchakrit; Lawson, Benjamin A; Grimes, Barry; Keller, Charles; Van Zant, Gary; Campbell, Kenneth S; Esser, Karyn A; Dupont-Versteegden, Esther E; Peterson, Charlotte A

    2011-09-01

    An important unresolved question in skeletal muscle plasticity is whether satellite cells are necessary for muscle fiber hypertrophy. To address this issue, a novel mouse strain (Pax7-DTA) was created which enabled the conditional ablation of >90% of satellite cells in mature skeletal muscle following tamoxifen administration. To test the hypothesis that satellite cells are necessary for skeletal muscle hypertrophy, the plantaris muscle of adult Pax7-DTA mice was subjected to mechanical overload by surgical removal of the synergist muscle. Following two weeks of overload, satellite cell-depleted muscle showed the same increases in muscle mass (approximately twofold) and fiber cross-sectional area with hypertrophy as observed in the vehicle-treated group. The typical increase in myonuclei with hypertrophy was absent in satellite cell-depleted fibers, resulting in expansion of the myonuclear domain. Consistent with lack of nuclear addition to enlarged fibers, long-term BrdU labeling showed a significant reduction in the number of BrdU-positive myonuclei in satellite cell-depleted muscle compared with vehicle-treated muscle. Single fiber functional analyses showed no difference in specific force, Ca(2+) sensitivity, rate of cross-bridge cycling and cooperativity between hypertrophied fibers from vehicle and tamoxifen-treated groups. Although a small component of the hypertrophic response, both fiber hyperplasia and regeneration were significantly blunted following satellite cell depletion, indicating a distinct requirement for satellite cells during these processes. These results provide convincing evidence that skeletal muscle fibers are capable of mounting a robust hypertrophic response to mechanical overload that is not dependent on satellite cells.

  9. Muscle Degeneration in Neuramindase 1 Deficient Mice Results from Infiltration of the Muscle Fibers by Expanded Connective Tissue

    PubMed Central

    Zanoteli, Edmar; van de Vlekkert, Diantha; Bonten, Erik J.; Hu, Huimin; Mann, Linda; Gomero, Elida M.; Harris, A. John; Ghersi, Giulio; d’Azzo, Alessandra

    2010-01-01

    SUMMARY Neuraminidase 1 (NEU1) regulates the catabolism of sialoglycoconjugates in lysosomes. Congenital NEU1 deficiency in children is the basis of sialidosis, a severe neurosomatic disorder in which patients experience a broad spectrum of clinical manifestations varying in the age of onset and severity. Osteoskeletal deformities and muscle hypotonia have been described in patients with sialidosis. Here we present the first comprehensive analysis of the skeletal muscle pathology associated with loss of Neu1 function in mice. In this animal model, skeletal muscles showed an expansion of the epimysial and perimysial spaces, associated with proliferation of fibroblast-like cells and abnormal deposition of collagens. Muscle fibers located adjacent to the expanded connective tissue underwent extensive invagination of their sarcolemma, which resulted in the infiltration of the fibers by fibroblast-like cells and extracellular matrix, and in their progressive cytosolic fragmentation. Both the expanded connective tissue and the juxtaposed infiltrated muscle fibers were strongly positive for lysosomal markers, and displayed increased proteolytic activity of lysosomal cathepsins and metalloproteinases. These combined features could lead to abnormal remodeling of the extracellular matrix that could be responsible for sarcolemmal invagination and progressive muscle fiber degeneration, ultimately resulting in an overt atrophic phenotype. This unique pattern of muscle damage, which has never been described in any myopathy, might explain the neuromuscular manifestations reported in patients with the type II severe form of sialidosis. More broadly, these findings point to a potential role of NEU1 in cell proliferation and extracellular matrix remodeling. PMID:20388541

  10. Gravitational unloading effects on muscle fiber size, phenotype and myonuclear number

    NASA Technical Reports Server (NTRS)

    Ohira, Y.; Yoshinaga, T.; Nomura, T.; Kawano, F.; Ishihara, A.; Nonaka, I.; Roy, R. R.; Edgerton, V. R.

    2002-01-01

    The effects of gravitational unloading with or without intact neural activity and/or tension development on myosin heavy chain (MHC) composition, cross-sectional area (CSA), number of myonuclei, and myonuclear domain (cytoplasmic volume per myonucleus ratio) in single fibers of both slow and fast muscles of rat hindlimbs are reviewed briefly. The atrophic response to unloading is generally graded as follows: slow extensors > fast extensors > fast flexors. Reduction of CSA is usually greater in the most predominant fiber type of that muscle. The percentage of fibers expressing fast MHC isoforms increases in unloaded slow but not fast muscles. Myonuclear number per mm of fiber length and myonuclear domain is decreased in the fibers of the unloaded predominantly slow soleus muscle, but not in the predominantly fast plantaris. Decreases in myonuclear number and domain, however, are observed in plantaris fibers when tenotomy, denervation, or both are combined with hindlimb unloading. All of these results are consistent with the view that a major factor for fiber atrophy is an inhibition or reduction of loading of the hindlimbs. These data also indicate that predominantly slow muscles are more responsive to unloading than predominantly fast muscles. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

  11. High endocytotic activity occurs periodically in the endplate region of denervated mouse striated muscle fibers.

    PubMed

    Lawoko, G; Tågerud, S

    1995-08-01

    High endocytotic activity after denervation of skeletal muscle occurs in a proportion of muscle fibers (both slow and fast fiber types) in the endplate region. The present study was performed in order to examine if a periodicity in the endocytotic activity could explain why the process is not observed in all fibers at a given time. Three markers, horseradish peroxidase (HRP), rhodamine B isothiocyanate-labeled dextran, and fluorescein isothiocyanate-labeled dextran were used to demonstrate endocytotic activity of muscle fibers of the denervated mouse hemidiaphragm in vivo. Acetylcholine esterase staining was used in conjunction with HRP uptake to determine the proportion of denervated muscle fibers with endocytotic activity in the endplate region at any one time. The results show that 25-50% of the muscle fibers display high endocytotic activity in the endplate region at a given time 10 days after denervation. The existence of a periodicity in this endocytotic activity is suggested by results obtained using two different endocytotic markers administered at time intervals of 0-7 days. We conclude that loss of contact with the innervating motorneuron induces a high endocytotic activity which occurs periodically in the perisynaptic region of skeletal muscle fibers.

  12. Mitochondrial specialization revealed by single muscle fiber proteomics: focus on the Krebs cycle.

    PubMed

    Schiaffino, S; Reggiani, C; Kostrominova, T Y; Mann, M; Murgia, M

    2015-12-01

    We have developed a highly sensitive mass spectrometry-based proteomic workflow to examine the proteome of single muscle fibers. This study revealed significant differences in the mitochondrial proteome of the four major fiber types present in mouse skeletal muscle. Here, we focus on Krebs cycle enzymes and in particular on the differential distribution of the two mitochondrial isocitrate dehydrogenases, IDH2 and IDH3. Type 1/slow fibers contain high levels of IDH2 and relatively low levels of IDH3, whereas fast 2X and 2B fibers show an opposite expression pattern. The findings suggest that in skeletal muscle, IDH2 functions in the forward direction of the Krebs cycle and that substrate flux along the cycle occurs predominantly via IDH2 in type 1 fibers and via IDH3 in 2X and 2B fibers. IDH2-mediated conversion of isocitrate to α-ketoglutarate leads to the generation of NADPH, which is critical to buffering the H2O2 produced by the respiratory chain. Nicotinamide nucleotide transhydrogenase (NNT), the other major mitochondrial enzyme involved in NADPH generation, is also more abundant in type 1 fibers. We suggest that the continuously active type 1 fibers are endowed with a more efficient H2O2 scavenging capacity to cope with the higher levels of reactive oxygen species production.

  13. Fiber polymorphism in skeletal muscles of the American lobster, Homarus americanus: continuum between slow-twitch (S1) and slow-tonic (S2) fibers.

    PubMed

    Medler, Scott; Lilley, Travis; Mykles, Donald L

    2004-07-01

    In recent years, an increasing number of studies has reported the existence of single fibers expressing more than one myosin heavy chain (MHC) isoform at the level of fiber proteins and/or mRNA. These mixed phenotype fibers, often termed hybrid fibers, are currently being recognized as the predominant fiber type in many muscles, and the implications of these findings are currently a topic of great interest. In a recent study, we reported single fibers from the cutter claw closer muscle of lobsters that demonstrated a gradation between the slow-twitch (S1) and slow-tonic (S2) muscle phenotype. In the present study, we focused on S1 and S2 fibers from the superficial abdominal muscles of the lobster as a model to study the continuum among muscle fiber types. Complementary DNAs (cDNA) encoding an S2 isoform of myosin heavy chain (MHC) and an S2 isoform of tropomyosin (Tm) were isolated from the superficial abdominal flexor muscles of adult lobsters. These identified sequences were used to design PCR primers used in conjunction with RT-PCR and real-time PCR to measure expression levels of these genes in small muscle samples and single fibers. The relative expression of the corresponding S1 MHC and S1 Tm isoforms was measured in the same samples with PCR primers designed according to previously identified sequences. In addition, we measured the relative proportions of MHC, troponin (Tn) T and I protein isoforms present in the same samples to examine the correlation of these proteins with one another and with the MHC and Tm mRNAs. These analyses revealed significant correlations among the different myofibrillar proteins, with the S1 and S2 fibers being characterized by a whole assemblage of myofibrillar isoforms. However, they also showed that small muscle samples, and more importantly single fibers, existed as a continuum from one phenotype to another. Most fibers possessed mixtures of mRNA for MHC isoforms that were unexpected based on protein analysis. These findings

  14. Creatine Supplementation Induces Alteration in Cross-Sectional Area in Skeletal Muscle Fibers of Wistar Rats Under Swimming Training

    PubMed Central

    Santos, Fernando Farias Dos; Moura, José A. A.; Curi, Rui; Fernandes, Luiz C.

    2002-01-01

    Creatine has been shown to increase the total muscle mass. In this study, we investigated the effect of oral creatine monohydrate supplementation on cross-sectional area of type I, IIA and IIB fibers of gastrocnemius, extensor digitorum longus - EDL and soleus muscles from male Wistar rats subjected to swimming training for 33 days. Four groups were set up: sedentary with no supplementation (CON), sedentary with creatine supplementation (3.3 mg creatine per g chow) (CR), exercised with no supplementation (EX) and exercised with supplementation (CREX). The rats performed in a special swimming pool and swam five times a week for 1 hour each day, with a extra lead weight corresponding to 15% of their body weight. At the end of 33 days, skeletal muscles of the animals were dissected and the samples got immediately frozen using liquid nitrogen. Muscle samples were allocated to slices of 10 μm by a cryostat at -20°C, which was followed by histochemical analysis in order to identify fiber types of the muscles, and morphometrical analysis to calculate the muscle fiber areas. All groups gained body weight at the end of 33 days but there was no statistical difference among them. The EX and CREX rats had a larger food intake than the sedentary groups (CON and CR), and the CREX group had a larger food intake than CR rats. The cross-sectional area of type I and IIA fibers of the soleus muscle, type IIA and IIB fibers of EDL muscle and type IIA and IIB fibers of the white portion of gastrocnemius muscle were greater in the EX and CREX groups in comparison to sedentary rats. In addition, these fibers were greater in the CREX rats than in the EX group. There was no change in the cross sectional area of type I fibers in EDL muscle among all groups studied. Our results suggest that creatine supplementation enhances the exercise related muscle fiber hypertrophy in rodents. PMID:24701129

  15. Changes in muscle fiber contractility and extracellular matrix production during skeletal muscle hypertrophy.

    PubMed

    Mendias, Christopher L; Schwartz, Andrew J; Grekin, Jeremy A; Gumucio, Jonathan P; Sugg, Kristoffer B

    2017-03-01

    Skeletal muscle can adapt to increased mechanical loads by undergoing hypertrophy. Transient reductions in whole muscle force production have been reported during the onset of hypertrophy, but contractile changes in individual muscle fibers have not been previously studied. Additionally, the extracellular matrix (ECM) stores and transmits forces from muscle fibers to tendons and bones, and determining how the ECM changes during hypertrophy is important in understanding the adaptation of muscle tissue to mechanical loading. Using the synergist ablation model, we sought to measure changes in muscle fiber contractility, collagen content, and cross-linking, and in the expression of several genes and activation of signaling proteins that regulate critical components of myogenesis and ECM synthesis and remodeling during muscle hypertrophy. Tissues were harvested 3, 7, and 28 days after induction of hypertrophy, and nonoverloaded rats served as controls. Muscle fiber specific force (sFo), which is the maximum isometric force normalized to cross-sectional area, was reduced 3 and 7 days after the onset of mechanical overload, but returned to control levels by 28 days. Collagen abundance displayed a similar pattern of change. Nearly a quarter of the transcriptome changed over the course of overload, as well as the activation of signaling pathways related to hypertrophy and atrophy. Overall, this study provides insight into fundamental mechanisms of muscle and ECM growth, and indicates that although muscle fibers appear to have completed remodeling and regeneration 1 mo after synergist ablation, the ECM continues to be actively remodeling at this time point.NEW & NOTEWORTHY This study utilized a rat synergist ablation model to integrate changes in single muscle fiber contractility, extracellular matrix composition, activation of important signaling pathways in muscle adaption, and corresponding changes in the muscle transcriptome to provide novel insight into the basic

  16. Individual sarcomere lengths in whole muscle fibers and optimal fiber length computation.

    PubMed

    Infantolino, Benjamin W; Ellis, Michael J; Challis, John H

    2010-11-01

    Estimation of muscle fiber optimum length is typically accomplished using either laser diffraction or by counting the number of sarcomeres in a portion of the muscle fiber, measuring the distance that encompasses those sarcomeres and dividing by the number of sarcomeres to obtain an average sarcomere length. If the sarcomeres are not uniformly distributed, either of these techniques could produce errors when estimating optimum lengths. The purposes of this study were: to describe new software that automatically analyzes digital images of skeletal muscle fibers to measure individual sarcomere lengths; and to use this software to measure individual sarcomere lengths along complete muscle fibers to examine the influence of computing whole muscle fiber properties from portions of the fiber. Six complete muscle fibers were imaged using a digital camera attached to a microscope. The images were then processed to achieve the best resolution possible, individual sarcomeres along the image were detected, and each individual sarcomere length was measured. The software accuracy was compared with that of manual measurement and was found to be as accurate. In addition, the time to measure individual sarcomere lengths was greatly reduced using the software compared with manual measurement. The arrangement of individual sarcomere lengths demonstrated long-range correlations, which indicates problems in assuming only a portion of a fiber can be used to determine whole fiber properties. This study has provided evidence on the number of sarcomeres which must be analyzed to infer the properties of whole muscles.

  17. Ultrastructural study of muscles fibers in tick Hyalomma (Hyalomma) anatolicum anatolicum (Ixodoidea: Ixodidae).

    PubMed

    Bughdadi, Faisal A

    2010-09-01

    In the present study, ticks were obtained from a colony maintained at 28 degrees C and 75% relative humidity in at the Department of Biology, University College Umm Al-Qura University, Saudi Arabia and the Transmission Electron Microscope technique (TEM) was used to describes the ultrastructure and description of muscle of the of ixodid tick Hyalomma (Hyalomma) anatolicum anatolicum. The results showed that muscles of the unfed ticks Hyalomma (Hyalomma) anatolicum anatolicum in longitudinal sections are spindle-shaped to cylindrical muscle fibers. In the unfed nymph Hyalomma (Hyalomma) anatolicum anatolicum skeletal and visceral muscles are distinguished according to structure, function and position. These muscles include the capitulum, dorsoventral and leg oblique muscles. All muscle fibers are ensheathed (covered by sheath) in a sarcolemma. Their muscle fibers have striated pattern of successive sarcomeres whose thick myosin filaments are surrounded by orbitals of up to 12 thin actin filaments. The cytoplasm of the epidermal cell appears largely devoted with complicated microtubules present in parallel with long axis of adjacent muscle fibers. The cell membrane invaginates into tubular system extending deeply into the sarcoplasm and closely associated to cisternae of sarcoplasmic reticulum. The tubular system and sarcoplasmic reticulum forming two-membered (dyads) are considered to be the main route of calcium ions whose movement are synchronized with the motor impulse to control muscles contraction. In the sarcoplasm two types of muscle fibers are recognized according to thickness and density and mitochondrial size, distribution and population. Both skeletal and visceral muscles are invaginated by tracheoles and innervated by nerve axons containing synaptic vesicles. The actin and myosin filaments are slightly interrupted and the tubular system sarcoplasmic reticulum is well demonstrated.

  18. Maximal sprint speeds and muscle fiber composition of wild and laboratory house mice.

    PubMed

    Garland, T; Gleeson, T T; Aronovitz, B A; Richardson, C S; Dohm, M R

    1995-11-01

    We compared males from four groups of house mice (Mus domesticus), all bred and raised under common conditions in the laboratory: randombred Hsd:ICR; a wild population from Wisconsin; hybrids from lab dams; hybrids from wild dams. Wild mice were much faster sprinters (maximal forced sprint speeds over 1.0 m ranged from 2.38 to 3.34 m/s) than were lab mice (range = 0.89-1.68 m/s). Hybrids exhibited intermediate speeds (range = 1.54-2.70 m/s) and body masses, indicating largely additive inheritance. Type-specific mean muscle fiber cross-sectional areas of the gastrocnemius muscle did not differ significantly among groups. Percentage cross-sectional areas occupied by each of the three identified fiber types also did not differ significantly among groups, nor did they covary with body mass. For their body mass, however, lab mice had smaller gastrocnemius muscles than did wild and hybrid mice, which had muscles of similar size. Although we cannot rule out the possibility that smaller gastrocnemius muscles or slight differences in fiber composition account for the lower sprint speeds of the lab mice, we suggest that differences in unmeasured physiological, behavioral or motivational factors are probably the primary cause. This interpretation is supported by a lack of correlation between individual differences in sprint speed and either relative gastrocnemius muscle mass or muscle fiber type composition.

  19. Fiber size and myosin phenotypes of selected rhesus lower limb muscles after a 14-day spaceflight

    NASA Technical Reports Server (NTRS)

    Roy, R. R.; Zhong, H.; Bodine, S. C.; Pierotti, D. J.; Talmadge, R. J.; Barkhoudarian, G.; Kim, J.; Fanton, J. W.; Kozlovskaya, I. B.; Edgerton, V. R.

    2000-01-01

    Muscle biopsies were taken from the rhesus (Macaca mulatta) soleus (Sol, a slow ankle extensor), medial gastrocnemius (MG, a fast ankle extensor), tibialis anterior (TA, a fast ankle flexor), and vastus lateralis (VL, a fast knee extensor) muscles in vivarium controls (n=5) before and after either a 14-day spaceflight (Bion 11, n=2) or a 14-day ground-based flight simulation (n=3). Myosin heavy chain (MHC) composition (gel electrophoresis), fiber type distribution (immunohistochemistry), and fiber size were determined. Although there were no significant changes, each muscle showed trends towards adaptation.

  20. Contractile properties of muscle fibers from the deep and superficial digital flexors of horses.

    PubMed

    Butcher, M T; Chase, P B; Hermanson, J W; Clark, A N; Brunet, N M; Bertram, J E A

    2010-10-01

    Equine digital flexor muscles have independent tendons but a nearly identical mechanical relationship to the main joint they act upon. Yet these muscles have remarkable diversity in architecture, ranging from long, unipennate fibers ("short" compartment of DDF) to very short, multipennate fibers (SDF). To investigate the functional relevance of the form of the digital flexor muscles, fiber contractile properties were analyzed in the context of architecture differences and in vivo function during locomotion. Myosin heavy chain (MHC) isoform fiber type was studied, and in vitro motility assays were used to measure actin filament sliding velocity (V(f)). Skinned fiber contractile properties [isometric tension (P(0)/CSA), velocity of unloaded shortening (V(US)), and force-Ca(2+) relationships] at both 10 and 30°C were characterized. Contractile properties were correlated with MHC isoform and their respective V(f). The DDF contained a higher percentage of MHC-2A fibers with myosin (heavy meromyosin) and V(f) that was twofold faster than SDF. At 30°C, P(0)/CSA was higher for DDF (103.5 ± 8.75 mN/mm(2)) than SDF fibers (81.8 ± 7.71 mN/mm(2)). Similarly, V(US) (pCa 5, 30°C) was faster for DDF (2.43 ± 0.53 FL/s) than SDF fibers (1.20 ± 0.22 FL/s). Active isometric tension increased with increasing Ca(2+) concentration, with maximal Ca(2+) activation at pCa 5 at each temperature in fibers from each muscle. In general, the collective properties of DDF and SDF were consistent with fiber MHC isoform composition, muscle architecture, and the respective functional roles of the two muscles in locomotion.

  1. Ultrastructural alterations in skeletal muscle fibers of rats after exercise

    NASA Technical Reports Server (NTRS)

    Akuzawa, M.; Hataya, M.

    1982-01-01

    Ultrastructural alterations in skeletal muscle fibers were electron microscopically studied in rats forced to run on the treadmill until all-out. When they were mild and limited to relatively small areas, the reconstruction of filaments ensued within 10 days without infiltration of cells. When they were severe and extensive, phagocytes infiltrated in the lesions and removed degenerative sacroplasmic debris from muscle fibers. A little later, myoblasts appeared and regeneration was accomplished in 30 days in much the same manner as in myogenesis.

  2. From Slow to Fast: Hypogravity-Induced Remodeling of Muscle Fiber Myosin Phenotype

    PubMed Central

    Shenkman, B. S.

    2016-01-01

    Skeletal muscle consists of different fiber types arranged in a mosaic pattern. These fiber types are characterized by specific functional properties. Slow-type fibers demonstrate a high level of fatigue resistance and prolonged contraction duration, but decreased maximum contraction force and velocity. Fast-type fibers demonstrate high contraction force and velocity, but profound fatigability. During the last decades, it has been discovered that all these properties are determined by the predominance of slow or fast myosin-heavy-chain (MyHC) isoforms. It was observed that gravitational unloading during space missions and simulated microgravity in ground-based experiments leads to the transformation of some slow-twitch muscle fibers into fast-twitch ones due to changes in the patterns of MyHC gene expression in the postural soleus muscle. The present review covers the facts and mechanistic speculations regarding myosin phenotype remodeling under conditions of gravitational unloading. The review considers the neuronal mechanisms of muscle fiber control and molecular mechanisms of regulation of myosin gene expression, such as inhibition of the calcineurin/NFATc1 signaling pathway, epigenomic changes, and the behavior of specific microRNAs. In the final portion of the review, we discuss the adaptive role of myosin phenotype transformations. PMID:28050266

  3. Intrafusal muscle fibre types in frog spindles.

    PubMed

    Diwan, F H; Ito, F

    1989-04-01

    Muscle spindles from bullfrog semitendinosus, iliofibularis and sartorius muscles were examined with light and electron microscopy. Four types of intrafusal muscle fibre were identified according to their diameter, central nucleation and reticular zone arrangement: a large nuclear bag fibre, a medium nuclear bag fibre, and two types of small nuclear chain fibres with and without a reticular zone, respectively. It is suggested that they are comparable to the nuclear bag1, bag2 and chain fibres in mammalian muscle spindles.

  4. Mechanical and/or neural activity-dependent regulation of soleus muscle fibers of mdx mice

    NASA Astrophysics Data System (ADS)

    Terada, Masahiro; Kawano, Fuminori; Lan, Yong Bo; Matsuoka, Yoshikazu; Wang, Xiao Dong; Ohira, Yoshinobu

    2005-08-01

    Roles of mechanical and/or neural activity in the necrosis -regeneration cycle in the soleus muscle fibers of mdxmicewerestudied. Five-weeks-oldmalemdxand wild type (WT) mice were separated into tenotomy (T), denervation (D), and T+D groups. The distal tendons of the left plantarflexors (soleus, plantaris, and gastrocnemius) were ablated in the T group. The left sciatic nerve was transected at the gluteal region in the D group. The right limb was kept intact as the normal control. Ambulation was allowed after the surgery. Soleus muscle was sampled 14 days after the surgery and analyses were performed in cross-section of whole muscle and in single fibers removed longitudinally. The total fiber number of the untreated muscle was 913±19 (Mean±SEM) and 872±45 in WT and mdx mice, respectively. The fiber number in mdx mice was decreased 48% by T and 31-35% by D and T+D, which induced fiber atrophy, may be due to either inhibited regeneration or stimulated necrosis. Although fibers with central nuclei or necrosis were not observed in WT muscle, 25-40% of fibers (vs. 40% in the contralateral control side) in treated muscles of mdx mice, analyzed cross-sectionally, were central-nucleated. However, fibers with only central nuclei were not detected in the longitudinally isolated fibers of treated groups, may be due to the phenomenon that the fibers with necrosis were lost in the relaxing solution. But % fibers with both central and peripheral nuclei were decreased and those with peripheral nuclei alone were increased by T. In both cross-sectional and longitudinal analyses, the % distribution of the central-nucleated relative to total fiber number was not affected by D, but decreased by T in mdx mice (p>0.05). Myonuclear number per mm of fiber length was identical generally, although the number was increased by T. Furthermore, DNA fragmentation was noted in the mdx fibers with necrosis. These data suggested that the localization of myonuclei, as well as either necrosis or

  5. Work production and work absorption in muscle strips from vertebrate cardiac and insect flight muscle fibers.

    PubMed

    Maughan, D; Moore, J; Vigoreaux, J; Barnes, B; Mulieri, L A

    1998-01-01

    Stretch activation, which underlies the ability of all striated muscles to do oscillatory work, is a prominent feature of both insect flight and vertebrate cardiac muscle. We have examined and compared work-producing and work-absorbing processes in skinned fibers of Drosophila flight muscle, mouse papillary muscle, and human ventricular strips. Using small amplitude sinusoidal length perturbation analysis, we distinguished viscoelastic properties attributable to crossbridge processes from those attributable to other structures of the sarcomere. Work-producing and work-absorbing processes were identified in Ca(2+)-activated fibers by deconvolving complex stiffness data. An 'active' work-producing process ("B"), attributed to crossbridge action, was identified, as were two work-absorbing processes, one attributable to crossbridge action ("C") and the other primarily to viscoelastic properties of parallel passive structures ("A"). At maximal Ca(2+)-activation (pCa 5, 27 degrees C), maximum net power output (processes A, B and C combined) occurs at a frequency of: 1.3 +/- 0.1 Hz for human, 10.9 +/- 2.2 Hz for mouse, and 226 +/- 9 Hz for fly, comparable to the resting heart rate of the human (1 Hz, 37 degrees C) and mouse (10 Hz, 37 degrees C) and to the wing beat frequency of the fruit fly (200 Hz, 22 degrees C). Process B maximal work production per myosin head is 7-11 x 10(-21) J per perturbation cycle, equivalent to approximately 2 kT of energy. Process C maximal work absorption is about the same magnitude. The equivalence suggests the possibility that a thermal ratchet type mechanism operates during small amplitude length perturbations. We speculate that there may be a survival advantage in having a mechanical energy dissipater (i.e., the C process) at work in muscles if they can be injuriously stretched by the system in which they operate.

  6. Microintegrating smooth muscle cells into a biodegradable, elastomeric fiber matrix

    PubMed Central

    Stankus, John J.; Guan, Jianjun; Fujimoto, Kazuro; Wagner, William R.

    2010-01-01

    Electrospinning permits fabrication of biodegradable elastomers into matrices that can resemble the scale and mechanical behavior of the native extracellular matrix. However, achieving high-cellular density and infiltration with this technique remains challenging and time consuming. We have overcome this limitation by electrospraying vascular smooth muscle cells (SMCs) concurrently with electrospinning a biodegradable, elastomeric poly(ester urethane)urea (PEUU). Trypan blue staining revealed no significant decrease in cell viability from the fabrication process and electrosprayed SMCs spread and proliferated similar to control unprocessed SMCs. The resulting SMC microintegrated PEUU constructs were cultured under static conditions or transmural perfusion. Higher cell numbers resulted with perfusion culture with 131% and 98% more viable cells versus static culture at days 4 and 7 (p < 0.05). Fluorescent imaging and hematoxylin and eosin staining further illustrated high cell densities integrated between the elastomeric fibers after perfusion culture. SMC microintegrated PEUU was strong, flexible and anisotropic with tensile strengths ranging from 2.0 to 6.5 MPa and breaking strains from 850 to 1700% dependent on the material axis. The ability to microintegrate smooth muscle or other cell types into a biodegradable elastomer fiber matrix embodies a novel tissue engineering approach that could be applied to fabricate high cell density elastic tissue mimetics, blood vessels or other cardiovascular tissues. PMID:16095685

  7. Microintegrating smooth muscle cells into a biodegradable, elastomeric fiber matrix.

    PubMed

    Stankus, John J; Guan, Jianjun; Fujimoto, Kazuro; Wagner, William R

    2006-02-01

    Electrospinning permits fabrication of biodegradable elastomers into matrices that can resemble the scale and mechanical behavior of the native extracellular matrix. However, achieving high-cellular density and infiltration with this technique remains challenging and time consuming. We have overcome this limitation by electrospraying vascular smooth muscle cells (SMCs) concurrently with electrospinning a biodegradable, elastomeric poly(ester urethane)urea (PEUU). Trypan blue staining revealed no significant decrease in cell viability from the fabrication process and electrosprayed SMCs spread and proliferated similar to control unprocessed SMCs. The resulting SMC microintegrated PEUU constructs were cultured under static conditions or transmural perfusion. Higher cell numbers resulted with perfusion culture with 131% and 98% more viable cells versus static culture at days 4 and 7 (p<0.05). Fluorescent imaging and hematoxylin and eosin staining further illustrated high cell densities integrated between the elastomeric fibers after perfusion culture. SMC microintegrated PEUU was strong, flexible and anisotropic with tensile strengths ranging from 2.0 to 6.5 MPa and breaking strains from 850 to 1,700% dependent on the material axis. The ability to microintegrate smooth muscle or other cell types into a biodegradable elastomer fiber matrix embodies a novel tissue engineering approach that could be applied to fabricate high cell density elastic tissue mimetics, blood vessels or other cardiovascular tissues.

  8. Selective expression of the type 3 isoform of ryanodine receptor Ca{sup 2+} release channel (RyR3) in a subset of slow fibers in diaphragm and cephalic muscles of adult rabbits

    SciTech Connect

    Conti, Antonio; Reggiani, Carlo; Sorrentino, Vincenzo . E-mail: v.sorrentino@unisi.it

    2005-11-11

    The expression pattern of the RyR3 isoform of Ca{sup 2+} release channels was analysed by Western blot in neonatal and adult rabbit skeletal muscles. The results obtained show that the expression of the RyR3 isoform is developmentally regulated. In fact, RyR3 expression was detected in all muscles analysed at 2 and 15 days after birth while, in adult animals, it was restricted to a subset of muscles that includes diaphragm, masseter, pterygoideus, digastricus, and tongue. Interestingly, all of these muscles share a common embryonic origin being derived from the somitomeres or from the cephalic region of the embryo. Immunofluorescence analysis of rabbit skeletal muscle cross-sections showed that RyR3 staining was detected in all fibers of neonatal muscles. In contrast, in those adult muscles expressing RyR3 only a fraction of fibers was labelled. Staining of these muscles with antibodies against fast and slow myosins revealed a close correlation between expression of RyR3 and fibers expressing slow myosin isoform.

  9. Altered distribution of mitochondria in rat soleus muscle fibers after spaceflight

    NASA Technical Reports Server (NTRS)

    Bell, Gordon J.; Martin, Thomas P.; Il'ina-Kakueva, E. I.; Oganov, V. S.; Edgerton, V. R.

    1992-01-01

    The effect of an exposure to microgravity on the distribution of the succinate dehydrogenase (SDH) activity throughout the soleus muscle fibers was investigated by measuring SDH activity throughout the cross section of 20-30 fibers each of the slow-twitch oxidative and fast-twitch oxidative-glycolytic types of fibers in rats exposed to 12.5 days in space aboard Cosmos 1887. It was found that, after the spaceflight, the entire regional distribution of SDH activity was significantly altered (as compared to ground controls) in the slow-twitch oxidative fibers, whereas the fast-twitch oxidative-glycolytic fibers from muscles of flown rats exhibited a significantly lower SDH activity only in their subsarcolemmal region.

  10. In Vivo Microscopy Reveals Extensive Embedding of Capillaries within the Sarcolemma of Skeletal Muscle Fibers

    PubMed Central

    Glancy, Brian; Hsu, Li-Yueh; Dao, Lam; Bakalar, Matthew; French, Stephanie; Chess, David J.; Taylor, Joni L.; Picard, Martin; Aponte, Angel; Daniels, Mathew P.; Esfahani, Shervin; Cushman, Samuel; Balaban, Robert S.

    2013-01-01

    Objective To provide insight into mitochondrial function in vivo, we evaluated the 3D spatial relationship between capillaries, mitochondria, and muscle fibers in live mice. Methods 3D volumes of in vivo murine Tibialis anterior muscles were imaged by multi-photon microscopy (MPM). Muscle fiber type, mitochondrial distribution, number of capillaries, and capillary-to-fiber contact were assessed. The role of myoglobin-facilitated diffusion was examined in myoglobin knockout mice. Distribution of GLUT4 was also evaluated in the context of the capillary and mitochondrial network. Results MPM revealed that 43.6 ± 3.3% of oxidative fiber capillaries had ≥ 50% of their circumference embedded in a groove in the sarcolemma, in vivo. Embedded capillaries were tightly associated with dense mitochondrial populations lateral to capillary grooves and nearly absent below the groove. Mitochondrial distribution, number of embedded capillaries, and capillary-to-fiber contact were proportional to fiber oxidative capacity and unaffected by myoglobin knockout. GLUT4 did not preferentially localize to embedded capillaries. Conclusions Embedding capillaries in the sarcolemma may provide a regulatory mechanism to optimize delivery of oxygen to heterogeneous groups of muscle fibers. We hypothesize that mitochondria locate to paravascular regions due to myofibril voids created by embedded capillaries, not to enhance the delivery of oxygen to the mitochondria. PMID:25279425

  11. Is functional hypertrophy and specific force coupled with the addition of myonuclei at the single muscle fiber level?

    PubMed

    Qaisar, Rizwan; Renaud, Guillaume; Morine, Kevin; Barton, Elisabeth R; Sweeney, H Lee; Larsson, Lars

    2012-03-01

    Muscle force is typically proportional to muscle size, resulting in constant force normalized to muscle fiber cross-sectional area (specific force). Mice overexpressing insulin-like growth factor-1 (IGF-1) exhibit a proportional gain in muscle force and size, but not the myostatin-deficient mice. In an attempt to explore the role of the cytoplasmic volume supported by individual myonuclei [myonuclear domain (MND) size] on functional capacity of skeletal muscle, we have investigated specific force in relation to MND and the content of the molecular motor protein, myosin, at the single muscle fiber level from myostatin-knockout (Mstn(-/-)) and IGF-1-overexpressing (mIgf1(+/+)) mice. We hypothesize that the addition of extra myonuclei is a prerequisite for maintenance of specific force during muscle hypertrophy. A novel algorithm was used to measure individual MNDs in 3 dimensions along the length of single muscle fibers from the fast-twitch extensor digitorum longus and the slow-twitch soleus muscle. A significant effect of the size of individual MNDs in hypertrophic muscle fibers on both specific force and myosin content was observed. This effect was muscle cell type specific and suggested there is a critical volume individual myonuclei can support efficiently. The large MNDs found in fast muscles of Mstn(-/-) mice were correlated with the decrement in specific force and myosin content in Mstn(-/-) muscles. Thus, myostatin inhibition may not be able to maintain the appropriate MND for optimal function.

  12. Effects of Morphological Characteristics of Muscle Fibers on Porcine Growth Performance and Pork Quality

    PubMed Central

    Kim, Jun-Mo; Ryu, Youn Chul

    2016-01-01

    The aim of this study was to investigate the effects of morphological characteristics of porcine muscle fibers on growth performance, muscle fiber characteristics, and pork quality taken from the longissimus dorsi muscle. A total of 239 crossbred pigs (164 castrated males and 75 females) were used in this study. Experimental pigs were categorized by the total number of muscle fiber (TNF: High and Low) and cross sectional area of muscle fiber (CSAF: Large, Middle, and Small). Their combinations were classified into six groups (High-Large, HL; High-Middle, HM; High-Small, HS; Low-Large, LL; Low-Middle, LM; Low-Small, LS). The TNF and CSAF were significantly (p<0.05) correlated with growth rate and carcass productivity, while the only of the type I number had no meaningful relationships excluding the correlation with loin area (p<0.001). The proportion of type I area was positively correlated with pH45 min while the proportion of type IIB area was negatively correlated with pH45 min and pH24 h (p<0.05). Drip loss and protein denaturation had strong relationships with the proportion of type IIB number or area. The HL group exhibited the greatest growth performance. In addition, the HL group had significantly greater values in protein solubility than the other groups. In conclusion, this study suggest that high TNF combined to large CSAF improve the ultimate lean meat productivity and assure normal meat quality simultaneously with increased both proportion of number and area of type I, type IIA muscle fibers and lowered proportion of number and area of type IIB. PMID:27857533

  13. Twitch tension, muscle weight, and fiber area of exercised reinnervating rat skeletal muscle.

    PubMed

    Hie, H B; van Nie, C J; Vermeulen-van der Zee, E

    1982-12-01

    The purpose of this study was to evaluate the effect of dynamic exercise on weight and isometric twitch tension of the reinnervating rat gastrocnemius-plantaris muscle complex as well as on histology of the reinnervating plantaris muscle. Two groups of 6-week-old female Wistar rats, 1 control (n = 17) and 1 experimental (n = 17), were denervated unilaterally by cutting and resecting the sciatic nerve. To effect reinnervation a skin grafting operation was carried out on the nerve so that the gap caused by resection was bridged. The experimental group began exercising on a motor-driven treadmill 18 days following the graft. A progressive training program of 18 weeks of treadmill running, 5 days/week, was carried out by the animals. Training intensity was gradually increased until during the final 3 weeks they were running up a 25% grade at a speed of 720m/hour for 2 hours a day. Exercise did not damage the reinnervating muscle. Absolute wet weight and maximum isometric twitch tension of the reinnervating gastrocnemius-plantaris muscle complex were increased significantly, by 15 1/2% and 30% respectively, after exercise. Training resulted in a significant increase in fiber and muscle cross-sectional areas of the reinnervating plantaris, by 28% and 23% respectively. Exercise brought about no change in total relative amount of connective tissue in the reinnervating plantaris. This study indicates that dynamic exercise has a significant positive effect on the weight, twitch tension and histologic appearance of the reinnervating gastrocnemius-plantaris muscle and thus may enhance their functional recovery. It is likely that this type of training is also effective in the treatment of patients recovering from peripheral nerve injuries.

  14. IP3-dependent, post-tetanic calcium transients induced by electrostimulation of adult skeletal muscle fibers

    PubMed Central

    Casas, Mariana; Figueroa, Reinaldo; Jorquera, Gonzalo; Escobar, Matías; Molgó, Jordi

    2010-01-01

    Tetanic electrical stimulation induces two separate calcium signals in rat skeletal myotubes, a fast one, dependent on Cav 1.1 or dihydropyridine receptors (DHPRs) and ryanodine receptors and related to contraction, and a slow signal, dependent on DHPR and inositol trisphosphate receptors (IP3Rs) and related to transcriptional events. We searched for slow calcium signals in adult muscle fibers using isolated adult flexor digitorum brevis fibers from 5–7-wk-old mice, loaded with fluo-3. When stimulated with trains of 0.3-ms pulses at various frequencies, cells responded with a fast calcium signal associated with muscle contraction, followed by a slower signal similar to one previously described in cultured myotubes. Nifedipine inhibited the slow signal more effectively than the fast one, suggesting a role for DHPR in its onset. The IP3R inhibitors Xestospongin B or C (5 µM) also inhibited it. The amplitude of post-tetanic calcium transients depends on both tetanus frequency and duration, having a maximum at 10–20 Hz. At this stimulation frequency, an increase of the slow isoform of troponin I mRNA was detected, while the fast isoform of this gene was inhibited. All three IP3R isoforms were present in adult muscle. IP3R-1 was differentially expressed in different types of muscle fibers, being higher in a subset of fast-type fibers. Interestingly, isolated fibers from the slow soleus muscle did not reveal the slow calcium signal induced by electrical stimulus. These results support the idea that IP3R-dependent slow calcium signals may be characteristic of distinct types of muscle fibers and may participate in the activation of specific transcriptional programs of slow and fast phenotype. PMID:20837675

  15. Comparison of Muscle Fiber and Meat Quality Characteristics in Different Japanese Quail Lines

    PubMed Central

    Choi, Y. M.; Hwang, S.; Lee, K.

    2016-01-01

    The aim of this study was to compare the growth performance, fiber characteristics of the pectoralis major muscle, and meat quality characteristics in the heavy weight (HW) and random bred control (RBC) quail lines and genders. The HW male exhibited more than two times greater body (245.7 vs 96.1 g, p<0.05) and pectoralis major muscle (PMW; 37.1 vs 11.1 g, p<0.05) weights compared to the RBC female. This growth performance in the HW line was associated with a greater muscle fiber area (1,502 vs 663.0 μm2, p<0.001) compared to the RBC line. Greater muscle mass of the HW male was accompanied by a higher percentage of type IIB fiber compared to the HW female (64.0% vs 51.0%, p<0.05). However, muscle fiber hyperplasia (increase in fiber number) has had a somewhat limited effect on PMW between the two lines. On the other hand, the HW line harboring a higher proportion of type IIB fiber showed rapid pH decline at the early postmortem period (6.23 vs 6.41, p<0.05) and lighter meat surface (53.5 vs 47.3, p<0.05) compared to the RBC line harboring a lower proportion of type IIB fiber. There were no significant differences observed in the measurement of water-holding capacity including drip loss (2.74% vs 3.07%, p>0.05) and cooking loss (21.9% vs 20.4%, p>0.05) between the HW and RBC lines. Therefore, the HW quail line developed by selection from the RBC quail, was slightly different in the meat quality characteristics compared to the RBC line, and a marked difference was found in growth performance between the two quail lines. PMID:27383804

  16. Bion 11 Spaceflight Project: Effect of Weightlessness on Single Muscle Fiber Function in Rhesus Monkeys

    NASA Technical Reports Server (NTRS)

    Fitts, Robert H.; Romatowski, Janell G.; Widrick, Jeffrey J.; DeLaCruz, Lourdes

    1999-01-01

    Although it is well known that microgravity induces considerable limb muscle atrophy, little is known about how weightlessness alters cell function. In this study, we investigated how weightlessness altered the functional properties of single fast and slow striated muscle fibers. Physiological studies were carried out to test the hypothesis that microgravity causes fiber atrophy, a decreased peak force (Newtons), tension (Newtons/cross-sectional area) and power, an elevated peak rate of tension development (dp/dt), and an increased maximal shortening velocity (V(sub o)) in the slow type I fiber, while changes in the fast-twitch fiber are restricted to atrophy and a reduced peak force. For each fiber, we determined the peak force (P(sub o)), V(sub o), dp/dt, the force-velocity relationship, peak power, the power-force relationship, the force-pCa relationship, and fiber stiffness. Biochemical studies were carried out to assess the effects of weightlessness on the enzyme and substrate profile of the fast- and slow-twitch fibers. We predicted that microgravity would increase resting muscle glycogen and glycolytic metabolism in the slow fiber type, while the fast-twitch fiber enzyme profile would be unaltered. The increased muscle glycogen would in part result from an elevated hexokinase and glycogen synthase. The enzymes selected for study represent markers for mitochondrial function (citrate synthase and 0-hydroxyacyl-CoA dehydrogenase), glycolysis (Phosphofructokinase and lactate dehydrogenase), and fatty acid transport (Carnitine acetyl transferase). The substrates analyzed will include glycogen, lactate, adenosine triphosphate, and phosphocreatine.

  17. Fiber-type dosimeter with improved illuminator

    DOEpatents

    Fox, Richard J.

    1987-01-01

    A single-piece, molded plastic, Cassigrainian-type condenser arrangement is incorporated in a tubular-shaped personal pocket dosimeter of the type which combines an ionization chamber with an optically-read fiber electrometer to provide improved illumination of the electrometer fiber. The condenser routes incoming light from one end of the dosimeter tubular housing around a central axis charging pin assembly and focuses the light at low angles to the axis so that it falls within the acceptance angle of the electrometer fiber objective lens viewed through an eyepiece lens disposed in the opposite end of the dosimeter. This results in improved fiber illumination and fiber image contrast.

  18. Fiber-type dosimeter with improved illuminator

    DOEpatents

    Fox, R.J.

    1985-12-23

    A single-piece, molded plastic, Cassigrainian-type condenser arrangement is incorporated in a tubular-shaped personal pocket dosimeter of the type which combines an ionization chamber with an optically-read fiber electrometer to provide improved illumination of the electrometer fiber. The condenser routes incoming light from one end of the dosimeter tubular housing around a central axis charging pin assembly and focuses the light at low angles to the axis so that it falls within the acceptance angle of the electrometer fiber objective lens viewed through an eyepiece lens disposed in the opposite end of the dosimeter. This results in improved fiber illumination and fiber image contrast.

  19. Inhibition of platelet-derived growth factor signaling prevents muscle fiber growth during skeletal muscle hypertrophy.

    PubMed

    Sugg, Kristoffer B; Korn, Michael A; Sarver, Dylan C; Markworth, James F; Mendias, Christopher L

    2017-03-01

    The platelet-derived growth factor receptors alpha and beta (PDGFRα and PDGFRβ) mark fibroadipogenic progenitor cells/fibroblasts and pericytes in skeletal muscle, respectively. While the role that these cells play in muscle growth and development has been evaluated, it was not known whether the PDGF receptors activate signaling pathways that control transcriptional and functional changes during skeletal muscle hypertrophy. To evaluate this, we inhibited PDGFR signaling in mice subjected to a synergist ablation muscle growth procedure, and performed analyses 3 and 10 days after induction of hypertrophy. The results from this study indicate that PDGF signaling is required for fiber hypertrophy, extracellular matrix production, and angiogenesis that occur during muscle growth.

  20. Functional properties of slow and fast gastrocnemius muscle fibers after a 17-day spaceflight

    NASA Technical Reports Server (NTRS)

    Widrick, J. J.; Romatowski, J. G.; Norenberg, K. M.; Knuth, S. T.; Bain, J. L.; Riley, D. A.; Trappe, S. W.; Trappe, T. A.; Costill, D. L.; Fitts, R. H.

    2001-01-01

    The purpose of this investigation was to study the effects of a 17-day spaceflight on the contractile properties of individual fast- and slow-twitch fibers isolated from biopsies of the fast-twitch gastrocnemius muscle of four male astronauts. Single chemically skinned fibers were studied during maximal Ca2+-activated contractions with fiber myosin heavy chain (MHC) isoform expression subsequently determined by SDS gel electrophoresis. Spaceflight had no significant effect on the mean diameter or specific force of single fibers expressing type I, IIa, or IIa/IIx MHC, although a small reduction in average absolute force (P(o)) was observed for the type I fibers (0.68 +/- 0.02 vs. 0.64 +/- 0.02 mN, P < 0.05). Subject-by-flight interactions indicated significant intersubject variation in response to the flight, as postflight fiber diameter and P(o) where significantly reduced for the type I and IIa fibers obtained from one astronaut and for the type IIa fibers from another astronaut. Average unloaded shortening velocity [V(o), in fiber lengths (FL)/s] was greater after the flight for both type I (0.60 +/- 0.03 vs. 0.76 +/- 0.02 FL/s) and IIa fibers (2.33 +/- 0.25 vs. 3.10 +/- 0.16 FL/s). Postflight peak power of the type I and IIa fibers was significantly reduced only for the astronaut experiencing the greatest fiber atrophy and loss of P(o). These results demonstrate that 1) slow and fast gastrocnemius fibers show little atrophy and loss of P(o) but increased V(o) after a typical 17-day spaceflight, 2) there is, however, considerable intersubject variation in these responses, possibly due to intersubject differences in in-flight physical activity, and 3) in these four astronauts, fiber atrophy and reductions in P(o) were less for slow and fast fibers obtained from the phasic fast-twitch gastrocnemius muscle compared with slow and fast fibers obtained from the slow antigravity soleus [J. J. Widrick, S. K. Knuth, K. M. Norenberg, J. G. Romatowski, J. L. W. Bain, D. A

  1. Size and metabolic properties of fibers in rat fast-twitch muscles after hindlimb suspension

    NASA Technical Reports Server (NTRS)

    Roy, Roland R.; Bello, Maureen A.; Bouissou, Phillip; Edgerton, V. Reggie

    1987-01-01

    The effect of hind-limb suspension (HS) on single fibers of the medial gastrocnemius (MG) and the tibialis anterior (TA) muscles were studied in rats. Fiber area and the activities of succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPD) were determined in tissue sections using an image analysis system. After 28 days of HS, the MG atrophied 28 percent, whereas the TA weight was maintained. Both dark- and light-ATPase fibers in the deep region of the MG had decreased cross-sectional areas following HS, with the atrophic response being twice as great in the light-ATPase fibers than in the dark-ATPase fibers. Following HS, mean SDH activities of both fiber types were significantly lower in the MG and TA than in the CON; by contrast, mean GPD activities were either maintained at the CON level or were higher in both MG and TA muscles. The data suggest an independence of the mechanisms determining the muscle fiber size and the metabolic adaptations associated with HS.

  2. Arrest is a regulator of fiber-specific alternative splicing in the indirect flight muscles of Drosophila.

    PubMed

    Oas, Sandy T; Bryantsev, Anton L; Cripps, Richard M

    2014-09-29

    Drosophila melanogaster flight muscles are distinct from other skeletal muscles, such as jump muscles, and express several uniquely spliced muscle-associated transcripts. We sought to identify factors mediating splicing differences between the flight and jump muscle fiber types. We found that the ribonucleic acid-binding protein Arrest (Aret) is expressed in flight muscles: in founder cells, Aret accumulates in a novel intranuclear compartment that we termed the Bruno body, and after the onset of muscle differentiation, Aret disperses in the nucleus. Down-regulation of the aret gene led to ultrastructural changes and functional impairment of flight muscles, and transcripts of structural genes expressed in the flight muscles became spliced in a manner characteristic of jump muscles. Aret also potently promoted flight muscle splicing patterns when ectopically expressed in jump muscles or tissue culture cells. Genetically, aret is located downstream of exd (extradenticle), hth (homothorax), and salm (spalt major), transcription factors that control fiber identity. Our observations provide insight into a transcriptional and splicing regulatory network for muscle fiber specification.

  3. The Relationships Among Isokinetic Endurance, Initial Strength Level, and Fiber Type.

    ERIC Educational Resources Information Center

    Clarkson, Priscilla M.; And Others

    1982-01-01

    Knee extension isokinetic peak torque was assessed at four angular velocities, and isokinetic endurance was assessed in eight college age men. Muscle fiber type was determined and related to isokinetic strength and fatigability. Results indicate that factors other than fiber type and initial strength level must influence the rate of isokinetic…

  4. Equilibrium distribution of ions in a muscle fiber.

    PubMed Central

    Maughan, D W; Godt, R E

    1989-01-01

    We have developed a mathematical description of the equilibrium (Donnan) distribution of mobile ions between two phases containing fixed charges. This differs from the classical Donnan derivation by including mobile polyvalent ions such as those present in intact muscle fibers and in solutions used with skinned muscle fibers. Given the average concentrations of ionic species present in intact frog muscle, we calculate that the myofibrillar fixed charge density (-42 meq/liter cytoplasmic fluid) is in close agreement with estimates from amino acid analysis of myofibrillar proteins. As expected, with negative fixed charges in the myofibril, anions are excluded from the myofibrillar space while cations are concentrated in this space; the ratio between the average intra- and extramyofibrillar concentrations for an ion of valence n is (1.11)n. This model allowed us to design a bathing solution for skinned muscle fibers in which the intramyofibrillar ion concentrations closely approximate those found in intact frog muscle cells. Our model, applied to the A- and I-bands of the sarcomere, suggests that likely differences in fixed charge densities in these regions accounts for only a small fraction of the extreme concentration of phosphocreatine observed in the I-bands of intact frog muscle. PMID:2819235

  5. Morphometric analysis of somatotropic cells of the adenohypophysis and muscle fibers of the psoas muscle in the process of aging in humans.

    PubMed

    Antić, Vladimir M; Stefanović, Natalija; Jovanović, Ivan; Antić, Milorad; Milić, Miroslav; Krstić, Miljan; Kundalić, Braca; Milošević, Verica

    2015-07-01

    The aim of this research was to quantify changes of the adenohypophyseal somatotropes and types 1 and 2 muscle fibers with aging, as well as to establish mutual interactions and correlations with age. Material was samples of hypophysis and psoas major muscle of 27 cadavers of both genders, aged from 30 to 90 years. Adenohypophyseal and psoas major tissue sections were immunohistochemically processed and stained by anti-human growth hormone and anti-fast myosin antibodies, respectively. Morphometric analysis was performed by ImageJ. Results of morphometric analysis showed a significant increase in the somatotrope area, and significant decrease in somatotrope volume density and nucleocytoplasmic ratio with age. Cross-sectional areas of types 1 and 2, and volume density of type 2 muscle fibers decreased significantly with age. One Way ANOVA showed that the latter cited changes in the somatotropes and types 1 and 2 muscle fibers mostly become significant after the age of 70. Significant positive correlation was observed between the area of the somatotropes and volume density of type 2 muscle fibers. A significant negative correlation was detected between the nucleocytoplasmic ratio of the somatotropes and cross-sectional areas of types 1 and 2 muscle fibers. So, it can be concluded that after the age of 70, there is significant loss of the anterior pituitary's somatotropes associated with hypertrophy and possible functional decline of the remained cells. Age-related changes in the somatotropes are correlated with the simultaneous atrophy of type 1, as well as with the atrophy and loss of type 2 muscle fibers.

  6. Severely Atrophic Human Muscle Fibers With Nuclear Misplacement Survive Many Years of Permanent Denervation

    PubMed Central

    Carraro, Ugo; Kern, Helmut

    2016-01-01

    Likewise in rodents, after complete spinal cord injury (SCI) the lower motor neuron (LMN) denervated human muscle fibers lose completely the myofibrillar apparatus and the coil distribution of myonuclei that are relocated in groups (nuclear clumps) in the center of severely atrophic muscle fibers. Up to two years of LMN denervation the muscle fibers with nuclear clumps are very seldom, but in this cohort of patients the severely atrophic muscle fibers are frequent in muscle biopsies harvested three to six years after SCI. Indeed, the percentage increased to 27 ± 9% (p< 0.001), and then abruptly decreased from the 6th year onward, when fibrosis takes over to neurogenic muscle atrophy. Immunohistochemical analyses shown that nuclear misplacements occurred in both fast and slow muscle fibers. In conclusion, human muscle fibers survive permanent denervation much longer than generally accepted and relocation of nuclei is a general behavior in long term denervated muscle fibers. PMID:27478559

  7. Identification and quantification in single muscle fibers of four isoforms of parvalbumin in the iliofibularis muscle of Xenopus laevis.

    PubMed

    Simonides, W S; van Hardeveld, C

    1989-10-05

    The major parvalbumins present in the iliofibularis muscle of Xenopus laevis were identified and the total parvalbumin content of different types of single fibers of this muscle was determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS). The criteria used in the identification of proteins as parvalbumins were: a relative molecular mass (Mr) between 10,000 and 14,000, an isoelectric point (pI) between 4.0 and 5.0, and a Ca2+-dependent mobility when run on a polyacrylamide gel in the absence of SDS. Four proteins were thus identified as parvalbumins: PA1, Mr 14,000, pI 4.90; PA2, Mr 11,000, pI 4.90; PA3, Mr 11,000, pI 4.95; and PA4, Mr 11,000, pI 4.25. An ultraviolet absorbance spectrum characteristic of parvalbumins was recorded for a purified preparation of these four proteins. Because the apparent Mr of rabbit parvalbumin in the gel system used was 14,000, whereas the true value is 12,100, it is not excluded that the Mr of component PA1 of 14,000 is an overestimation. The total parvalbumin content of muscles and single muscle fibers was determined using the supernatant obtained after centrifugation of tissue homogenates. Analysis of the protein pattern after electrophoresis in the presence of SDS of this fraction indicated that the Mr 14,000 and 11,000 protein bands contained virtually only parvalbumin. Quantification of the total parvalbumin content of relatively fast (type 1) and slow (type 2) contracting and relaxing single muscle fibers, using laser densitometric analysis of minigels, yielded mean values (mg protein/g wet wt., +/- S.D.) of 5.2 +/- 0.8 for nine type 1 fibers, and 1.9 +/- 1.0 for five type 2 fibers. Both fiber types contained about 2.5-times as much of the Mr 14,000 isoform relative to the combined Mr 11,000 isoforms.

  8. A new method to study in vivo protein synthesis in slow- and fast-twitch muscle fibers and initial measurements in humans.

    PubMed

    Dickinson, J M; Lee, J D; Sullivan, B E; Harber, M P; Trappe, S W; Trappe, T A

    2010-05-01

    The aim of this study was to develop an approach to directly assess protein fractional synthesis rate (FSR) in isolated human muscle fibers in a fiber type-specific fashion. Individual muscle fibers were isolated from biopsies of the vastus lateralis (VL) and soleus (SOL) obtained from eight young men during a primed, continuous infusion of [5,5,5-(2)H3]leucine performed under basal conditions. To determine mixed protein FSR, a portion of each fiber was used to identify fiber type, fibers of the same type were pooled, and the [5,5,5-(2)H3]leucine enrichment was determined via GC-MS. Processing isolated slow-twitch [myosin heavy chain (MHC) I] and fast-twitch (MHC IIa) fibers for mixed protein bound [5,5,5-(2)H3]leucine enrichment yielded mass ion chromatographic peaks that were similar in shape, abundance, and measurement reliability as tissue homogenates. In the VL, MHC I fibers exhibited a 33% faster (P<0.05) mixed protein FSR compared with MHC IIa fibers (0.068+/-0.006 vs. 0.051+/-0.003%/h). MHC I fibers from the SOL (0.060+/-0.005%/h) and MHC I fibers from the VL displayed similar (P>0.05) mixed protein FSR. Feasibility of processing isolated human muscle fibers for analysis of myofibrillar protein [5,5,5-(2)H3]leucine enrichment was also confirmed in non-fiber-typed pooled fibers from the VL. These methods can be applied to the study of fiber type-specific responses in human skeletal muscle. The need for this level of investigation is underscored by the different contributions of each fiber type to whole muscle function and the numerous distinct adaptive functional and metabolic changes in MHC I and MHC II fibers originating from the same muscle.

  9. Modulation of Muscle Fiber Compositions in Response to Hypoxia via Pyruvate Dehydrogenase Kinase-1

    PubMed Central

    Nguyen, Daniel D.; Kim, Gyuyoup; Pae, Eung-Kwon

    2016-01-01

    Muscle fiber-type changes in hypoxic conditions in accordance with pyruvate dehydrogenase kinase (Pdk)-1 and hypoxia inducible factor (Hif)-1α were investigated in rats. Hif-1α and its down-stream molecule Pdk-1 are well known for readily response to hypoxia. We questioned their roles in relation to changes in myosin heavy chain (MyHC) composition in skeletal muscles. We hypothesize that the level of Pdk-1 with respect to the level of Hif-1α determines MyHC composition of the muscle in rats in hypoxia. Young male rats were housed in a chamber maintained at 11.5% (for sustained hypoxia) or fluctuating between 11.5 and 20.8% (for intermittent hypoxia or IH) oxygen levels. Then, muscle tissues from the geniohyoid (GH), soleus, and anterior tibialis (TA) were obtained at the end of hypoxic conditionings. After both hypoxic conditionings, protein levels of Pdk-1 and Hif-1 increased in GH muscles. GH muscles in acute sustained hypoxia favor an anaerobic glycolytic pathway, resulting in an increase in glycolytic MyHC IIb protein-rich fibers while maintain original fatigue-resistant MyHC IIa protein in the fibers; thus, the numbers of IIa- and IIb MyHC co-expressing fibers increased. Exogenous Pdk-1 over-expression using plasmid vectors elevated not only the glycolytic MyHC IIb, but also IIx as well as IIa expressions in C2C12 myotubes in ambient air significantly. The increase of dual expression of IIa- and IIb MyHC proteins in fibers harvested from the geniohyoid muscle has a potential to improve endurance as shown in our fatigability tests. By increasing the Pdk-1/Hif-1 ratio, a mixed-type muscle could alter endurance within the innate characteristics of the muscle toward more fatigue resistant. We conclude that an increased Pdk-1 level in skeletal muscle helps maintain MyHC compositions to be a fatigue resistant mixed-type muscle. PMID:28018235

  10. Modulation of Muscle Fiber Compositions in Response to Hypoxia via Pyruvate Dehydrogenase Kinase-1.

    PubMed

    Nguyen, Daniel D; Kim, Gyuyoup; Pae, Eung-Kwon

    2016-01-01

    Muscle fiber-type changes in hypoxic conditions in accordance with pyruvate dehydrogenase kinase (Pdk)-1 and hypoxia inducible factor (Hif)-1α were investigated in rats. Hif-1α and its down-stream molecule Pdk-1 are well known for readily response to hypoxia. We questioned their roles in relation to changes in myosin heavy chain (MyHC) composition in skeletal muscles. We hypothesize that the level of Pdk-1 with respect to the level of Hif-1α determines MyHC composition of the muscle in rats in hypoxia. Young male rats were housed in a chamber maintained at 11.5% (for sustained hypoxia) or fluctuating between 11.5 and 20.8% (for intermittent hypoxia or IH) oxygen levels. Then, muscle tissues from the geniohyoid (GH), soleus, and anterior tibialis (TA) were obtained at the end of hypoxic conditionings. After both hypoxic conditionings, protein levels of Pdk-1 and Hif-1 increased in GH muscles. GH muscles in acute sustained hypoxia favor an anaerobic glycolytic pathway, resulting in an increase in glycolytic MyHC IIb protein-rich fibers while maintain original fatigue-resistant MyHC IIa protein in the fibers; thus, the numbers of IIa- and IIb MyHC co-expressing fibers increased. Exogenous Pdk-1 over-expression using plasmid vectors elevated not only the glycolytic MyHC IIb, but also IIx as well as IIa expressions in C2C12 myotubes in ambient air significantly. The increase of dual expression of IIa- and IIb MyHC proteins in fibers harvested from the geniohyoid muscle has a potential to improve endurance as shown in our fatigability tests. By increasing the Pdk-1/Hif-1 ratio, a mixed-type muscle could alter endurance within the innate characteristics of the muscle toward more fatigue resistant. We conclude that an increased Pdk-1 level in skeletal muscle helps maintain MyHC compositions to be a fatigue resistant mixed-type muscle.

  11. Longitudinal decline of lower extremity muscle power in healthy and mobility-limited older adults: influence of muscle mass, strength, composition, neuromuscular activation and single fiber contractile properties

    PubMed Central

    Reid, Kieran F.; Pasha, Evan; Doros, Gheorghe; Clark, David J.; Patten, Carolynn; Phillips, Edward M.; Frontera, Walter R.; Fielding, Roger A.

    2013-01-01

    Purpose This longitudinal study examined the major physiological mechanisms that determine the age-related loss of lower extremity muscle power in two distinct groups of older humans. We hypothesized that after ~ 3 years of follow-up, mobility-limited older adults (mean age: 77.2 ± 4, n = 22, 12 females) would have significantly greater reductions in leg extensor muscle power compared to healthy older adults (74.1 ± 4, n = 26, 12 females). Methods Mid-thigh muscle size and composition were assessed using computed tomography. Neuromuscular activation was quantified using surface electromyography and vastus lateralis single muscle fibers were studied to evaluate intrinsic muscle contractile properties. Results At follow-up, the overall magnitude of muscle power loss was similar between groups: mobility-limited: −8.5% vs. healthy older: −8.8%, P > 0.8. Mobility-limited elders had significant reductions in muscle size (−3.8%, P< 0.01) and strength (−5.9%, P< 0.02), however, these parameters were preserved in healthy older (P ≥ 0.7). Neuromuscular activation declined significantly within healthy older but not in mobility-limited participants. Within both groups, the cross sectional areas of type I and type IIA muscle fibers were preserved while substantial increases in single fiber peak force ( > 30%), peak power (> 200%) and unloaded shortening velocity (>50%) were elicited at follow-up. Conclusion Different physiological mechanisms contribute to the loss of lower extremity muscle power in healthy older and mobility-limited older adults. Neuromuscular changes may be the critical early determinant of muscle power deficits with aging. In response to major whole muscle decrements, major compensatory mechanisms occur within the contractile properties of surviving single muscle fibers in an attempt to restore overall muscle power and function with advancing age. PMID:24122149

  12. Contractile properties of thin (actin) filament-reconstituted muscle fibers.

    PubMed

    Ishiwata, S; Funatsu, T; Fujita, H

    1998-01-01

    Selective removal and reconstitution of the components of muscle fibers (fibrils) is a useful means of examining the molecular mechanism underlying the formation of the contractile apparatus. In addition, this approach is powerful for examining the structure-function relationship of a specific component of the contractile system. In previous studies, we have achieved the partial structural and functional reconstitution of thin filaments in the skeletal contractile apparatus and full reconstitution in the cardiac contractile apparatus. First, all thin filaments other than short fragments at the Z line were removed by treatment with plasma gelsolin, an actin filament-severing protein. Under these conditions, no active tension could be generated. By incorporating exogenous actin into these thin filament-free fibers, actin filaments were reconstituted by polymerization on the short actin fragments remaining at the Z line, and active tension, which was insensitive to Ca2+, was restored. The active tension after the reconstitution of thin filaments reached as high as 30% of the original level in skeletal muscle, while it reached 140% in cardiac muscle. The augmentation of tension in cardiac muscle is mainly attributable to the elongation of reconstituted filaments, longer than the average length of thin filaments in an intact muscle. These results indicate that a muscle contractile apparatus with a high order structure and function can be constructed by the self-assembly of constituent proteins. Recently, we applied this reconstitution system to the study of the mechanism of spontaneous oscillatory contraction (SPOC) in thin (actin) filament-reconstituted cardiac muscle fibers. As a result, we found that SPOC occurs even in regulatory protein-free actin filament-reconstituted fibers (Fujita & Ishiwata, manuscript submitted), although the SPOC conditions were slightly different from the standard SPOC conditions. This result strongly suggests that spontaneous oscillation

  13. Contractile function of single muscle fibers after hindlimb suspension

    NASA Technical Reports Server (NTRS)

    Gardetto, P. R.; Schluter, J. M.; Fitts, R. H.

    1989-01-01

    The effects of two weeks of hind-limb suspension (HS) on the functional properties of slow-twitch and fast-twitch single fibers isolated from the predominantly slow-twitch soleus and fast-twitch gastrocnemius of the suspended leg of rats were investigated. Single fibers were suspended between a motor arm and force transducer, and, after their functional properties were studied, the fiber type was established by the myosin heavy chain analysis. It was found that, after HS, the greatest decrease in diameter and a reduction in peak tension occurred in slow-twitch fibers from soleus, followed by slow-twitch fibers from gastrocnemius. Fast-twitch fibers from the red gastrocnemius showed a significant reduction in diameter but no change in peak tension. No effect of HS was observed on the diameter of the fast-twitch fibers from the white gastsrocnemius (which is known to contain 87 percent fast glycolytic fibers).

  14. Segmental distribution of myosin heavy chain isoforms within single muscle fibers.

    PubMed

    Zhang, Ming; Gould, Maree

    2017-02-18

    Despite many studies looking at the distribution of myosin heavy chain (MHC) isoforms across a transverse section of muscle, knowledge of MHC distribution along the longitudinal axis of a single skeletal muscle fiber has been relatively overlooked. Immunocytochemistry was performed on serial sections of rat extensor digitorum longus (EDL) muscle to identify MHC types I, IIA, IIX, IIY and IIB. Sixteen fascicles which contained a total of 362 fibers were randomly and systematically sampled from the 3 EDL muscles. All MHC type I and type II isoforms were expressed. Segmental expression occurred within a very limited segment. MHC isoform expression followed the accepted traditional order from I&cenveo_unknown_entity_wingdings_F0F3;IIA&cenveo_unknown_entity_wingdings_F0F3;IIX&cenveo_unknown_entity_wingdings_F0F3;IIB, however in some samples expression of an isoform was circumvented from IIB to I or from I to IIB directly. Segmental distribution of MHC isoforms along a single muscle fiber may be due to the myonuclear domain. This article is protected by copyright. All rights reserved.

  15. ATP consumption and efficiency of human single muscle fibers with different myosin isoform composition.

    PubMed Central

    He, Z H; Bottinelli, R; Pellegrino, M A; Ferenczi, M A; Reggiani, C

    2000-01-01

    Chemomechanical transduction was studied in single fibers isolated from human skeletal muscle containing different myosin isoforms. Permeabilized fibers were activated by laser-pulse photolytic release of 1.5 mM ATP from p(3)-1-(2-nitrophenyl)ethylester of ATP. The ATP hydrolysis rate in the muscle fibers was determined with a fluorescently labeled phosphate-binding protein. The effects of varying load and shortening velocity during contraction were investigated. The myosin isoform composition was determined in each fiber by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. At 12 degrees C large variations (three- to fourfold) were found between slow and fast (2A and 2A-2B) fibers in their maximum shortening velocity, peak power output, velocity at which peak power is produced, isometric ATPase activity, and tension cost. Isometric tension was similar in all fiber groups. The ATP consumption rate increased during shortening in proportion to shortening velocity. At 12 degrees C the maximum efficiency was similar (0.21-0.27) for all fiber types and was reached at a higher speed of shortening for the faster fibers. In all fibers, peak efficiency increased to approximately 0.4 when the temperature was raised from 12 degrees C to 20 degrees C. The results were simulated with a kinetic scheme describing the ATPase cycle, in which the rate constant controlling ADP release is sensitive to the load on the muscle. The main difference between slow and fast fibers was reproduced by increasing the rate constant for the hydrolysis step, which was rate limiting at low loads. Simulation of the effect of increasing temperature required an increase in the force per cross-bridge and an acceleration of the rate constants in the reaction pathway. PMID:10920025

  16. Myosin flares and actin leptomeres as myofibril assembly/disassembly intermediates in sonic muscle fibers.

    PubMed

    Nahirney, Patrick C; Fischman, Donald A; Wang, Kuan

    2006-04-01

    The sonic muscle of type 1 male midshipman fish produces loud and enduring mating calls. Each sonic muscle fiber contains a tubular contractile apparatus with radially arranged myofibrillar plates encased in a desmin-rich cytoskeleton that is anchored to broad Z bands (approximately 1.2 micro m wide). Immunomicroscopy has revealed patches of myosin-rich "flares" emanating from the contractile tubes into the peripheral sarcoplasm along the length of the fibers. These flares contain swirls of thick filaments devoid of associated thin filaments. In other regions of the sarcoplasm at the inner surface of the sarcolemma and near Z bands, abundant ladder-like leptomeres occur with rungs every 160 nm. Leptomeres consist of dense arrays of filaments (approximately 4 nm) with a structure that resembles myofibrillar Z band structure. We propose that flares and leptomeres are distinct filamentous arrays representing site-specific processing of myofibrillar components during the assembly and disassembly of the sarcomere. Recent reports that myosin assembles into filamentous aggregates before incorporating into the A band in the skeletal muscles of vertebrates and Caenorhabditis elegans suggest that sonic fibers utilize a similar pathway. Thus, sonic muscle fibers, with their tubular design and abundant sarcoplasmic space, may provide an attractive muscle model to identify myofibrillar intermediates by structural and molecular techniques.

  17. Biochemical adaptations of antigravity muscle fibers to disuse atrophy

    NASA Technical Reports Server (NTRS)

    Booth, F. W.

    1978-01-01

    Studies are presented in four parts of this report. The four parts include; (1) studies to gain information on the molecular basis of atrophy by antigravity muscle; (2) studies on the work capacity of antigravity muscles during atrophy and during recovery from atrophy; (3) studies on recovery of degenerated antigravity fibers after removal of hind-limb casts; and (4) studies on the atrophy and recovery of bone. The philosophy of these studies was to identify the time sequence of events in the soleus muscle of the rat following immobilization of the hind limbs, so that the length of the soleus muscle within the fixed limb is less than its resting length. In two separate studies, no decline in the weight of the soleus muscle could be detected during the first 72 hours of limb immobilization.

  18. The muscle fiber type–fiber size paradox: hypertrophy or oxidative metabolism?

    PubMed Central

    van Wessel, T.; de Haan, A.; van der Laarse, W. J.

    2010-01-01

    An inverse relationship exists between striated muscle fiber size and its oxidative capacity. This relationship implies that muscle fibers, which are triggered to simultaneously increase their mass/strength (hypertrophy) and fatigue resistance (oxidative capacity), increase these properties (strength or fatigue resistance) to a lesser extent compared to fibers increasing either of these alone. Muscle fiber size and oxidative capacity are determined by the balance between myofibrillar protein synthesis, mitochondrial biosynthesis and degradation. New experimental data and an inventory of critical stimuli and state of activation of the signaling pathways involved in regulating contractile and metabolic protein turnover reveal: (1) higher capacity for protein synthesis in high compared to low oxidative fibers; (2) competition between signaling pathways for synthesis of myofibrillar proteins and proteins associated with oxidative metabolism; i.e., increased mitochondrial biogenesis via AMP-activated protein kinase attenuates the rate of protein synthesis; (3) relatively higher expression levels of E3-ligases and proteasome-mediated protein degradation in high oxidative fibers. These observations could explain the fiber type–fiber size paradox that despite the high capacity for protein synthesis in high oxidative fibers, these fibers remain relatively small. However, it remains challenging to understand the mechanisms by which contractile activity, mechanical loading, cellular energy status and cellular oxygen tension affect regulation of fiber size. Therefore, one needs to know the relative contribution of the signaling pathways to protein turnover in high and low oxidative fibers. The outcome and ideas presented are relevant to optimizing treatment and training in the fields of sports, cardiology, oncology, pulmonology and rehabilitation medicine. Electronic supplementary material The online version of this article (doi:10.1007/s00421-010-1545-0) contains

  19. Muscle type-specific myosin isoforms in crustacean muscles.

    PubMed

    LaFramboise, W A; Griffis, B; Bonner, P; Warren, W; Scalise, D; Guthrie, R D; Cooper, R L

    2000-01-01

    Differential expression of multiple myosin heavy chain (MyHC) genes largely determines the diversity of critical physiological, histochemical, and enzymatic properties characteristic of skeletal muscle. Hypotheses to explain myofiber diversity range from intrinsic control of expression based on myoblast lineage to extrinsic control by innervation, hormones, and usage. The unique innervation and specialized function of crayfish (Procambarus clarkii) appendicular and abdominal musculature provide a model to test these hypotheses. The leg opener and superficial abdominal extensor muscles are innervated by tonic excitatory motoneurons. High resolution SDS-PAGE revealed that these two muscles express the same MyHC profile. In contrast, the deep abdominal extensor muscles, innervated by phasic motoneurons, express MyHC profiles different from the tonic profiles. The claw closer muscles are dually innervated by tonic and phasic motoneurons and a mixed phenotype was observed, albeit biased toward the phasic profile seen in the closer muscle. These results indicate that multiple MyHC isoforms are present in the crayfish and that differential expression is associated with diversity of muscle type and function.

  20. Fiber optic biofluorometer for physiological research on muscle slices

    NASA Astrophysics Data System (ADS)

    Belz, Mathias; Dendorfer, Andreas; Werner, Jan; Lambertz, Daniel; Klein, Karl-Friedrich

    2016-03-01

    A focus of research in cell physiology is the detection of Ca2+, NADH, FAD, ATPase activity or membrane potential, only to name a few, in muscle tissues. In this work, we report on a biofluorometer using ultraviolet light emitting diodes (UV-LEDs), optical fibers and two photomultipliers (PMTs) using synchronized fluorescence detection with integrated background correction to detect free calcium, Ca2+, in cardiac muscle tissue placed in a horizontal tissue bath and a microscope setup. Fiber optic probes with imaging optics have been designed to transport excitation light from the biofluorometer's light output to a horizontal tissue bath and to collect emission light from a tissue sample of interest to two PMTs allowing either single excitation / single emission or ratiometric, dual excitation / single emission or single excitation / dual emission fluorescence detection of indicator dyes or natural fluorophores. The efficient transport of light from the excitation LEDs to the tissue sample, bleaching effects of the excitation light in both, polymer and fused silica-based fibers will be discussed. Furthermore, a new approach to maximize light collection of the emission light using high NA fibers and high NA coupling optics will be shown. Finally, first results on Ca2+ measurements in cardiac muscle slices in a traditional microscope setup and a horizontal tissue bath using fiber optic probes will be introduced and discussed.

  1. Morphology of the lumbar transversospinal muscles examined in a mouse bearing a muscle fiber-specific nuclear marker.

    PubMed

    Cornwall, Jon; Deries, Marianne; Duxson, Marilyn

    2010-12-01

    Although the morphology of human lumbar transversospinal (TSP) muscles has been studied, little is known about the structure of these muscles in the mouse (Mus musculus). Such information is relevant given mice are often used as a "normal" phenotype for studies modeling human development. This study describes the gross morphology, muscle fiber arrangement, and innervation pattern of the mouse lumbar TSP muscles. A unique feature of the study is the use of a transgenic mouse line bearing a muscle-specific nuclear marker that allows clear delineation of muscle fiber and connective tissue boundaries. The lumbar TSP muscles of five mice were examined bilaterally; at each spinal level muscles attached to the caudal edge of the spinous process and passed caudally as a single complex unit. Fibers progressively terminated over the four vertebral segments caudad, with multiple points of muscle fiber attachment on each vertebra. Motor endplates, defined with acetylcholinesterase histochemistry, were consistently located half way along each muscle fiber, regardless of length, with all muscle fibers arranged in-parallel rather than in-series. These results provide information relevant to interpretation of developmental and functional studies involving this muscle group in the mouse and show mouse lumbar TSP muscles are different in form to descriptions of equivalent muscles in humans and horses.

  2. Experiment K-6-07. Metabolic and morphologic properties of muscle fibers after spaceflight

    NASA Technical Reports Server (NTRS)

    Edgerton, R.; Miu, B.; Martin, Thomas P.; Roy, R.; Marini, J.; Leger, J. J.; Oganov, V.; Ilyina-Kakueva, E.

    1990-01-01

    The present study demonstrates that the general capability of skeletal muscle to maintain its proteins decreases rapidly in response to space flight. The present findings suggest further that the magnitude of enzymatic and cell volumes changes in response to space flight depend on several factors including the muscle and its fiber type composition. It appears that in order to associate physiological relevance to the observed enzymatic changes, cell volume should be considered also. Although it remains unclear as to the stimulus, or lack of stimulus, that triggers the rapid changes in muscle proteins in response to space flight, ground-based models of muscle atrophy suggest that the reduction in mechanical loading of muscle may be more important than the total amount of activation over a 24-hr period.

  3. Adaptation of rat jaw muscle fibers in postnatal development with a different food consistency: an immunohistochemical and electromyographic study.

    PubMed

    Kawai, Nobuhiko; Sano, Ryota; Korfage, Joannes A M; Nakamura, Saika; Kinouchi, Nao; Kawakami, Emi; Tanne, Kazuo; Langenbach, Geerling E J; Tanaka, Eiji

    2010-06-01

    The development of the craniofacial system occurs, among other reasons, as a response to functional needs. In particular, the deficiency of the proper masticatory stimulus affects the growth. The purpose of this study was to relate alterations of muscle activity during postnatal development to adaptational changes in the muscle fibers. Fourteen 21-day-old Wistar strain male rats were randomly divided into two groups and fed on either a solid (hard-diet group) or a powder (soft-diet group) diet for 63 days. A radio-telemetric device was implanted to record muscle activity continuously from the superficial masseter, anterior belly of digastric and anterior temporalis muscles. The degree of daily muscle use was quantified by the total duration of muscle activity per day (duty time), the total burst number and their average length exceeding specified levels of the peak activity (5, 20 and 50%). The fiber type composition of the muscles was examined by the myosin heavy chain content of fibers by means of immunohistochemical staining and their cross-sectional area was measured. All muscle fibers were identified as slow type I and fast type IIA, IIX or IIB (respectively, with increasing twitch contraction speed and fatigability). At lower activity levels (exceeding 5% of the peak activity), the duty time of the anterior belly of the digastric muscle was significantly higher in the soft-diet group than in the hard-diet group (P < 0.05). At higher activity levels (exceeding 20 and 50% of the peak activity), the duty time of the superficial masseter muscle in the soft-diet group was significantly lower than that in the hard-diet group (P < 0.05). There was no difference in the duty time of the anterior temporalis muscle at any muscle activity level. The percentage of type IIA fibers of the superficial masseter muscle in the soft-diet group was significantly lower than that in the hard-diet group (P < 0.01) and the opposite was true with regard to type IIB fibers (P < 0

  4. Isolation of satellite cells from single muscle fibers from young, aged, or dystrophic muscles.

    PubMed

    Di Foggia, Valentina; Robson, Lesley

    2012-01-01

    Skeletal muscle contains an identified resident stem cell population called the satellite cells. This cell is responsible for the majority of the postnatal growth and regenerative potential of skeletal muscle. Other cells do contribute to skeletal muscle regeneration and in cultures of minced whole muscle these cells are cultured along with the satellite cells and it is impossible to dissect out their contribution compared to the satellite cells. Therefore, a method to culture pure satellite cells has been developed to study the signaling pathways that control their proliferation and differentiation. In our studies into the role of the resident myogenic stem cells in regeneration, myopathic conditions, and aging, we have optimized the established techniques that already exist to isolate pure satellite cell cultures from single muscle fibers. We have successfully isolated satellite cells from young adults through to 24-month-old muscles and obtained populations of cells that we are studying for the signaling events that regulate their proliferative potential.

  5. Thin Filament-Reconstituted Skinned Muscle Fibers for the Study of Muscle Physiology

    PubMed Central

    Higuchi, Sayaka; Tsukasaki, Yoshikazu; Fukuda, Norio; Kurihara, Satoshi; Fujita, Hideaki

    2011-01-01

    We review the use of thin filament-reconstituted muscle fibers in the study of muscle physiology. Thin filament extraction and reconstitution protocol is a powerful technique to study the role of each component of the thin filament. It is also useful for studying the properties of genetically modified molecules such as actin and tropomyosin. We also review the combination of this protocol with sinusoidal analysis, which will provide a solid technique for determining the effect of regulatory proteins on actomyosin interaction and concomitant cross-bridge kinetics. We suggest that thin filament-reconstituted muscle fibers are an ideal system for studying muscle physiology especially when gene modifications of actin or tropomyosin are involved. PMID:22131807

  6. Muscle fibre types in the suprahyoid muscles of the rat

    PubMed Central

    COBOS, A. R.; SEGADE, L. A. G.; FUENTES, I.

    2001-01-01

    Five muscle fibre types (I, IIc, IIa, IIx and IIb) were found in the suprahyoid muscles (mylohyoid, geniohyoid, and the anterior and posterior bellies of the digastric) of the rat using immuno and enzyme histochemical techniques. More than 90% of fibres in the muscles examined were fast contracting fibres (types IIa, IIx and IIb). The geniohyoid and the anterior belly of the digastric had the greatest number of IIb fibres, whilst the mylohyoid was almost exclusively formed by aerobic fibres. The posterior belly of the digastric contained a greater percentage of aerobic fibres (83.4%) than the anterior belly (67.8%). With the exception of the geniohyoid, the percentage of type I and IIc fibres, which have slow myosin heavy chain (MHCβ), was relatively high and greater than has been previously reported in the jaw-closing muscles of the rat, such as the superficial masseter. The geniohyoid and mylohyoid exhibited a mosaic fibre type distribution, without any apparent regionalisation, although in the later MHCβ-containing fibres (types I and IIc) were primarily located in the rostral 2/3 region. In contrast, the anterior and posterior bellies of the digastric revealed a clear regionalisation. In the anterior belly of the digastric 2 regions were observed: both a central region, which was almost exclusively formed by aerobic fibres and where all of the type I and IIc fibres were located, and a peripheral region, where type IIb fibres predominated. The posterior belly of the digastric showed a deep aerobic region which was greater in size and where type I and IIc fibres were confined, and a superficial region, where primarily type IIx and IIb fibres were observed. PMID:11322721

  7. The effect of temperature on proliferation and differentiation of chicken skeletal muscle satellite cells isolated from different muscle types.

    PubMed

    Harding, Rachel L; Halevy, Orna; Yahav, Shlomo; Velleman, Sandra G

    2016-04-01

    Skeletal muscle satellite cells are a muscle stem cell population that mediate posthatch muscle growth and repair. Satellite cells respond differentially to environmental stimuli based upon their fiber-type of origin. The objective of this study was to determine how temperatures below and above the in vitro control of 38°C affected the proliferation and differentiation of satellite cells isolated from the chicken anaerobic pectoralis major (p. major) or mixed fiber biceps femoris (b.femoris) muscles. The satellite cells isolated from the p. major muscle were more sensitive to both cold and hot temperatures compared to the b.femoris satellite cells during both proliferation and differentiation. The expressions of myogenic regulatory transcription factors were also different between satellite cells from different fiber types. MyoD expression, which partially regulates proliferation, was generally expressed at higher levels in p. major satellite cells compared to the b.femoris satellite cells from 33 to 43°C during proliferation and differentiation. Similarly, myogenin expression, which is required for differentiation, was also expressed at higher levels in p. major satellite cells in response to both cold and hot temperatures during proliferation and differentiation than b. femoris satellite cells. These data demonstrate that satellite cells from the anaerobic p. major muscle are more sensitive than satellite cells from the aerobic b. femoris muscle to both hot and cold thermal stress during myogenic proliferation and differentiation.

  8. Defective Acetylcholine Receptor Subunit Switch Precedes Atrophy of Slow-Twitch Skeletal Muscle Fibers Lacking ERK1/2 Kinases in Soleus Muscle

    PubMed Central

    Wang, Shuo; Seaberg, Bonnie; Paez-Colasante, Ximena; Rimer, Mendell

    2016-01-01

    To test the role of extracellular-signal regulated kinases 1 and 2 (ERK1/2) in slow-twitch, type 1 skeletal muscle fibers, we studied the soleus muscle in mice genetically deficient for myofiber ERK1/2. Young adult mutant soleus was drastically wasted, with highly atrophied type 1 fibers, denervation at most synaptic sites, induction of “fetal” acetylcholine receptor gamma subunit (AChRγ), reduction of “adult” AChRε, and impaired mitochondrial biogenesis and function. In weanlings, fiber morphology and mitochondrial markers were mostly normal, yet AChRγ upregulation and AChRε downregulation were observed. Synaptic sites with fetal AChRs in weanling muscle were ~3% in control and ~40% in mutants, with most of the latter on type 1 fibers. These results suggest that: (1) ERK1/2 are critical for slow-twitch fiber growth; (2) a defective γ/ε-AChR subunit switch, preferentially at synapses on slow fibers, precedes wasting of mutant soleus; (3) denervation is likely to drive this wasting, and (4) the neuromuscular synapse is a primary subcellular target for muscle ERK1/2 function in vivo. PMID:27934942

  9. Latent mitochondrial DNA deletion mutations drive muscle fiber loss at old age.

    PubMed

    Herbst, Allen; Wanagat, Jonathan; Cheema, Nashwa; Widjaja, Kevin; McKenzie, Debbie; Aiken, Judd M

    2016-08-25

    With age, somatically derived mitochondrial DNA (mtDNA) deletion mutations arise in many tissues and species. In skeletal muscle, deletion mutations clonally accumulate along the length of individual fibers. At high intrafiber abundances, these mutations disrupt individual cell respiration and are linked to the activation of apoptosis, intrafiber atrophy, breakage, and necrosis, contributing to fiber loss. This sequence of molecular and cellular events suggests a putative mechanism for the permanent loss of muscle fibers with age. To test whether mtDNA deletion mutation accumulation is a significant contributor to the fiber loss observed in aging muscle, we pharmacologically induced deletion mutation accumulation. We observed a 1200% increase in mtDNA deletion mutation-containing electron transport chain-deficient muscle fibers, an 18% decrease in muscle fiber number and 22% worsening of muscle mass loss. These data affirm the hypothesized role for mtDNA deletion mutation in the etiology of muscle fiber loss at old age.

  10. Single-fiber expression and fiber-specific adaptability to short-term intense exercise training of Na+-K+-ATPase α- and β-isoforms in human skeletal muscle.

    PubMed

    Wyckelsma, V L; McKenna, M J; Serpiello, F R; Lamboley, C R; Aughey, R J; Stepto, N K; Bishop, D J; Murphy, R M

    2015-03-15

    The Na(+)-K(+)-ATPase (NKA) plays a key role in muscle excitability, but little is known in human skeletal muscle about fiber-type-specific differences in NKA isoform expression or adaptability. A vastus lateralis muscle biopsy was taken in 17 healthy young adults to contrast NKA isoform protein relative abundance between type I and IIa fibers. We further investigated muscle fiber-type-specific NKA adaptability in eight of these adults following 4-wk repeated-sprint exercise (RSE) training, comprising three sets of 5 × 4-s sprints, 3 days/wk. Single fibers were separated, and myosin heavy chain (I and IIa) and NKA (α1-3 and β1-3) isoform abundance were determined via Western blotting. All six NKA isoforms were expressed in both type I and IIa fibers. No differences between fiber types were found for α1-, α2-, α3-, β1-, or β3-isoform abundances. The NKA β2-isoform was 27% more abundant in type IIa than type I fibers (P < 0.05), with no other fiber-type-specific trends evident. RSE training increased β1 in type IIa fibers (pretraining 0.70 ± 0.25, posttraining 0.84 ± 0.24 arbitrary units, 42%, P < 0.05). No training effects were found for other NKA isoforms. Thus human skeletal muscle expresses all six NKA isoforms and not in a fiber-type-specific manner; this points to their different functional roles in skeletal muscle cells. Detection of elevated NKA β1 after RSE training demonstrates the sensitivity of the single-fiber Western blotting technique for fiber-type-specific intervention effects.

  11. Effect of endurance and/or strength training on muscle fiber size, oxidative capacity, and capillarity in hemodialysis patients.

    PubMed

    Lewis, Michael I; Fournier, Mario; Wang, Huiyuan; Storer, Thomas W; Casaburi, Richard; Kopple, Joel D

    2015-10-15

    We previously reported reduced limb muscle fiber succinate dehydrogenase (SDH) activity and capillarity density and increased cross-sectional areas (CSAs) of all fiber types in maintenance hemodialysis (MHD) patients compared with matched controls that may contribute to their effort intolerance and muscle weakness. This study evaluated whether endurance training (ET), strength training (ST), or their combination (EST) alters these metabolic and morphometric aberrations as a mechanism for functional improvement. Five groups were evaluated: 1) controls; 2) MHD/no training; 3) MHD/ET; 4) MHD/ST; and 5) MHD/EST. Training duration was 21.5 ± 0.7 wk. Vastus lateralis muscle biopsies were obtained after HD at baseline and at study end. Muscle fibers were classified immunohistochemically, and fiber CSAs were computed. Individual fiber SDH activity was determined by a microdensitometric assay. Capillaries were identified using antibodies against endothelial cells. Type I and IIA fiber CSAs decreased significantly (10%) with EST. In the ET group, SDH activity increased 16.3% in type IIA and 19.6% in type IIX fibers. Capillary density increased significantly by 28% in the EST group and 14.3% with ET. The number of capillaries surrounding individual fiber type increased significantly in EST and ET groups. Capillary-to-fiber ratio increased significantly by 11 and 9.6% in EST and ET groups, respectively. We conclude that increments in capillarity and possibly SDH activity in part underlie improvements in endurance of MHD patients posttraining. We speculate that improved specific force and/or neural adaptations to exercise underlie improvements in limb muscle strength of MHD patients.

  12. Effect of endurance and/or strength training on muscle fiber size, oxidative capacity, and capillarity in hemodialysis patients

    PubMed Central

    Fournier, Mario; Wang, Huiyuan; Storer, Thomas W.; Casaburi, Richard; Kopple, Joel D.

    2015-01-01

    We previously reported reduced limb muscle fiber succinate dehydrogenase (SDH) activity and capillarity density and increased cross-sectional areas (CSAs) of all fiber types in maintenance hemodialysis (MHD) patients compared with matched controls that may contribute to their effort intolerance and muscle weakness. This study evaluated whether endurance training (ET), strength training (ST), or their combination (EST) alters these metabolic and morphometric aberrations as a mechanism for functional improvement. Five groups were evaluated: 1) controls; 2) MHD/no training; 3) MHD/ET; 4) MHD/ST; and 5) MHD/EST. Training duration was 21.5 ± 0.7 wk. Vastus lateralis muscle biopsies were obtained after HD at baseline and at study end. Muscle fibers were classified immunohistochemically, and fiber CSAs were computed. Individual fiber SDH activity was determined by a microdensitometric assay. Capillaries were identified using antibodies against endothelial cells. Type I and IIA fiber CSAs decreased significantly (10%) with EST. In the ET group, SDH activity increased 16.3% in type IIA and 19.6% in type IIX fibers. Capillary density increased significantly by 28% in the EST group and 14.3% with ET. The number of capillaries surrounding individual fiber type increased significantly in EST and ET groups. Capillary-to-fiber ratio increased significantly by 11 and 9.6% in EST and ET groups, respectively. We conclude that increments in capillarity and possibly SDH activity in part underlie improvements in endurance of MHD patients posttraining. We speculate that improved specific force and/or neural adaptations to exercise underlie improvements in limb muscle strength of MHD patients. PMID:26183484

  13. Effects of diltiazem on skinned skeletal muscle fibers of the African clawed toad.

    PubMed

    Ishizuka, T; Endo, M

    1983-02-01

    To examine the effects of diltiazem and its l-cis isomer (which possesses only a weak Ca++-antagonistic action) on the contractile system and the sarcoplasmic reticulum of skeletal muscle, we used skinned fibers isolated from iliofibularis muscle of the African clawed toad, Xenopus laevis. Diltiazem showed the following effects: an increase in the Ca++ sensitivity of the contractile system, a decrease in the maximal tension developed in a saturating concentration of Ca++, an inhibition of Ca++ uptake by the sarcoplasmic reticulum, an inhibition of Ca++ release from the sarcoplasmic reticulum by caffeine, and an increase in the Ca++ permeability of the sarcoplasmic reticulum membrane. The effects of the l-cis isomer were similar to those of diltiazem, and the potencies of the two substances were nearly equal, except with respect to the effect on the Ca++ release induced by caffeine: the l-cis isomer potentiated this type of Ca++ release. Diltiazem's effects on amphibian skinned skeletal muscle fibers may not be related qualitatively or quantitatively to the Ca++-antagonistic actions of the drug on mammalian cardiac and smooth muscles. The pharmacological spectrum of diltiazem on skinned skeletal muscle fibers is similar to that of some local anesthetics.

  14. A different role of angiotensin II type 1a receptor in the development and hypertrophy of plantaris muscle in mice.

    PubMed

    Zempo, Hirofumi; Suzuki, Jun-Ichi; Ogawa, Masahito; Watanabe, Ryo; Isobe, Mitsuaki

    2016-02-01

    The role of angiotensin II type 1 (AT1) receptors in muscle development and hypertrophy remains unclear. This study was designed to reveal the effects that a loss of AT1 receptors has on skeletal muscle development and hypertrophy in mice. Eight-week-old male AT1a receptor knockout (AT1a(-/-)) mice were used for this experiment. The plantaris muscle to body weight ratio, muscle fiber cross-sectional area, and number of muscle fibers of AT1a(-/-) mice was significantly greater than wild type (WT) mice in the non-intervention condition. Next, the functional overload (OL) model was used to induce plantaris muscle hypertrophy by surgically removing the two triceps muscles consisting of the calf, soleus, and gastrocnemius muscles in mice. After 14 days of OL intervention, the plantaris muscle weight, the amount of fiber, and the fiber area increased. However, the magnitude of the increment of plantaris weight was not different between the two strains. Agtr1a mRNA expression did not change after OL in WT muscle. Actually, the Agt mRNA expression level of WT-OL was lower than WT-Control (C) muscle. An atrophy-related gene, atrogin-1 mRNA expression levels of AT1a(-/-)-C, WT-OL, and AT1a(-/-)-OL muscle were lower than that of WT-C muscle. Our findings suggest that AT1 receptor contributes to plantaris muscle development via atrogin-1 in mice.

  15. Cytoplasm-to-myonucleus ratios and succinate dehydrogenase activities in adult rat slow and fast muscle fibers

    NASA Technical Reports Server (NTRS)

    Tseng, B. S.; Kasper, C. E.; Edgerton, V. R.

    1994-01-01

    The relationship between myonuclear number, cellular size, succinate dehydrogenase activity, and myosin type was examined in single fiber segments (n = 54; 9 +/- 3 mm long) mechanically dissected from soleus and plantaris muscles of adult rats. One end of each fiber segment was stained for DNA before quantitative photometric analysis of succinate dehydrogenase activity; the other end was double immunolabeled with fast and slow myosin heavy chain monoclonal antibodies. Mean +/- S.D. cytoplasmic volume/myonucleus ratio was higher in fast and slow plantaris fibers (112 +/- 69 vs. 34 +/- 21 x 10(3) microns3) than fast and slow soleus fibers (40 +/- 20 vs. 30 +/- 14 x 10(3) microns3), respectively. Slow fibers always had small volumes/myonucleus, regardless of fiber diameter, succinate dehydrogenase activity, or muscle of origin. In contrast, smaller diameter (< 70 microns) fast soleus and plantaris fibers with high succinate dehydrogenase activity appeared to have low volumes/myonucleus while larger diameter (> 70 microns) fast fibers with low succinate dehydrogenase activity always had large volume/myonucleus. Slow soleus fibers had significantly greater numbers of myonuclei/mm than did either fast soleus or fast plantaris fibers (116 +/- 51 vs. 55 +/- 22 and 44 +/- 23), respectively. These data suggest that the myonuclear domain is more limited in slow than fast fibers and in the fibers with a high, compared to a low, oxidative metabolic capability.

  16. Differential epigenetic modifications of histones at the myosin heavy chain genes in fast and slow skeletal muscle fibers and in response to muscle unloading.

    PubMed

    Pandorf, Clay E; Haddad, Fadia; Wright, Carola; Bodell, Paul W; Baldwin, Kenneth M

    2009-07-01

    Recent advances in chromatin biology have enhanced our understanding of gene regulation. It is now widely appreciated that gene regulation is dependent upon post-translational modifications to the histones which package genes in the nucleus of cells. Active genes are known to be associated with acetylation of histones (H3ac) and trimethylation of lysine 4 in histone H3 (H3K4me3). Using chromatin immunoprecipitation (ChIP), we examined histone modifications at the myosin heavy chain (MHC) genes expressed in fast vs. slow fiber-type skeletal muscle, and in a model of muscle unloading, which results in a shift to fast MHC gene expression in slow muscles. Both H3ac and H3K4me3 varied directly with the transcriptional activity of the MHC genes in fast fiber-type plantaris and slow fiber-type soleus. During MHC transitions with muscle unloading, histone H3 at the type I MHC becomes de-acetylated in correspondence with down-regulation of that gene, while upregulation of the fast type IIx and IIb MHCs occurs in conjunction with enhanced H3ac in those MHCs. Enrichment of H3K4me3 is also increased at the type IIx and IIb MHCs when these genes are induced with muscle unloading. Downregulation of IIa MHC, however, was not associated with corresponding loss of H3ac or H3K4me3. These observations demonstrate the feasibility of using the ChIP assay to understand the native chromatin environment in adult skeletal muscle, and also suggest that the transcriptional state of types I, IIx and IIb MHC genes are sensitive to histone modifications both in different muscle fiber-types and in response to altered loading states.

  17. Functional pools of oxidative and glycolytic fibers in human muscle observed by /sup 31/P magnetic resonance spectroscopy during exercise

    SciTech Connect

    Park, J.H.; Brown, R.L.; Park, C.R.; McCully, K.; Cohn, M.; Haselgrove, J.; Chance, B.

    1987-12-01

    Quantitative probing of heterogeneous regions in muscle is feasible with phosphorus-31 magnetic resonance spectroscopy because of the differentiation of metabolic patterns of glycolytic and oxidative fibers. A differential recruitment of oxidative and glycolytic fibers during exercise was demonstrated in 4 of 10 untrained young men by following changes in phosphate metabolites. Concentrations of inorganic phosphate (P/sub i/), phosphocreatine, and ATP were estimated in the wrist flexor muscles of the forearm at rest, during two cycles of three grades of exercise, and in recovery. At high work levels (40% of maximum strength), two distinct P/sub i/ peaks were observed and identified with P/sub i/ pools at pH 6.9 and pH 5.9-6.4, respectively. These could be accounted for as follows. At the lowest level of work (using 20% of maximum strength), early recruitment primarily of oxidative (type I) and possibly some intermediate (type IIA) muscle fibers occurs with relatively little net lactate production and consequently little decrease in pH. At higher work loads, however, primarily glycolytic (type IIB) muscle fibers are recruited, which have relatively high net lactate production and therefore generate a second pool of P/sub i/ at low pH. These observations indicated exhaustion of glycolytic type IIB fibers, removal of lactate by high local blood flow, and sustained contractions largely by oxidative type I and IIA fibers. A functional differentiation of fiber types could also be demonstrated during recovery if exercise was stopped while two pools of P/sub i/ were still apparent. The potential of magnetic resonance spectroscopy to characterize oxidative and glycolytic fibers, predict capacity for aerobic performance, and signal the presence of muscle pathology is discussed.

  18. Memristive Model of the Barnacle Giant Muscle Fibers

    NASA Astrophysics Data System (ADS)

    Sah, Maheshwar Pd.; Kim, Hyongsuk; Eroglu, Abdullah; Chua, Leon

    The generation of action potentials (oscillations) in biological systems is a complex, yet poorly understood nonlinear dynamical phenomenon involving ions. This paper reveals that the time-varying calcium ion and the time-varying potassium ion, which are essential for generating action potentials in Barnacle giant muscle fibers are in fact generic memristors in the perspective of electrical circuit theory. We will show that these two ions exhibit all the fingerprints of memristors from the equations of the Morris-Lecar model of the Barnacle giant muscle fibers. This paper also gives a textbook reference to understand the difference between memristor and nonlinear resistor via analysis of the potassium ion-channel memristor and calcium ion-channel nonlinear resistor. We will also present a comprehensive in-depth analysis of the generation of action potentials (oscillations) in memristive Morris-Lecar model using small-signal circuit model and the Hopf bifurcation theorem.

  19. Imaging of calcium transients in skeletal muscle fibers.

    PubMed Central

    Vergara, J; DiFranco, M; Compagnon, D; Suarez-Isla, B A

    1991-01-01

    Epifluorescence images of Ca2+ transients elicited by electrical stimulation of single skeletal muscle fibers were studied with fast imaging techniques that take advantage of the large fluorescence signals emitted at relatively long wavelengths by the dyes fluo-3 and rhod-2 in response to binding of Ca2+ ions, and of the suitable features of a commercially available CCD video camera. The localized release of Ca2+ in response to microinjection of InsP3 was also monitored to demonstrate the adequate space and time resolutions of the imaging system. The time resolution of the imager system, although limited to the standard video frequency response, still proved to be adequate to investigate the fast Ca2+ release process in skeletal muscle fibers at low temperatures. Images FIGURE 4 FIGURE 5 FIGURE 6 PMID:2015378

  20. Skeletal muscle fibre types in the dog.

    PubMed Central

    Latorre, R; Gil, F; Vázquez, J M; Moreno, F; Mascarello, F; Ramirez, G

    1993-01-01

    Using a variety of histochemical methods we have investigated the mATPase reaction of skeletal muscle fibres in the dog. Types I, IIA, IIDog (peculiar to the dog) and IIC fibres were identified. The results reveal that the interpretation of the fibre type composition depends on the methods used. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8226288

  1. Egr3-dependent muscle spindle stretch receptor intrafusal muscle fiber differentiation and fusimotor innervation homeostasis.

    PubMed

    Oliveira Fernandes, Michelle; Tourtellotte, Warren G

    2015-04-08

    Muscle stretch proprioceptors (muscle spindles) are required for stretch reflexes and locomotor control. Proprioception abnormalities are observed in many human neuropathies, but the mechanisms involved in establishing and maintaining muscle spindle innervation and function are still poorly understood. During skeletal muscle development, sensory (Ia-afferent) innervation induces contacted myotubes to transform into intrafusal muscle fibers that form the stretch receptor core. The transcriptional regulator Egr3 is induced in Ia-afferent contacted myotubes by Neuregulin1 (Nrg1)/ErbB receptor signaling and it has an essential role in spindle morphogenesis and function. Because Egr3 is widely expressed during development and has a pleiotropic function, whether Egr3 functions primarily in skeletal muscle, Ia-afferent neurons, or in Schwann cells that myelinate Ia-afferent axons remains unresolved. In the present studies, cell-specific ablation of Egr3 in mice showed that it has a skeletal muscle autonomous function in stretch receptor development. Moreover, using genetic tracing, we found that Ia-afferent contacted Egr3-deficient myotubes were induced in normal numbers, but their development was blocked to generate one to two shortened fibers that failed to express some characteristic myosin heavy chain (MyHC) proteins. These "spindle remnants" persisted into adulthood, remained innervated by Ia-afferents, and expressed neurotrophin3 (NT3), which is required for Ia-afferent neuron survival. However, they were not innervated by fusimotor axons and they did not express glial derived neurotrophic factor (GDNF), which is essential for fusimotor neuron survival. These results demonstrate that Egr3 has an essential role in regulating gene expression that promotes normal intrafusal muscle fiber differentiation and fusimotor innervation homeostasis.

  2. Endothermic force generation in fast and slow mammalian (rabbit) muscle fibers.

    PubMed Central

    Ranatunga, K W

    1996-01-01

    Isometric tension responses to rapid temperature jumps (T-jumps) of 3-7 degrees C were examined in single skinned fibers isolated from rabbit psoas (fast) and soleus (slow) muscles. T-jumps were induced by an infrared laser pulse (wavelength 1.32 microns, pulse duration 0.2 ms) obtained from a Nd-YAG laser, which heated the fiber and bathing buffer solution in a 50-microliter trough. After a T-jump, the temperature near the fiber remained constant for approximately 0.5 s, and the temperature could be clamped for longer periods by means of Peltier units assembled on the back trough wall. A T-jump produced a step decrease in tension in both fast and slow muscle fibers in rigor, indicating thermal expansion. In maximally Ca-activated (pCa approximately 4) fibers, the increase of steady tension with heating (3-35 degrees C) was approximately sigmoidal, and a T-jump at any temperature induced a more complex tension transient than in rigor fibers. An initial (small amplitude) step decrease in tension followed by a rapid recovery (tau(1); see Davis and Harrington, 1993) was seen in some records from both fiber types, which presumably was an indirect consequence of thermal expansion. The net rise in tension after a T-jump was biexponential, and its time course was characteristically different in the two fibers. At approximately 12 degrees C the reciprocal time constants for the two exponential components (tau(2) and tau(3), respectively, were approximately 70.s(-1) and approximately 15.s(-1) in fast fibers and approximately 20.s(-1) and approximately 3.s(-1) in slow fibers. In both fibers, tau(2) ("endothermic force regeneration") became faster with an increase in temperature. Furthermore, tau(3) was temperature sensitive in slow fibers but not in fast fibers. The results are compared and contrasted with previous findings from T-jump experiments on fast fibers. It is observed that the fast/slow fiber difference in the rate of endothermic force generation (three- to

  3. Electrotonic Interaction between Muscle Fibers in the Rabbit Ventricle

    PubMed Central

    Tille, J.

    1966-01-01

    Transmembrane potentials were recorded simultaneously from pairs of ventricular fibers in an isolated, regularly beating preparation. A double-barrelled microelectrode was used to record the potentials from, and to polarize, one fiber. A single microelectrode was used to record from a distant fiber. The existence of two systems of fibers, termed P and V, was confirmed. Histological evidence for the existence of two types of fibers is also presented. Electrotonic current spread was observed within both systems, electrotonic interaction between the two systems was rare and always weak. In the case of those pairs of fibers showing electrotonic interaction, the distance for an e-fold decrease in magnitude of the electrotonic potentials was found to be from 300 to 600 µ in P fibers and from 100 to 300 µ in V fibers. However, no electrotonic interaction could be observed in the majority of V fiber pairs. Moreover, the magnitude of the electrotonic potential did not decay monotonically with distance in any one direction. It is concluded that the rabbit ventricle cannot be regarded as a single freely interconnected syncytium. PMID:5971027

  4. Fluctuations in tension during contraction of single muscle fibers.

    PubMed Central

    Borejdo, J; Morales, M F

    1977-01-01

    We have searched for fluctuations in the steady-state tension developed by stimulated single muscle fibers. Such tension "noise" is expected to be present as a result of the statistical fluctuations in the number and/or state of myosin cross-bridges interacting with thin filament sites at any time. A sensitive electro-optical tension transducer capable of resolving the expected fluctuations in magnitude and frequency was constructed to search for the fluctuations. The noise was analyzed by computing the power spectra and amplitude of stochastic fluctuations in the photomultiplier counting rate, which was made proportional to muscle force. The optical system and electronic instrumentation together with the minicomputer software are described. Tensions were measured in single skinned glycerinated rabbit psoas muscle fibers in rigor and during contraction and relaxation. The results indicate the presence of fluctuations in contracting muscles and a complete absence of tension noise in eith rigor or relaxation. Also, a numerical method was developed to simulate the power spectra and amplitude of fluctuations, given the rate constants for association and dissociation of the cross-bridges and actin. The simulated power spectra and the frequency distributions observed experimentally are similar. PMID:922123

  5. The human tongue slows down to speak: muscle fibers of the human tongue.

    PubMed

    Sanders, Ira; Mu, Liancai; Amirali, Asif; Su, Hungxi; Sobotka, Stanislaw

    2013-10-01

    Little is known about the specializations of human tongue muscles. In this study, myofibrillar adenosine triphosphatase (mATPase) histochemical staining was used to study the percentage and distribution of slow twitch muscle fibers (slow MFs) within tongue muscles of four neurologically normal human adults and specimens from a 2-year-old human, a newborn human, an adult with idiopathic Parkinson's disease (IPD), and a macaque monkey. The average percentage of slow MFs in adult and the 2-year-old muscle specimens was 54%, the IPD was 45%, while the neonatal human (32%) and macaque monkey (28%) had markedly fewer slow MFs. In contrast, the tongue muscles of the rat and cat have been reported to have no slow MFs. There was a marked spatial gradient in the distribution of slow MFs with the highest percentages found medially and posteriorly. Normal adult tongue muscles were found to have a variety of uniquely specialized features including MF-type grouping (usually found in neuromuscular disorders), large amounts of loose connective tissue, and short branching MFs. In summary, normal adult human tongue muscles have by far the highest proportion of slow MFs of any mammalian tongue studied to date. Moreover, adult human tongue muscles have multiple unique anatomic features. As the tongue shape changes that are seen during speech articulation are unique to humans, we hypothesize that the large proportion of slow MFs and the anatomical specializations observed in the adult human tongue have evolved to perform these movements.

  6. Single fiber analyses of glycogen-related proteins reveal their differential association with glycogen in rat skeletal muscle.

    PubMed

    Murphy, Robyn M; Xu, Hongyang; Latchman, Heidy; Larkins, Noni T; Gooley, Paul R; Stapleton, David I

    2012-12-01

    To understand how glycogen affects skeletal muscle physiology, we examined enzymes essential for muscle glycogen synthesis and degradation using single fibers from quiescent and stimulated rat skeletal muscle. Presenting a shift in paradigm, we show these proteins are differentially associated with glycogen granules. Protein diffusibility and/or abundance of glycogenin, glycogen branching enzyme (GBE), debranching enzyme (GDE), phosphorylase (GP), and synthase (GS) were examined in fibers isolated from rat fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscle. GDE and GP proteins were more abundant (~10- to 100-fold) in fibers from EDL compared with SOL muscle. GS and glycogenin proteins were similar between muscles while GBE had an approximately fourfold greater abundance in SOL muscle. Mechanically skinned fibers exposed to physiological buffer for 10 min showed ~70% total pools of GBE and GP were diffusible (nonbound), whereas GDE and GS were considerably less diffusible. Intense in vitro stimulation, sufficient to elicit a ~50% decrease in intracellular glycogen, increased diffusibility of GDE, GP, and GS (~15-60%) and decreased GBE diffusibility (~20%). Amylase treatment, which breaks α-1,4 linkages of glycogen, indicated differential diffusibilities and hence glycogen associations of GDE and GS. Membrane solubilization (1% Triton-X-100) allowed a small additional amount of GDE and GS to diffuse from fibers, suggesting the majority of nonglycogen-associated GDE/GS is associated with myofibrillar/contractile network of muscle rather than membranes. Given differences in enzymes required for glycogen metabolism, the current findings suggest glycogen particles have fiber-type-dependent structures. The greater catabolic potential of glycogen breakdown in fast-twitch fibers may account for different contraction induced rates of glycogen utilization.

  7. Muscle Fiber Characteristics, Satellite Cells and Soccer Performance in Young Athletes

    PubMed Central

    Metaxas, Thomas I.; Mandroukas, Athanasios; Vamvakoudis, Efstratios; Kotoglou, Kostas; Ekblom, Björn; Mandroukas, Konstantinos

    2014-01-01

    This study is aimed to examine the muscle fiber type, composition and satellite cells in young male soccer players and to correlate them to cardiorespiratory indices and muscle strength. The participants formed three Groups: Group A (n = 13), 11.2 ± 0.4yrs, Group B (n=10), 13.1 ± 0.5yrs and Group C (n = 9), 15.2 ± 0.6yrs. Muscle biopsies were obtained from the vastus lateralis. Peak torque values of the quadriceps and hamstrings were recorded and VO2max was measured on the treadmill. Group C had lower type I percentage distribution compared to A by 21.3% (p < 0.01), while the type IIA relative percentage was higher by 18.1% and 18.4% than in Groups A and B (p < 0.05). Groups B and C had higher cross-sectional area (CSA) values in all fiber types than in Group A (0.05 < p < 0.001). The number of satellite cells did not differ between the groups. Groups B and C had higher peak torque at all angular velocities and absolute VO2max in terms of ml·min-1 than Group A (0.05 < p < 0.001). It is concluded that the increased percentage of type IIA muscle fibers noticed in Group C in comparison to the Groups A and B should be mainly attributed to the different workload exercise and training programs. The alteration of myosin heavy chain (MHC) isoforms composition even in children is an important mechanism for skeletal muscle characteristics. Finally, CSA, isokinetic muscle strength and VO2max values seems to be expressed according to age. Key Points Fifteen years old soccer players have higher IIA percentage distribution than the younger players by approximately 18%. The age and the training status play a crucial role in muscle fibers co-expression. Specific training in young athletes seems to alter significantly the muscular metabolic profile. PMID:25177173

  8. Effects of electrical stimulation on histochemical muscle fiber staining, quality, and composition of camel and cattle Longissimus thoracis muscles.

    PubMed

    Kadim, I T; Mahgoub, O; Al-Marzooqi, W; Khalaf, S K; Mansour, M H; Al-Sinani, S S H; Al-Amri, I S

    2009-01-01

    The effects of electrical stimulation on muscle fiber type, meat quality, and composition of Longissimus thoracis muscles from one-humped camels and Dofari Omani cattle of a comparable age range were investigated. A low-voltage electrical stimulation with 90 V, 14 Hz (pulse of 7.5-millisecond duration every 70 milliseconds) 20 min postmortem was applied. Samples from the left muscle were collected from 20 (2 to 3 y) camels and 24 cattle (1 to 3 y). For chemical composition, muscle samples were dried in a freeze dryer, and then ground to determine moisture, protein, fat, and ash. Macro- and micro-minerals were determined using an Inductively Coupled Plasma Emission Spectrometer. Quality characteristics of the meat were evaluated using shear force value, pH, sarcomere, myofibrillar fragmentation index, expressed juice, cooking loss percent, and CIE L*, a*, b* color values. Electrical stimulation resulted in a significantly (P < 0.05) more rapid pH fall in the muscle during the first 24 h after slaughter in both species. Muscles from electrically stimulated carcasses had significantly (P < 0.05) lower ultimate pH, longer sarcomere, and lower shear force values than those from nonstimulated carcasses. Lightness (L*), myofibrillar fragmentation, and expressed juice were significantly (P < 0.05) higher for stimulated than for nonstimulated muscles. Muscles of camels had significantly (P < 0.05) higher expressed juice, cooking loss percent, redness color (a*), and lower fat, Mg, K, and P than those from cattle. Electrical stimulation improved quality characteristics of meat from both species. This indicates that meat quality of local camel and cattle can be improved by electrical stimulation and consequently improves their acceptability to consumers and better marketability.

  9. Gas7-Deficient Mouse Reveals Roles in Motor Function and Muscle Fiber Composition during Aging

    PubMed Central

    Huang, Bo-Tsang; Chang, Pu-Yuan; Su, Ching-Hua; Chao, Chuck C.-K.; Lin-Chao, Sue

    2012-01-01

    Background Growth arrest-specific gene 7 (Gas7) has previously been shown to be involved in neurite outgrowth in vitro; however, its actual role has yet to be determined. To investigate the physiological function of Gas7 in vivo, here we generated a Gas7-deficient mouse strain with a labile Gas7 mutant protein whose functions are similar to wild-type Gas7. Methodology/Principal Findings Our data show that aged Gas7-deficient mice have motor activity defects due to decreases in the number of spinal motor neurons and in muscle strength, of which the latter may be caused by changes in muscle fiber composition as shown in the soleus. In cross sections of the soleus of Gas7-deficient mice, gross morphological features and levels of myosin heavy chain I (MHC I) and MHC II markers revealed significantly fewer fast fibers. In addition, we found that nerve terminal sprouting, which may be associated with slow and fast muscle fiber composition, was considerably reduced at neuromuscular junctions (NMJ) during aging. Conclusions/Significance These findings indicate that Gas7 is involved in motor neuron function associated with muscle strength maintenance. PMID:22662195

  10. Relationship between innervation zone width and mean muscle fiber conduction velocity during a sustained isometric contraction

    PubMed Central

    Ye, X.; Beck, T.W.; Wages, N.P.

    2015-01-01

    Objectives: To examine the relationship between the biceps brachii muscle innervation zone (IZ) width and the mean muscle fiber conduction velocity (MFCV) during a sustained isometric contraction. Methods: Fifteen healthy men performed a sustained isometric elbow flexion exercise at their 60% maximal voluntary contraction (MVC) until they could not maintain the target force. Mean MFCV was estimated through multichannel surface electromyographic recordings from a linear electrode array. Before exercise, IZ width was quantified. Separate non-parametric one-way analyses of variance (ANOVAs) were used to examine whether there was a difference in each mean MFCV variable among groups with different IZ width. In addition, separate bivariate correlations were also performed to examine the relationships between the IZ width and the mean MFCV variables during the fatiguing exercise. Results: There was a significant difference in the percent decline of mean MFCV (%ΔMFCV) among groups with different IZ width (χ2 (3)=11.571, p=0.009). In addition, there was also a significant positive relationship between the IZ width and the %ΔMFCV (Kendall’s tau= 0.807; p<0.001). Conclusions: We believe that such relationship is likely influenced by both muscle fiber size and the muscle fiber type composition. PMID:25730657

  11. Reptilian skeletal muscle: contractile properties of identified, single fast-twitch and slow fibers from the lizard Dipsosaurus dorsalis.

    PubMed

    Gleeson, T T; Johnston, I A

    1987-06-01

    Contractile properties and innervation patterns were determined in identified single fibers from the iliofibularis muscle of the desert iguana, Dipsosaurus dorsalis. Single fibers from both the red and white regions of the iliofibularis muscle were dissected along their length under oil and a portion was mounted on transducers for determination of maximum isometric tension (Po) and unloaded shortening velocity (Vmax) using the slack test method. Fibers were chemically skinned and activated by high Ca++. The remaining portion of the muscle fiber was mounted on a glass slide and histochemically treated to demonstrate myosin ATPase activity. Fibers studied functionally could therefore be classified as fast or slow according to their myosin ATPase activity, and they could also be classified metabolically according to the region of the muscle from which they were dissected. Fast-twitch glycolytic (FG) fibers from the white region and fast-twitch oxidative, glycolytic (FOG) and slow fibers from the red region had shortening velocities at 25 degrees C of 7.5, 4.4, and 1.5 l X s-1, respectively. Po did not differ in the three fiber types, averaging 279 kN X m-2. In a second experiment, 10 microns sections were examined every 30 microns through the proximal-most 7.5 mm of the iliofibularis muscle for motor endplates. Sections were stained to demonstrate regions of acetylcholinesterase activity. Fibers with visible endplates were classified in serial sections by histochemical treatment for myosin ATPase and succinic dehydrogenase. All slow fibers examined (n = 22) exhibited multiple endplates, averaging one every 725 microns.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Halothane cooling contractures of skinned mammalian muscle fibers.

    PubMed

    Sudo, R T; Zapata-Sudo, G; Suarez-Kurtz, G

    1990-11-01

    The effects of halothane or cooling on Ca2(+)-activated tensions and on the uptake and release of Ca2+ by the sarcoplasmic reticulum were investigated in chemically skinned fibers of the extensor digitorum longus muscle of adult rabbits. At 22 degrees C, halothane (greater than 0.46 mM) induced Ca2+ release from the SR of Ca2(+)-loaded skinned fibers that resulted in transient tensions. Higher concentrations of halothane (greater than 4.65 mM) reduced the steady-state accumulation of Ca2+ in the SR at 22 degrees C. Cooling (to less than 10 degrees C) elicited transient contractures (cooling-induced contractures [CC]) in Ca2(+)-loaded skinned fibers, despite the fact that the tensions elicited by adding Ca2+ to the bath were depressed at these low temperatures. The skinned fibers did not develop CCs at 12-16 degrees C. Halothane cooling contractures could be elicited at these temperatures by exposing the fibers to halothane concentrations that failed to elicit Ca2+ release at 22 degrees C. The halothane cooling contractures were blocked by procaine but not by lidocaine. It was concluded that these contractures resulted from a synergistic interaction between halothane and cooling that stimulates Ca2+ release from, and reduces Ca2+ uptake by, the sarcoplasmic reticulum.

  13. Calcium transients in asymmetrically activated skeletal muscle fibers.

    PubMed Central

    Trube, G; Lopez, J R; Taylor, S R

    1981-01-01

    Skeletal muscle fibers of the frog Rana temporaria were held just taut and stimulated transversely by unidirectional electrical fields. We observed the reversible effects of stimulus duration (0.1-100 ms) and strength on action potentials, intracellular Ca2+ transients (monitored by aequorin), and contractile force during fixed-end contractions. Long duration stimuli (e.g., 10 ms) induced a maintained depolarization on the cathodal side of a cell and a maintained hyperpolarization on its anodal side. The hyperpolarization of the side facing the anode prevented the action potential from reaching mechanical threshold during strong stimuli. Variation of the duration or strength of a stimulus changed the luminescent response from a fiber injected with aequorin. Thus, the intracellular Ca2+ released during excitation-contraction coupling could be changed by the stimulus parameters. Prolongation of a stimulus at field strengths above 1.1 x rheobase decreased the amplitude of aequorin signals and the force of contractions. The decreases in aequorin and force signals from a given fiber paralleled one another and depended on the stimulus strength, but not on the stimulus polarity. These changes were completely reversible for stimulus strengths up to at least 4.2 x rheobase. The graded decreases in membrane depolarization, aequorin signals, and contractile force were correlated with the previously described folding of myofibrils in fibers allowed to shorten in response to the application of a long duration stimulus. The changes in aequorin signals and force suggest an absence of myofilament activation by Ca2+ in the section of the fiber closest to the anode. The results imply that injected aequorin distributes circumferentially in frog muscle with a coefficient of at least 10(-7) cm2/s, which is not remarkably different from the previously measured coefficient of 5 x 10(-8) cm2/s for its diffusion lengthwise. PMID:6976801

  14. Segmental fibre type composition of the rat iliopsoas muscle.

    PubMed

    Vlahovic, Hrvoje; Bazdaric, Ksenija; Marijancic, Verner; Soic-Vranic, Tamara; Malnar, Daniela; Arbanas, Juraj

    2017-01-18

    The iliopsoas of the rat is composed of two muscles - the psoas major muscle and the iliacus muscle. The psoas major muscle arises from all the lumbar vertebrae and the iliacus muscle from the fifth and sixth lumbar vertebrae and ilium. Their common insertion point is the lesser trochanter of the femur, and their common action is the lateral rotation of the femur and flexion of the hip joint. Unlike humans, the rat is a quadruped and only occasionally rises up on its hind legs. Therefore, it is expected that the fibre type composition of the rat iliopsoas muscle will be different than that of humans. The iliopsoas muscle of the rat is generally considered to be a fast muscle. However, previous studies of the fibre type composition of the rat psoas muscle showed different results. Moreover, very little is known about the composition of the rat iliacus muscle. The aim of our study was to examine the fibre type composition of the rat iliopsoas muscle in order to better understand the complex function of the listed muscle. The psoas major muscle was examined segmentally at four different levels of its origin. Type I, IIA, IIB and IIX muscle fibres were typed using monoclonal antibodies for myosin heavy chain identification. The percentage of muscle fibre types and muscle fibre cross-sectional areas were calculated. In our study we showed that in the rat iliopsoas muscle both the iliacus and the psoas major muscles had a predominance of fast muscle fibre types, with the highest percentage of the fastest IIB muscle fibres. Also, the IIB muscle fibres showed the largest cross-sectional area (CSA) in both muscles. As well, the psoas major muscle showed segmental differences of fibre type composition. Our results showed changes in percentages, as well as the CSAs of muscle fibre types in cranio-caudal direction. The most significant changes were visible in type IIB muscle fibres, where there was a decrease of percentages and the CSAs from the cranial towards the caudal part

  15. The Mode of Transverse Spread of Contraction Initiated by Local Activation in Single Crayfish Muscle Fibers

    PubMed Central

    Sugi, Haruo; Ochi, Rikuo

    1967-01-01

    Isolated single crayfish muscle fibers were locally activated by applying negative current pulses to a pipette whose tip was in contact with the fiber surface. The contraction initiated by a moderate depolarization spread inwards in a graded manner according to the magnitude and duration of depolarization. Increase of the depolarized area increased the distance of the inward spread for a given amount of depolarization. If a large area of the surface membrane was depolarized with a large pipette for a sufficiently long time, the contraction spread not only inwards, but further transversely passing through the center of the fiber. Successive brief depolarizations given at an appropriate interval could produce contraction more effectively for a given amount of total current than did a prolonged depolarization. On the other hand, the contraction initiated by a strong negative current was observed to spread around the whole perimeter but not through the center of the fiber. Each type of local contraction always spread along the striation pattern and not longitudinally. Possible mechanisms of these responses are discussed in connection with the transverse tubular system of the muscle fibers. PMID:19873574

  16. Preparation of adult muscle fiber-associated stem/precursor cells.

    PubMed

    Conboy, Michael J; Conboy, Irina M

    2010-01-01

    In our studies of muscle regeneration we have developed, modified, and optimized techniques to isolate and study the stem and precursor cells to muscle tissue. Our goals have been to obtain for study muscle fibers in bulk, or the fiber-associated cells, separately from the other cells found in muscle. Using these techniques, myofiber-associated cells may be isolated from neonatal through adult muscle, from resting or from regenerating muscle, thus allowing one to investigate the cellular populations participating during the time course of these events. The protocol is applicable to any age and condition of muscle and may be adapted for other tissues.

  17. Alpine Skiing With total knee ArthroPlasty (ASWAP): metabolism, inflammation, and skeletal muscle fiber characteristics.

    PubMed

    Kristensen, M; Pötzelsberger, B; Scheiber, P; Bergdahl, A; Hansen, C N; Andersen, J L; Narici, M; Salvioli, S; Conte, M; Müller, E; Dela, F

    2015-08-01

    We investigated the effect of alpine skiing for 12 weeks on skeletal muscle characteristics and biomarkers of glucose homeostasis and cardiovascular risk factors. Twenty-three patients with a total knee arthroplasty (TKA) were studied 2.9 ± 0.9 years (mean ± SD) after the operation. Fourteen patients participated in the intervention group (IG) and nine in the control group (CG). Blood samples and muscle biopsies were obtained before (PRE) and 7.3 ± 0.8 days after (POST) the intervention, and blood samples again after a retention (RET) phase of 8 weeks. With skiing, glucose homeostasis improved in IG (decrease in fasting insulin, increase in muscle glycogen) but not in CG. Fiber type distribution and size, as well as capillary density and number of capillaries around the fibers (CAF), were not different between the operated and the non-operated leg in either group. The relative number of type I fibers increased with skiing in IG with no change in CG. Inflammatory biomarkers, plasma lipids, and mitochondrial proteins and activity did not change. Alpine skiing is metabolically beneficial and can be used as a training modality by elderly people with TKA.

  18. Absolute amounts and diffusibility of HSP72, HSP25, and αB-crystallin in fast- and slow-twitch skeletal muscle fibers of rat.

    PubMed

    Larkins, Noni T; Murphy, Robyn M; Lamb, Graham D

    2012-01-01

    Heat shock proteins (HSPs) are essential for normal cellular stress responses. Absolute amounts of HSP72, HSP25, and αB-crystallin in rat extensor digitorum longus (EDL) and soleus (SOL) muscle were ascertained by quantitative Western blotting to better understand their respective capabilities and limitations. HSP72 content of EDL and SOL muscle was only ∼1.1 and 4.6 μmol/kg wet wt, respectively, and HSP25 content approximately twofold greater (∼3.4 and ∼8.9 μmol/kg, respectively). αB-crystallin content of EDL muscle was ∼4.9 μmol/kg but in SOL muscle was ∼30-fold higher (∼140 μmol/kg). To examine fiber heterogeneity, HSP content was also assessed in individual fiber segments; every EDL type II fiber had less of each HSP than any SOL type I fiber, whereas the two SOL type II fibers examined were indistinguishable from the EDL type II fibers. Sarcolemma removal (fiber skinning) demonstrated that 10-20% of HSP25 and αB-crystallin was sarcolemma-associated in SOL fibers. HSP diffusibility was assessed from the extent and rate of diffusion out of skinned fiber segments. In unstressed SOL fibers, 70-90% of each HSP was readily diffusible, whereas ∼95% remained tightly bound in fibers from SOL muscles heated to 45°C. Membrane disruption with Triton X-100 allowed dispersion of HSP72 and sarco(endo)plasmic reticulum Ca(2+)-ATPase pumps but did not alter binding of HSP25 or αB-crystallin. The amount of HSP72 in unstressed EDL muscle is much less than the number of its putative binding sites, whereas SOL type I fibers contain large amounts of αB-crystallin, suggesting its importance in normal cellular function without upregulation.

  19. Identification of a Novel Slow-Muscle-Fiber Enhancer Binding Protein, MusTRD1

    PubMed Central

    O’Mahoney, John V.; Guven, Kim L.; Lin, Jia; Joya, Josephine E.; Robinson, C. Stephen; Wade, Robert P.; Hardeman, Edna C.

    1998-01-01

    The molecular mechanisms which are responsible for restricting skeletal muscle gene expression to specific fiber types, either slow or fast twitch, are unknown. As a first step toward defining the components which direct slow-fiber-specific gene expression, we identified the sequence elements of the human troponin I slow upstream enhancer (USE) that bind muscle nuclear proteins. These include an E-box, a MEF2 element, and two other elements, USE B1 and USE C1. In vivo analysis of a mutation that disrupts USE B1 binding activity suggested that the USE B1 element is essential for high-level expression in slow-twitch muscles. This mutation does not, however, abolish slow-fiber specificity. A similar analysis indicated that the USE C1 element may play only a minor role. We report the cloning of a novel human USE B1 binding protein, MusTRD1 (muscle TFII-I repeat domain-containing protein 1), which is expressed predominantly in skeletal muscle. Significantly, MusTRD1 contains two repeat domains which show remarkable homology to the six repeat domains of the recently cloned transcription factor TFII-I. Furthermore, both TFII-I and MusTRD1 bind to similar but distinct sequences, which happen to conform with the initiator (Inr) consensus sequence. Given the roles of MEF2 and basic helix-loop-helix (bHLH) proteins in muscle gene expression, the similarity of TFII-I and MusTRD1 is intriguing, as TFII-I is believed to coordinate the interaction of MADS-box proteins, bHLH proteins, and the general transcription machinery. PMID:9774679

  20. An improved vaseline gap voltage clamp for skeletal muscle fibers

    PubMed Central

    1976-01-01

    A Vaseline gap potentiometric recording and voltage clamp method is developed for frog skeletal muscle fibers. The method is based on the Frankenhaeuser-Dodge voltage clamp for myelinated nerve with modifications to improve the frequency response, to compensate for external series resistance, and to compensate for the complex impedance of the current-passing pathway. Fragments of single muscle fibers are plucked from the semitendinosus muscle and mounted while depolarized by a solution like CsF. After Vaseline seals are formed between fluid pools, the fiber ends are cut once again, the central region is rinsed with Ringer solution, and the feedback amplifiers are turned on. Errors in the potential and current records are assessed by direct measurements with microelectrodes. The passive properties of the preparation are simulated by the "disk" equivalent circuit for the transverse tubular system and the derived parameters are similar to previous measurements with microelectrodes. Action potentials at 5 degrees C are long because of the absence of delayed rectification. Their shape is approximately simulated by solving the disk model with sodium permeability in the surface and tubular membranes. Voltage clamp currents consist primarily of capacity currents and sodium currents. The peak inward sodium current density at 5 degrees C is 3.7 mA/cm2. At 5 degrees C the sodium currents are smoothly graded with increasing depolarization and free of notches suggesting good control of the surface membrane. At higher temperatures a small, late extra inward current appears for small depolarizations that has the properties expected for excitation in the transverse tubular system. Comparison of recorded currents with simulations shows that while the transverse tubular system has regenerative sodium currents, they are too small to make important errors in the total current recorded at the surface under voltage clamp at low temperature. The tubules are definitely not under voltage

  1. Electro-optical property of extremely stretched skinned muscle fibers.

    PubMed Central

    Umazume, Y; Fujime, S

    1975-01-01

    Skinned fibers of frog semitendinosus muscle could easily be stretched up to 8 mum or more in sarcomere length. Such extremely stretched fibers gave quite sharp optical diffraction patterns. The intensities of all observable diffraction lines were found to increase on application of electric field (10 similar to 100 V/cm) parallel to the fiber axis, provided that there was no overlap between thin and thick filaments. By use of a polarizing microscope, it was concluded that I-bands were mainly responsible for this intensity increase. By application of square pulses, the time course of the intensity increase and decay was followed. The analysis based on a simple model suggests: (a) Each thin filament has a permanent dipole movement and the movement directs from Z-bands to the free end of the thin filament. (b) The flexural rigidity of thin filaments is estimated to be similar to 3 with 10-17 dyn with cm-2. The present fibers will provide various applications in physiochemical studies of in vivo thin and thick filaments. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 8 FIGURE 9 FIGURE 10 PMID:1078630

  2. Ultrastructure of mouse striated muscle fibers following pravastatin administration.

    PubMed

    Bergman, Michael; Salman, Hertzel; Djaldetti, Meir; Alexandrova, Svetlana; Punsky, Igor; Bessler, Hanna

    2003-01-01

    To examine the effect of pravastatin administration on striated muscle ultrastructure, 10 BalbC mice were given pravastatin 40 mg/kg/day for 3 weeks. At the end of the study, blood was withdrawn for evaluation of the serum creatine phospho-kinase (CPK) level and the muscles of the hind legs, as well as the heart and liver of the animals were examined with a light and transmission electron microscope. After treatment with pravastatin the results showed a 101% increase in serum CPK level in comparison to untreated controls. Hematoxillin-eosin stained tissues of pravastatin treated mice did not show any abnormal findings. While the ultrastructure of the heart and liver of the treated animals appeared normal, the muscle fibers showed a marked alterations of the mitochondria, which were increased in size compared to those of the controls. The cristae were heavily damaged and even completely destructed, giving the mitochondria appearance of empty vacuoles. The findings are in favor of a specificity of pravastatin for striated muscles.

  3. Quantification of muscle fiber strain during in vivo repetitive stretch-shortening cycles.

    PubMed

    Butterfield, Timothy A; Herzog, Walter

    2005-08-01

    Muscles subjected to lengthening contractions exhibit evidence of subcellular disruption, arguably a result of fiber strain magnitude. Due to the difficulty associated with measuring fiber strains during lengthening contractions, fiber length estimates have been used to formulate relationships between the magnitude of injury and mechanical measures such as fiber strain. In such protocols, the series compliance is typically minimized by removing the distal tendon and/or preactivating the muscle. These in vitro and in situ experiments do not represent physiological contractions well where fiber strain and muscle strain may be disassociated; thus the mechanisms of in vivo muscle injury remain elusive. The purpose of this paper was to quantify fiber strains during lengthening contractions in vivo and assess the potential role of fiber strain in muscle injury following repetitive stretch-shortening cycles. Using intact New Zealand White rabbit dorsiflexors, fiber strain and joint torque were measured during 50 stretch-shortening cycles. We were able to show that fiber length changes are disassociated from muscle tendon unit length changes and that complex fiber dynamics during these cycles prevent easy estimates of fiber strains. In addition, fiber strains vary, depending on how they are defined, and vary from repetition to repetition, thereby further complicating the potential relationship between muscle injury and fiber strain. We conclude from this study that, during in vivo stretch-shortening cycles, the relationship between fiber strain and muscle injury is complex. This is due, in part, to temporal effects of repeated loading on fiber strain magnitude that may be explained by an increasing compliance of the contractile element as exercise progresses.

  4. In vivo simultaneous evaluations of sarcomere imaging and muscle fiber tension.

    PubMed

    Wu, Yi-Ning; Ren, Yupeng; Tsai, Liang-Ching; Gao, Fan; Zhang, Li-Qun

    2016-03-21

    Muscle fiber tension and sarcomere length play critical roles in regulating muscle functions and adaptations under pathological conditions. However, methods are lacking to quantify these two variables simultaneously in vivo. A novel force microscope was developed with the unique capabilities of estimating muscle fiber tension and acquiring sarcomere images simultaneously in vivo. The force microscope consisting of a custom microscopic imaging system and a force sensor was used to quantify in vivo sarcomere length, muscle fiber tension and stress of the tibialis cranialis muscle at plantar-flexed and dorsi-flexed positions from 11 rat hind limbs. Results showed that sarcomere images and fiber tension could be measured together in vivo with significantly higher muscle fiber tension and stress and longer sarcomere length at the plantar-flexed position when compared to their counterparts at the dorsi-flexed position. The fiber tension estimated using the force microscope had close agreement with the direct measurements of the fiber tension. The present force microscope with simultaneous characterizations of fiber tension and sarcomere imaging provides us a useful in vivo tool to investigate the roles of muscle tension in regulating sarcomere and muscle fiber functions under physiological and pathological conditions.

  5. Single muscle fiber adaptations to resistance training in old (>80 yr) men: evidence for limited skeletal muscle plasticity.

    PubMed

    Slivka, Dustin; Raue, Ulrika; Hollon, Chris; Minchev, Kiril; Trappe, Scott

    2008-07-01

    The purpose of this study was to investigate whole muscle and single muscle fiber adaptations in very old men in response to progressive resistance training (PRT). Six healthy independently living old men (82 +/- 1 yr; range 80-86 yr, 74 +/- 4 kg) resistance-trained the knee extensors (3 sets, 10 repetitions) at approximately 70% one repetition maximum 3 days/wk for 12 wk. Whole thigh muscle cross-sectional area (CSA) was assessed before and after PRT using computed tomography (CT). Muscle biopsies were obtained from the vastus lateralis before and after the PRT program. Isolated myosin heavy chain (MHC) I and IIa single muscle fibers (n = 267; 142 pre; 125 post) were studied for diameter, peak tension, shortening velocity, and power. An additional set of isolated single muscle fibers (n = 2,215; 1,202 pre; 1,013 post) was used to identify MHC distribution. One repetition maximum knee extensor strength increased (P < 0.05) 23 +/- 4 kg (56 +/- 4 to 79 +/- 7 kg; 41%). Muscle CSA increased (P < 0.05) 3 +/- 1 cm2 (120 +/- 7 to 123 +/- 7 cm2; 2.5%). Single muscle fiber contractile function and MHC distribution were unaltered with PRT. These data indicate limited muscle plasticity at the single-muscle fiber level with a resistance-training program among the very old. The minor increases in whole muscle CSA coupled with the static nature of the myocellular profile indicate that the strength gains were primarily neurological. These data contrast typical muscle responses to resistance training in young ( approximately 20 yr) and old ( approximately 70 yr) humans and indicate that the physiological regulation of muscle remodeling is adversely modified in the oldest old.

  6. How muscle fiber lengths and velocities affect muscle force generation as humans walk and run at different speeds

    PubMed Central

    Arnold, Edith M.; Hamner, Samuel R.; Seth, Ajay; Millard, Matthew; Delp, Scott L.

    2013-01-01

    SUMMARY The lengths and velocities of muscle fibers have a dramatic effect on muscle force generation. It is unknown, however, whether the lengths and velocities of lower limb muscle fibers substantially affect the ability of muscles to generate force during walking and running. We examined this issue by developing simulations of muscle–tendon dynamics to calculate the lengths and velocities of muscle fibers from electromyographic recordings of 11 lower limb muscles and kinematic measurements of the hip, knee and ankle made as five subjects walked at speeds of 1.0–1.75 m s−1 and ran at speeds of 2.0–5.0 m s−1. We analyzed the simulated fiber lengths, fiber velocities and forces to evaluate the influence of force–length and force–velocity properties on force generation at different walking and running speeds. The simulations revealed that force generation ability (i.e. the force generated per unit of activation) of eight of the 11 muscles was significantly affected by walking or running speed. Soleus force generation ability decreased with increasing walking speed, but the transition from walking to running increased the force generation ability by reducing fiber velocities. Our results demonstrate the influence of soleus muscle architecture on the walk-to-run transition and the effects of muscle–tendon compliance on the plantarflexors' ability to generate ankle moment and power. The study presents data that permit lower limb muscles to be studied in unprecedented detail by relating muscle fiber dynamics and force generation to the mechanical demands of walking and running. PMID:23470656

  7. Skeletal muscle fiber atrophy: altered thin filament density changes slow fiber force and shortening velocity.

    PubMed

    Riley, D A; Bain, J L W; Romatowski, J G; Fitts, R H

    2005-02-01

    Single skinned fibers from soleus and adductor longus (AL) muscles of weight-bearing control rats and rats after 14-day hindlimb suspension unloading (HSU) were studied physiologically and ultrastructurally to investigate how slow fibers increase shortening velocity (V0) without fast myosin. We hypothesized that unloading and shortening of soleus during HSU reduces densities of thin filaments, generating wider myofilament separations that increase V0 and decrease specific tension (kN/m2). During HSU, plantarflexion shortened soleus working length 23%. AL length was unchanged. Both muscles atrophied as shown by reductions in fiber cross-sectional area. For AL, the 60% atrophy accounted fully for the 58% decrease in absolute tension (mN). In the soleus, the 67% decline in absolute tension resulted from 58% atrophy plus a 17% reduction in specific tension. Soleus fibers exhibited a 25% reduction in thin filaments, whereas there was no change in AL thin filament density. Loss of thin filaments is consistent with reduced cross bridge formation, explaining the fall in specific tension. V0 increased 27% in soleus but was unchanged in AL. The V0 of control and HSU fibers was inversely correlated (R = -0.83) with thin filament density and directly correlated (R = 0.78) with thick-to-thin filament spacing distance in a nonlinear fashion. These data indicate that reduction in thin filament density contributes to an increased V0 in slow fibers. Osmotically compacting myofilaments with 5% dextran returned density, spacing, and specific tension and slowed V0 to near-control levels and provided evidence for myofilament spacing modulating tension and V0.

  8. Dimensions of calcium release domains in frog skeletal muscle fibers

    NASA Astrophysics Data System (ADS)

    Vergara, Julio L.; DiFranco, Marino; Novo, David

    2001-07-01

    The spatiotemporal properties of the Ca2+ release process in skeletal muscle fibers were determined using an improved confocal spot detection system. Muscle fibers were loaded with the low affinity fluorescent Ca2+ indicator OGB-5N and localized action potential-induced fluorescence signals were recorded from consecutive locations separated by 200 nm within a single sarcomere. Three-dimensional reconstructions on the Ca2+ transients illustrate the existence of domains of increased fluorescence around Ca2+ release sites in the neighborhood of the T-tubules. We estimated the dimensions of these domains by drawing isochronal curves ((delta) F/F vs. spot position) and fitting Gaussian profiles to them. It was found that the earliest detectable full-width-at-half- maximum of these profiles was 0.77 +/- 0.25 micrometers and increased rapidly with time to 1.4 +/- 0.2 micrometers at their peak (18 degree(s)C). A brief, but statistically significant delay of 0.8 +/- 0.42ms was observed between the onset of the fluorescent transients at the Z- and M-lines. Our results are compatible with the possibility that, in response to AP stimulation, Ca2+ is not released exclusively from the junctional region of the sarcoplasmic reticulum, but from a broader expanse of the triadic region.

  9. Effect of Resistance Training on Capillary Density Around Slow and Fast Twitch Muscle Fibers in Diabetic and Normal Rats

    PubMed Central

    Karimian, Jahangir; Khazaei, Majid; Shekarchizadeh, Parivash

    2015-01-01

    Background: It is well accepted that skeletal muscle conforms to exercise stimulus by increasing capillary density and angiogenesis, but there is less evidence regarding the effect of resistance training on capillary density in flexor hallucis longus (FHL) and soleus muscle. Objectives: In this study, we evaluated the effect of resistance training on capillary density around soleus and FHL muscles in type 1 diabetic rats. Materials and Methods: Thirty-six male rats were divided into four groups: (1) control; (2) diabetic; (3) diabetic trained and (4) control trained (n = 9 each). A Single intraperitoneal injection of Streptozotocin at a dose of 55 mg/kg was used for induction of diabetes. The rats in the trained group undertook one training session per day for 3 days/week. Training was done with the use of a 1 meter high ladder inclined at 80°. After 4 weeks, the plasma nitrite concentrations were measured. Capillary/fiber ratio was determined around soleus and FHL muscles by immunohistochemistry. Results: Plasma Nitric Oxide (NO) concentration was increased after resistance training in diabetic animals (P < 0.05). Capillary/fiber ratio around the soleus muscle of diabetic group was more than control rats. Resistance training did not alter capillary/fiber ratio in diabetic animals (1.00 ± 0.6 vs. 1.07 ± 0.07, respectively). Capillary/fiber ratio around FHL muscle was significantly different between diabetic and control and did not alter after exercise (diabetes: 1.1702 ± 0.09; diabetic trained: 1.1714 ± 0.08; control: 0.79 ± 0.08; control trained: 0.73 ± 0.03). There was a positive correlation between plasma NO concentration and capillary density in the soleus muscle (R2 = 0.65). Conclusions: Resistance training could not improve capillary/fiber ratio in soleus and FHL muscle of diabetic animals in spite of increase in some angiogenic factors including NO. PMID:26715966

  10. Mapping of intramuscular tenderness and muscle fiber orientation of muscles in the beef round.

    PubMed

    Senaratne, L S; Calkins, C R; de Mello, A S; Pokharel, S; Hinkle, J B

    2010-09-01

    Intramuscular tenderness variation and muscle fiber orientation of beef M. adductor femoris (AF), M. biceps femoris (BF), M. gracilis (GL), M. pectineus (PT), M. sartorius (SR), M. semimembranosus (SM), M. semitendinosus (SO), M. vastus intermedius (VI), M. vastus medialis (VM), and M. vastus lateralis (VL) were investigated. The USDA Choice boxed beef subprimals were purchased and aged for 14 d from boxed date. The AF, BF, GL, PT, SR, SM, SO, VI, VM, and VL (n = 10 each) were fabricated from subprimals. Crust-frozen AF, BF, SO, SM, and VL were cut into 2.54-cm steaks perpendicular to the long axis and grilled (71 degrees C). The PT, SR, VI, and VM were grilled (71 degrees C) as whole muscles, whereas the GL was grilled after cutting into anterior and posterior regions. Grilled muscles were cut into equal size sections perpendicular to long axis of muscles. Location-specific cores were prepared from each steak/section, and Warner-Bratzler shear force (WBSF) was measured. The muscle fiber orientations of BF, PT, and VI were bipennate, SR and SO were fusiform, and AD, SM, VL, GL, and VM were unipennate. The overall mean WBSF values for BF, SO, AF, SM, PT, SR, GL, VI, VM, and VL were 5.62, 4.86, 4.18, 4.90, 3.76, 4.44, 4.75, 4.78, 4.24, and 6.53 kg, respectively. Based on WBSF values, PT was tender, BF and VL were tough, and VM, VI, SM, GL SR, AF, and SO were intermediate. The first 2 proximal steaks of long head BF were more tender than the rest (P < 0.05). In the SO, the tenderness decreased from the middle of the muscle to both ends (P < 0.05). The anterior sides of the long head BF and SO were tougher than their posterior sides (P < 0.05).The first 4 steaks of the SM were more tender than the rest of the muscle (P < 0.05). There was a significant tenderness increment from the middle of the AF and SR to both ends of each muscle (P < 0.05). The medial side of the VI was more tender than its lateral side (P < 0.05). The VM had its smallest shear force value at the

  11. Distinctive genes determine different intramuscular fat and muscle fiber ratios of the longissimus dorsi muscles in Jinhua and landrace pigs.

    PubMed

    Wu, Ting; Zhang, Zhenhai; Yuan, Zhangqin; Lo, Li Jan; Chen, Jun; Wang, Yizhen; Peng, Jinrong

    2013-01-01

    Meat quality is determined by properties such as carcass color, tenderness and drip loss. These properties are closely associated with meat composition, which includes the types of muscle fiber and content of intramuscular fat (IMF). Muscle fibers are the main contributors to meat mass, while IMF not only contributes to the sensory properties but also to the plethora of physical, chemical and technological properties of meat. However, little is known about the molecular mechanisms that determine meat composition in different pig breeds. In this report we show that Jinhua pigs, a Chinese breed, contains much higher levels of IMF than do Landrace pigs, a Danish breed. We analyzed global gene expression profiles in the longissimus dorsi muscles in Jinhua and Landrace breeds at the ages of 30, 90 and 150 days. Cross-comparison analysis revealed that genes that regulate fatty acid biosynthesis (e.g., fatty acid synthase and stearoyl-CoA desaturase) are expressed at higher levels in Jinhua pigs whereas those that regulate myogenesis (e.g., myogenic factor 6 and forkhead box O1) are expressed at higher levels in Landrace pigs. Among those genes which are highly expressed in Jinhua pigs at 90 days (d90), we identified a novel gene porcine FLJ36031 (pFLJ), which functions as a positive regulator of fat deposition in cultured intramuscular adipocytes. In summary, our data showed that the up-regulation of fatty acid biosynthesis regulatory genes such as pFLJ and myogenesis inhibitory genes such as myostatin in the longissimus dorsi muscles of Jinhua pigs could explain why this local breed produces meat with high levels of IMF.

  12. Localized nuclear and perinuclear Ca2+ signals in intact mouse skeletal muscle fibers

    PubMed Central

    Georgiev, Tihomir; Svirin, Mikhail; Jaimovich, Enrique; Fink, Rainer H. A.

    2015-01-01

    Nuclear Ca2+ is important for the regulation of several nuclear processes such as gene expression. Localized Ca2+ signals (LCSs) in skeletal muscle fibers of mice have been mainly studied as Ca2+ release events from the sarcoplasmic reticulum. Their location with regard to cell nuclei has not been investigated. Our study is based on the hypothesis that LCSs associated with nuclei are present in skeletal muscle fibers of adult mice. Therefore, we carried out experiments addressing this question and we found novel Ca2+ signals associated with nuclei of skeletal muscle fibers (with possibly attached satellite cells). We measured localized nuclear and perinuclear Ca2+ signals (NLCSs and PLCSs) alongside cytosolic localized Ca2+ signals (CLCSs) during a hypertonic treatment. We also observed NLCSs under isotonic conditions. The NLCSs and PLCSs are Ca2+ signals in the range of micrometer [FWHM (full width at half maximum): 2.75 ± 0.27 μm (NLCSs) and 2.55 ± 0.17 μm (PLCSs), S.E.M.]. Additionally, global nuclear Ca2+ signals (NGCSs) were observed. To investigate which type of Ca2+ channels contribute to the Ca2+ signals associated with nuclei in skeletal muscle fibers, we performed measurements with the RyR blocker dantrolene, the DHPR blocker nifedipine or the IP3R blocker Xestospongin C. We observed Ca2+ signals associated with nuclei in the presence of each blocker. Nifedipine and dantrolene had an inhibitory effect on the fraction of fibers with PLCSs. The situation for the fraction of fibers with NLCSs is more complex indicating that RyR is less important for the generation of NLCSs compared to the generation of PLCSs. The fraction of fibers with NLCSs and PLCSs is not reduced in the presence of Xestospongin C. The localized perinuclear and intranuclear Ca2+ signals may be a powerful tool for the cell to regulate adaptive processes as gene expression. The intranuclear Ca2+ signals may be particularly interesting in this respect. PMID:26483696

  13. Effect of spaceflight on the isotonic contractile properties of single skeletal muscle fibers in the rhesus monkey

    NASA Technical Reports Server (NTRS)

    Fitts, R. H.; Romatowski, J. G.; Blaser, C.; De La Cruz, L.; Gettelman, G. J.; Widrick, J. J.

    2000-01-01

    Experiments from both Cosmos and Space Shuttle missions have shown weightlessness to result in a rapid decline in the mass and force of rat hindlimb extensor muscles. Additionally, despite an increased maximal shortening velocity, peak power was reduced in rat soleus muscle post-flight. In humans, declines in voluntary peak isometric ankle extensor torque ranging from 15-40% have been reported following long- and short-term spaceflight and prolonged bed rest. Complete understanding of the cellular events responsible for the fiber atrophy and the decline in force, as well as the development of effective countermeasures, will require detailed knowledge of how the physiological and biochemical processes of muscle function are altered by spaceflight. The specific purpose of this investigation was to determine the extent to which the isotonic contractile properties of the slow- and fast-twitch fiber types of the soleus and gastrocnemius muscles of rhesus monkeys (Macaca mulatta) were altered by a 14-day spaceflight.

  14. Transduction of skeletal muscles with common reporter genes can promote muscle fiber degeneration and inflammation.

    PubMed

    Winbanks, Catherine E; Beyer, Claudia; Qian, Hongwei; Gregorevic, Paul

    2012-01-01

    Recombinant adeno-associated viral vectors (rAAV vectors) are promising tools for delivering transgenes to skeletal muscle, in order to study the mechanisms that control the muscle phenotype, and to ameliorate diseases that perturb muscle homeostasis. Many studies have employed rAAV vectors carrying reporter genes encoding for β-galactosidase (β-gal), human placental alkaline phosphatase (hPLAP), and green fluorescent protein (GFP) as experimental controls when studying the effects of manipulating other genes. However, it is not clear to what extent these reporter genes can influence signaling and gene expression signatures in skeletal muscle, which may confound the interpretation of results obtained in experimentally manipulated muscles. Herein, we report a strong pro-inflammatory effect of expressing reporter genes in skeletal muscle. Specifically, we show that the administration of rAAV6:hPLAP vectors to the hind limb muscles of mice is associated with dose- and time-dependent macrophage recruitment, and skeletal muscle damage. Dose-dependent expression of hPLAP also led to marked activity of established pro-inflammatory IL-6/Stat3, TNFα, IKKβ and JNK signaling in lysates obtained from homogenized muscles. These effects were independent of promoter type, as expression cassettes featuring hPLAP under the control of constitutive CMV and muscle-specific CK6 promoters both drove cellular responses when matched for vector dose. Importantly, the administration of rAAV6:GFP vectors did not induce muscle damage or inflammation except at the highest doses we examined, and administration of a transgene-null vector (rAAV6:MCS) did not cause damage or inflammation at any of the doses tested, demonstrating that GFP-expressing, or transgene-null vectors may be more suitable as experimental controls. The studies highlight the importance of considering the potential effects of reporter genes when designing experiments that examine gene manipulation in vivo.

  15. Muscle fiber characteristics of broiler breast fillets with the wooden breast condition.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Broiler breast fillets exhibiting the wooden breast condition are described as having a rigid feel and abnormal texture attributes; however, changes at the muscle fiber level in wooden breast fillets are not well understood. The objective of this study was to compare the histochemical muscle fiber ...

  16. Calcium Sparks in Intact Skeletal Muscle Fibers of the Frog

    PubMed Central

    Hollingworth, S.; Peet, J.; Chandler, W.K; Baylor, S.M.

    2001-01-01

    Calcium sparks were studied in frog intact skeletal muscle fibers using a home-built confocal scanner whose point-spread function was estimated to be ∼0.21 μm in x and y and ∼0.51 μm in z. Observations were made at 17–20°C on fibers from Rana pipiens and Rana temporaria. Fibers were studied in two external solutions: normal Ringer's ([K+] = 2.5 mM; estimated membrane potential, −80 to −90 mV) and elevated [K+] Ringer's (most frequently, [K+] = 13 mM; estimated membrane potential, −60 to −65 mV). The frequency of sparks was 0.04–0.05 sarcomere−1 s−1 in normal Ringer's; the frequency increased approximately tenfold in 13 mM [K+] Ringer's. Spark properties in each solution were similar for the two species; they were also similar when scanned in the x and the y directions. From fits of standard functional forms to the temporal and spatial profiles of the sparks, the following mean values were estimated for the morphological parameters: rise time, ∼4 ms; peak amplitude, ∼1 ΔF/F (change in fluorescence divided by resting fluorescence); decay time constant, ∼5 ms; full duration at half maximum (FDHM), ∼6 ms; late offset, ∼0.01 ΔF/F; full width at half maximum (FWHM), ∼1.0 μm; mass (calculated as amplitude × 1.206 × FWHM3), 1.3–1.9 μm3. Although the rise time is similar to that measured previously in frog cut fibers (5–6 ms; 17–23°C), cut fiber sparks have a longer duration (FDHM, 9–15 ms), a wider extent (FWHM, 1.3–2.3 μm), and a strikingly larger mass (by 3–10-fold). Possible explanations for the increase in mass in cut fibers are a reduction in the Ca2+ buffering power of myoplasm in cut fibers and an increase in the flux of Ca2+ during release. PMID:11723160

  17. Immunohistochemical myofiber typing and high-resolution myofibrillar lesion detection in LR white embedded muscle

    NASA Technical Reports Server (NTRS)

    Thompson, J. L.; Vijayan, K.; Riley, D. A.

    2000-01-01

    We have developed a method of fixing, embedding, sectioning, and staining that allows high-resolution detection of myofibrillar structure and myosin immunocytochemical muscle fiber typing in serial semithin sections of LR White plastic embedded muscle at the light microscopic level. Traditional approaches, such as cryostat sections, permit fiber typing, but small myofibrillar lesions (1-3 sarcomeres) are difficult to detect because of section thickness. Semithin sections of hydrophobic resins do not stain well either histochemically or immunocytochemically. Electron microscopy can resolve lesions and discriminate fiber types based on morphology, but the sampling area is small. Our goal was to develop a rapid method for defining both fiber type and high-resolution primary myofibrillar lesion damage. Mild fixation (1-4% paraformaldehyde, 0. 05-0.1% glutaraldehyde) and embedment in a hydrophilic resin (LR White) were used. Myofibrillar structure was extremely well preserved at the light microscopic (LM) level, and lesions could be readily resolved in Toluidine blue stained 500-nm sections. Fiber type was defined by LM immunomyosin staining of serial plastic semithin sections, which demonstrated reciprocal staining patterns for "fast (Sigma M4276) and "total" (skeletal muscle) myosins (Sigma M7523). Copyright 2000 Wiley-Liss, Inc.

  18. Impaired Organization and Function of Myofilaments in Single Muscle Fibers from a Mouse Model of Pompe Disease

    SciTech Connect

    Xu, S.; Galperin, M; Melvin, G; Horowits, R; Raben, N; Plotz, P; Yu, L

    2010-01-01

    Pompe disease, a deficiency of lysosomal acid {alpha}-glucosidase, is a disorder of glycogen metabolism that can affect infants, children, or adults. In all forms of the disease, there is progressive muscle pathology leading to premature death. The pathology is characterized by accumulation of glycogen in lysosomes, autophagic buildup, and muscle atrophy. The purpose of the present investigation was to determine if myofibrillar dysfunction in Pompe disease contributes to muscle weakness beyond that attributed to atrophy. The study was performed on isolated myofibers dissected from severely affected fast glycolytic muscle in the {alpha}-glucosidase knockout mouse model. Psoas muscle fibers were first permeabilized, so that the contractile proteins could be directly relaxed or activated by control of the composition of the bathing solution. When normalized by cross-sectional area, single fibers from knockout mice produced 6.3 N/cm{sup 2} of maximum Ca{sup 2+}-activated tension compared with 12.0 N/cm{sup 2} produced by wild-type fibers. The total protein concentration was slightly higher in the knockout mice, but concentrations of the contractile proteins myosin and actin remained unchanged. Structurally, X-ray diffraction showed that the actin and myosin filaments, normally arranged in hexagonal arrays, were disordered in the knockout muscle, and a lower fraction of myosin cross bridges was near the actin filaments in the relaxed muscle. The results are consistent with a disruption of actin and myosin interactions in the knockout muscles, demonstrating that impaired myofibrillar function contributes to weakness in the diseased muscle fibers.

  19. Control of fresh meat quality through manipulation of muscle fiber characteristics.

    PubMed

    Joo, S T; Kim, G D; Hwang, Y H; Ryu, Y C

    2013-12-01

    Variations of fresh meat quality exist because the quality traits are affected by various intrinsic and extrinsic factors. Because the meat quality is basically dependent on muscle fiber characteristics, numerous studies have reported the relationship between quality traits and fiber characteristics. Despite intensive research, the relationship is yet to be fully established, however, the present knowledge suggests several potential ways to manipulate muscle fiber characteristics to improve meat quality. The present paper reviews the definition of fresh meat quality, meat quality traits and variations of meat quality. Also, this review presents recent knowledge underlying the relationship between fresh meat quality traits and muscle fiber characteristics. Finally, the present work proposes several potential factors including breed, genotype, sex, hormone, growth performance, diet, muscle location, exercise and ambient temperature that can be used to manipulate muscle fiber characteristics and subsequently meat quality in animals.

  20. Voluntary activation level and muscle fiber recruitment of human quadriceps during lengthening contractions.

    PubMed

    Beltman, J G M; Sargeant, A J; van Mechelen, W; de Haan, A

    2004-08-01

    Voluntary activation levels during lengthening, isometric, and shortening contractions (angular velocity 60 degrees/s) were investigated by using electrical stimulation of the femoral nerve (triplet, 300 Hz) superimposed on maximal efforts. Recruitment of fiber populations was investigated by using the phosphocreatine-to-creatine ratio (PCr/Cr) of single characterized muscle fibers obtained from needle biopsies at rest and immediately after a series of 10 lengthening, isometric, and shortening contractions (1 s on/1 s off). Maximal voluntary torque was significantly higher during lengthening (270 +/- 55 N.m) compared with shortening contractions (199 +/- 47 N.m, P < 0.05) but was not different from isometric contractions (252 +/- 47 N.m). Isometric torque was higher than torque during shortening (P < 0.05). Voluntary activation level during maximal attempted lengthening contractions (79 +/- 8%) was significantly lower compared with isometric (93 +/- 5%) and shortening contractions (92 +/- 3%, P < 0.05). Mean PCr/Cr values of all fibers from all subjects at rest were 2.5 +/- 0.6, 2.0 +/- 0.7, and 2.0 +/- 0.7, respectively, for type I, IIa, and IIax fibers. After 10 contractions, the mean PCr/Cr values for grouped fiber populations (regardless of fiber type) were all significantly different from rest (1.3 +/- 0.2, 0.7 +/- 0.3, and 0.8 +/- 0.6 for lengthening, isometric, and shortening contractions, respectively; P < 0.05). The cumulative distributions of individual fiber populations after either contraction mode were significantly different from rest (P < 0.05). Curves after lengthening contractions were less shifted compared with curves from isometric and shortening contractions (P < 0.05), with a smaller shift for the type IIax compared with type I fibers in the lengthening contractions. The results indicate a reduced voluntary drive during lengthening contractions. PCr/Cr values of single fibers indicated a hierarchical order of recruitment of all fiber

  1. Aging alters contractile properties and fiber morphology in pigeon skeletal muscle.

    PubMed

    Pistilli, Emidio E; Alway, Stephen E; Hollander, John M; Wimsatt, Jeffrey H

    2014-12-01

    In this study, we tested the hypothesis that skeletal muscle from pigeons would display age-related alterations in isometric force and contractile parameters as well as a shift of the single muscle fiber cross-sectional area (CSA) distribution toward smaller fiber sizes. Maximal force output, twitch contraction durations and the force-frequency relationship were determined in tensor propatagialis pars biceps muscle from young 3-year-old pigeons, middle-aged 18-year-old pigeons, and aged 30-year-old pigeons. The fiber CSA distribution was determined by planimetry from muscle sections stained with hematoxylin and eosin. Maximal force output of twitch and tetanic contractions was greatest in muscles from young pigeons, while the time to peak force of twitch contractions was longest in muscles from aged pigeons. There were no changes in the force-frequency relationship between the age groups. Interestingly, the fiber CSA distribution in aged muscles revealed a greater number of larger sized muscle fibers, which was verified visually in histological images. Middle-aged and aged muscles also displayed a greater amount of slow myosin containing muscle fibers. These data demonstrate that muscles from middle-aged and aged pigeons are susceptible to alterations in contractile properties that are consistent with aging, including lower force production and longer contraction durations. These functional changes were supported by the appearance of slow myosin containing muscle fibers in muscles from middle-aged and aged pigeons. Therefore, the pigeon may represent an appropriate animal model for the study of aging-related alterations in skeletal muscle function and structure.

  2. Effect of cleft palate repair on the susceptibility to contraction-induced injury of single permeabilized muscle fibers from congenitally-clefted goat palates.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite cleft palate repair, velopharyngeal competence is not achieved in ~ 15% of patients, often necessitating secondary surgical correction. Velopharyngeal competence postrepair may require the conversion of levator veli palatini muscle fibers from injury-susceptible type 2 fibers to injury-resi...

  3. Unilateral lower limb suspension does not mimic bed rest or spaceflight effects on human muscle fiber function

    NASA Technical Reports Server (NTRS)

    Widrick, J. J.; Trappe, S. W.; Romatowski, J. G.; Riley, D. A.; Costill, D. L.; Fitts, R. H.

    2002-01-01

    We used Ca2+-activated skinned muscle fibers to test the hypothesis that unilateral lower leg suspension (ULLS) alters cross-bridge mechanisms of muscle contraction. Soleus and gastrocnemius biopsies were obtained from eight subjects before ULLS, immediately after 12 days of ULLS (post-0 h), and after 6 h of reambulation (post-6 h). Post-0 h soleus fibers expressing type I myosin heavy chain (MHC) showed significant reductions in diameter, absolute and specific peak Ca2+-activated force, unloaded shortening velocity, and absolute and normalized peak power. Fibers obtained from the gastrocnemius were less affected by ULLS, particularly fibers expressing fast MHC isoforms. Post-6 h soleus fibers produced less absolute and specific peak force than did post-0 h fibers, suggesting that reambulation after ULLS induced cell damage. Like bed rest and spaceflight, ULLS primarily affects soleus over gastrocnemius fibers. However, in contrast to these other models, slow soleus fibers obtained after ULLS showed a decrease in unloaded shortening velocity and a greater reduction in specific force.

  4. Green tea extract decreases muscle pathology and NF-κB immunostaining in regenerating muscle fibers of mdx mice

    PubMed Central

    Evans, Nicholas P.; Call, Jarrod A.; Bassaganya-Riera, Josep; Robertson, John L.; Grange, Robert W.

    2009-01-01

    BACKGROUND & AIMS Duchenne muscular dystrophy is a debilitating genetic disorder characterized by severe muscle wasting and early death in afflicted boys. The primary cause of this disease is mutations in the dystrophin gene resulting in massive muscle degeneration and inflammation. The purpose of this study was to determine if dystrophic muscle pathology and inflammation were decreased by pre-natal and early dietary intervention with green tea extract. METHODS Mdx breeder mice and pups were fed diets containing 0.25% or 0.5% green tea extract and compared to untreated mdx and C57BL/6J mice. Serum creatine kinase was assessed as a systemic indicator of muscle damage. Quantitative histopathological and immunohistochemical techniques were used to determine muscle pathology, macrophage infiltration, and NF-κB localization. RESULTS Early treatment of mdx mice with green tea extract significantly decreased serum creatine kinase by ~85% at age 42 days (P≤0.05). In these mice, the area of normal fiber morphology was increased by as much as ~32% (P≤0.05). The primary histopathological change was a ~21% decrease in the area of regenerating fibers (P≤0.05). NF-κB staining in regenerating muscle fibers was also significantly decreased in green tea extract-treated mdx mice when compared to untreated mdx mice. CONCLUSION Early treatment with green tea extract decreases dystrophic muscle pathology potentially by regulating NF-κB activity in regenerating muscle fibers. PMID:19897286

  5. Mitochondrial ROS regulate oxidative damage and mitophagy but not age-related muscle fiber atrophy

    PubMed Central

    Sakellariou, Giorgos K.; Pearson, Timothy; Lightfoot, Adam P.; Nye, Gareth A.; Wells, Nicola; Giakoumaki, Ifigeneia I.; Vasilaki, Aphrodite; Griffiths, Richard D.; Jackson, Malcolm J.; McArdle, Anne

    2016-01-01

    Age-related loss of skeletal muscle mass and function is a major contributor to morbidity and has a profound effect on the quality of life of older people. The potential role of age-dependent mitochondrial dysfunction and cumulative oxidative stress as the underlying cause of muscle aging remains a controversial topic. Here we show that the pharmacological attenuation of age-related mitochondrial redox changes in muscle with SS31 is associated with some improvements in oxidative damage and mitophagy in muscles of old mice. However, this treatment failed to rescue the age-related muscle fiber atrophy associated with muscle atrophy and weakness. Collectively, these data imply that the muscle mitochondrial redox environment is not a key regulator of muscle fiber atrophy during sarcopenia but may play a key role in the decline of mitochondrial organelle integrity that occurs with muscle aging. PMID:27681159

  6. Persistent Muscle Fiber Regeneration in Long Term Denervation. Past, Present, Future

    PubMed Central

    Carraro, Ugo; Boncompagni, Simona; Gobbo, Valerio; Rossini, Katia; Zampieri, Sandra; Mosole, Simone; Ravara, Barbara; Nori, Alessandra; Stramare, Roberto; Ambrosio, Francesco; Piccione, Francesco; Masiero, Stefano; Vindigni, Vincenzo; Gargiulo, Paolo; Protasi, Feliciano; Kern, Helmut; Pond, Amber

    2015-01-01

    Despite the ravages of long term denervation there is structural and ultrastructural evidence for survival of muscle fibers in mammals, with some fibers surviving at least ten months in rodents and 3-6 years in humans. Further, in rodents there is evidence that muscle fibers may regenerate even after repeated damage in the absence of the nerve, and that this potential is maintained for several months after denervation. While in animal models permanently denervated muscle sooner or later loses the ability to contract, the muscles may maintain their size and ability to function if electrically stimulated soon after denervation. Whether in mammals, humans included, this is a result of persistent de novo formation of muscle fibers is an open issue we would like to explore in this review. During the past decade, we have studied muscle biopsies from the quadriceps muscle of Spinal Cord Injury (SCI) patients suffering with Conus and Cauda Equina syndrome, a condition that fully and irreversibly disconnects skeletal muscle fibers from their damaged innervating motor neurons. We have demonstrated that human denervated muscle fibers survive years of denervation and can be rescued from severe atrophy by home-based Functional Electrical Stimulation (h-bFES). Using immunohistochemistry with both non-stimulated and the h-bFES stimulated human muscle biopsies, we have observed the persistent presence of muscle fibers which are positive to labeling by an antibody which specifically recognizes the embryonic myosin heavy chain (MHCemb). Relative to the total number of fibers present, only a small percentage of these MHCemb positive fibers are detected, suggesting that they are regenerating muscle fibers and not pre-existing myofibers re-expressing embryonic isoforms. Although embryonic isoforms of acetylcholine receptors are known to be re-expressed and to spread from the end-plate to the sarcolemma of muscle fibers in early phases of muscle denervation, we suggest that the MHCemb

  7. Muscle Fiber Size and Function in Elderly Humans: A Longitudinal Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cross-sectional studies are likely to underestimate age-related changes in skeletal muscle strength and mass. The purpose of this longitudinal study was to assess whole muscle and single muscle fiber alterations in the same cohort of 12 older (mean age: start of study=71.1+/-5.4 yrs and end of study...

  8. Function of longitudinal vs circular muscle fibers in esophageal peristalsis, deduced with mathematical modeling

    PubMed Central

    Brasseur, James G; Nicosia, Mark A; Pal, Anupam; Miller, Larry S

    2007-01-01

    We summarize from previous works the functions of circular vs. longitudinal muscle in esophageal peristaltic bolus transport using a mix of experimental data, the conservation laws of mechanics and mathematical modeling. Whereas circular muscle tone generates radial closure pressure to create a local peristaltic closure wave, longitudinal muscle tone has two functions, one physiological with mechanical implications, and one purely mechanical. Each of these functions independently reduces the tension of individual circular muscle fibers to maintain closure as a consequence of shortening of longitudinal muscle locally coordinated with increasing circular muscle tone. The physiological function is deduced by combining basic laws of mechanics with concurrent measurements of intraluminal pressure from manometry, and changes in cross sectional muscle area from endoluminal ultrasound from which local longitudinal shortening (LLS) can be accurately obtained. The purely mechanical function of LLS was discovered from mathematical modeling of peristaltic esophageal transport with the axial wall motion generated by LLS. Physiologically, LLS concentrates circular muscle fibers where closure pressure is highest. However, the mechanical function of LLS is to reduce the level of pressure required to maintain closure. The combined physiological and mechanical consequences of LLS are to reduce circular muscle fiber tension and power by as much as 1/10 what would be required for peristalsis without the longitudinal muscle layer, a tremendous benefit that may explain the existence of longitudinal muscle fiber in the gut. We also review what is understood of the role of longitudinal muscle in esophageal emptying, reflux and pathology. PMID:17457963

  9. Muscle injury induced by different types of contractions in dystrophic mdx mice.

    PubMed

    Lou, Jianwei; Bi, Wenbo; Li, Wei; Zhao, Yuying; Liu, Shuping; Zheng, Jinfan; Yan, Chuanzhu

    2012-03-01

    Studies on comparing the effect of lengthening, isometric and shortening contractions on dystrophin-deficient muscles are unavailable. We hypothesized that different types of contractions lead to different extents to which dystrophin-deficient muscles are injured. For this purpose, we developed protocols for different types of contraction-induced injury to mdx muscles in vitro. Force deficits and percentages of procion orange dye positive fibers were employed to assess the extent of injury to each muscle. Our results revealed that both the lengthening and isometric contractions resulted in significantly greater injury to extensor digitorum longus (EDL) muscles of mdx mice than to that of control (C57BL/6) mice. In contrast, the shortening contractions induced very mild and identical injury to EDL muscles of mdx and C57BL/6 mice. Then another protocol was carried out in vivo to ascertain the effect of shortening contractions on mdx muscles by achillotenotomy. Histological assessment revealed that the triceps surae muscles with excised Achilles tendon (EAT) displayed little and significantly milder injury than the normal ones did. In conclusions, the unloaded shortening contractions induce little injury to mdx muscles. The in vitro protocol for different types of contraction-induced injury is sensitive and reliable.

  10. Nebulin deficiency in adult muscle causes sarcomere defects and muscle-type-dependent changes in trophicity: novel insights in nemaline myopathy.

    PubMed

    Li, Frank; Buck, Danielle; De Winter, Josine; Kolb, Justin; Meng, Hui; Birch, Camille; Slater, Rebecca; Escobar, Yael Natelie; Smith, John E; Yang, Lin; Konhilas, John; Lawlor, Michael W; Ottenheijm, Coen; Granzier, Henk L

    2015-09-15

    Nebulin is a giant filamentous protein that is coextensive with the actin filaments of the skeletal muscle sarcomere. Nebulin mutations are the main cause of nemaline myopathy (NEM), with typical adult patients having low expression of nebulin, yet the roles of nebulin in adult muscle remain poorly understood. To establish nebulin's functional roles in adult muscle, we studied a novel conditional nebulin KO (Neb cKO) mouse model in which nebulin deletion was driven by the muscle creatine kinase (MCK) promotor. Neb cKO mice are born with high nebulin levels in their skeletal muscles, but within weeks after birth nebulin expression rapidly falls to barely detectable levels Surprisingly, a large fraction of the mice survive to adulthood with low nebulin levels (<5% of control), contain nemaline rods and undergo fiber-type switching toward oxidative types. Nebulin deficiency causes a large deficit in specific force, and mechanistic studies provide evidence that a reduced fraction of force-generating cross-bridges and shortened thin filaments contribute to the force deficit. Muscles rich in glycolytic fibers upregulate proteolysis pathways (MuRF-1, Fbxo30/MUSA1, Gadd45a) and undergo hypotrophy with smaller cross-sectional areas (CSAs), worsening their force deficit. Muscles rich in oxidative fibers do not have smaller weights and can even have hypertrophy, offsetting their specific-force deficit. These studies reveal nebulin as critically important for force development and trophicity in adult muscle. The Neb cKO phenocopies important aspects of NEM (muscle weakness, oxidative fiber-type predominance, variable trophicity effects, nemaline rods) and will be highly useful to test therapeutic approaches to ameliorate muscle weakness.

  11. Reduction in single muscle fiber rate of force development with aging is not attenuated in world class older masters athletes.

    PubMed

    Power, Geoffrey A; Minozzo, Fábio C; Spendiff, Sally; Filion, Marie-Eve; Konokhova, Yana; Purves-Smith, Maddy F; Pion, Charlotte; Aubertin-Leheudre, Mylène; Morais, José A; Herzog, Walter; Hepple, Russell T; Taivassalo, Tanja; Rassier, Dilson E

    2016-02-15

    Normal adult aging is associated with impaired muscle contractile function; however, to what extent cross-bridge kinetics are altered in aging muscle is not clear. We used a slacken restretch maneuver on single muscle fiber segments biopsied from the vastus lateralis of young adults (∼23 yr), older nonathlete (NA) adults (∼80 yr), and age-matched world class masters athletes (MA; ∼80 yr) to assess the rate of force redevelopment (ktr) and cross-bridge kinetics. A post hoc analysis was performed, and only the mechanical properties of "slow type" fibers based on unloaded shortening velocity (Vo) measurements are reported. The MA and NA were ∼54 and 43% weaker, respectively, for specific force compared with young. Similarly, when force was normalized to cross-sectional area determined via the fiber shape angularity data, both old groups did not differ, and the MA and NA were ∼43 and 48% weaker, respectively, compared with young (P < 0.05). Vo for both MA and NA old groups was 62 and 46% slower, respectively, compared with young. Both MA and NA adults had approximately two times slower values for ktr compared with young. The slower Vo in both old groups relative to young, coupled with a similarly reduced ktr, suggests impaired cross-bridge kinetics are responsible for impaired single fiber contractile properties with aging. These results challenge the widely accepted resilience of slow type fibers to cellular aging.

  12. Increased wheel-running activity in the genetically skeletal muscle fast-twitch fiber-dominant rats.

    PubMed

    Suwa, Masataka; Nakano, Hiroshi; Higaki, Yasuki; Nakamura, Tomohiro; Katsuta, Shigeru; Kumagai, Shuzo

    2003-01-01

    The purpose of the present study was to investigate whether genetic differences in muscle histochemical characteristics were related to the voluntary wheel-running activity level by using genetically fast-twitch fiber-dominant rats (FFDR) and control rats (CR). The rats were divided into four groups; sedentary CR (Sed-CR), wheel-running CR (WR-CR), sedentary FFDR (Sed-FFDR), and wheel-running FFDR (WR-FFDR). Wheel access was started at age 9 wk and lasted for 7 days. The FFDR showed a lower percentage of type I fibers of the deep portion of gastrocnemius and soleus muscles and a higher percentage of both type IIX fibers of the gastrocnemius muscle and type IIA fibers of the soleus muscle compared with CR. A higher capillary density and smaller fiber cross-sectional area were also observed in FFDR. The daily running distance in WR-FFDR was higher than in WR-CR for each 7 days. The total running distance for 7 days in WR-FFDR was 3.2-fold higher than in WR-CR. On day 7 of the 7-day test, the total number of active 1-min intervals for 24 h, the average rpm when they were active, and the maximum rpm for any single 1-min period in the WR-FFDR were significantly higher than in the WR-CR (1.5-, 2.9-, and 2.0-fold, respectively). These results suggest that mechanical or physiological muscle characteristics may thus affect the wheel-running activity level.

  13. Mild Hyperbaric Oxygen Improves Decreased Oxidative Capacity of Spinal Motoneurons Innervating the Soleus Muscle of Rats with Type 2 Diabetes.

    PubMed

    Takemura, Ai; Ishihara, Akihiko

    2016-09-01

    Rats with type 2 diabetes exhibit decreased oxidative capacity, such as reduced oxidative enzyme activity, low-intensity staining for oxidative enzymes in fibers, and no high-oxidative type IIA fibers, in the skeletal muscle, especially in the soleus muscle. In contrast, there are no data available concerning the oxidative capacity of spinal motoneurons innervating skeletal muscle of rats with type 2 diabetes. This study examined the oxidative capacity of motoneurons innervating the soleus muscle of non-obese rats with type 2 diabetes. In addition, this study examined the effects of mild hyperbaric oxygen at 1.25 atmospheres absolute with 36 % oxygen for 10 weeks on the oxidative capacity of motoneurons innervating the soleus muscle because mild hyperbaric oxygen improves the decreased oxidative capacity of the soleus muscle in non-obese rats with type 2 diabetes. Spinal motoneurons innervating the soleus muscle were identified using nuclear yellow, a retrograde fluorescent neuronal tracer. Thereafter, the cell body sizes and succinate dehydrogenase activity of identified motoneurons were analyzed. Decreased succinate dehydrogenase activity of small-sized alpha motoneurons innervating the soleus muscle was observed in rats with type 2 diabetes. The decreased succinate dehydrogenase activity of these motoneurons was improved by mild hyperbaric oxygen. Therefore, we concluded that rats with type 2 diabetes have decreased oxidative capacity in motoneurons innervating the soleus muscle and this decreased oxidative capacity is improved by mild hyperbaric oxygen.

  14. Ephrin-A3 promotes and maintains slow muscle fiber identity during postnatal development and reinnervation.

    PubMed

    Stark, Danny A; Coffey, Nathan J; Pancoast, Hannah R; Arnold, Laura L; Walker, J Peyton D; Vallée, Joanne; Robitaille, Richard; Garcia, Michael L; Cornelison, D D W

    2015-12-07

    Each adult mammalian skeletal muscle has a unique complement of fast and slow myofibers, reflecting patterns established during development and reinforced via their innervation by fast and slow motor neurons. Existing data support a model of postnatal "matching" whereby predetermined myofiber type identity promotes pruning of inappropriate motor axons, but no molecular mechanism has yet been identified. We present evidence that fiber type-specific repulsive interactions inhibit innervation of slow myofibers by fast motor axons during both postnatal maturation of the neuromuscular junction and myofiber reinnervation after injury. The repulsive guidance ligand ephrin-A3 is expressed only on slow myofibers, whereas its candidate receptor, EphA8, localizes exclusively to fast motor endplates. Adult mice lacking ephrin-A3 have dramatically fewer slow myofibers in fast and mixed muscles, and misexpression of ephrin-A3 on fast myofibers followed by denervation/reinnervation promotes their respecification to a slow phenotype. We therefore conclude that Eph/ephrin interactions guide the fiber type specificity of neuromuscular interactions during development and adult life.

  15. Effect of spaceflight on the maximal shortening velocity, morphology, and enzyme profile of fast- and slow-twitch skeletal muscle fibers in rhesus monkeys

    NASA Technical Reports Server (NTRS)

    Fitts, R. H.; Romatowski, J. G.; De La Cruz, L.; Widrick, J. J.; Desplanches, D.

    2000-01-01

    Weightlessness has been shown to cause limb muscle wasting and a reduced peak force and power in the antigravity soleus muscle. Despite a reduced peak power, Caiozzo et al. observed an increased maximal shortening velocity in the rat soleus muscle following a 14-day space flight. The major purpose of the present investigation was to determine if weightlessness induced an elevated velocity in the antigravity slow type I fibers of the rhesus monkey (Macaca mulatta), as well as to establish a cellular mechanism for the effect. Spaceflight or models of weightlessness have been shown to increase glucose uptake, elevate muscle glycogen content, and increase fatigability of the soleus muscle. The latter appears to be in part caused by a reduced ability of the slow oxidative fibers to oxidize fats. A second goal of this study was to establish the extent to which weightlessness altered the substrate profile and glycolytic and oxidative enzyme capacity of individual slow- and fast-twitch fibers.

  16. Denervation causes fiber atrophy and myosin heavy chain co-expression in senescent skeletal muscle.

    PubMed

    Rowan, Sharon L; Rygiel, Karolina; Purves-Smith, Fennigje M; Solbak, Nathan M; Turnbull, Douglas M; Hepple, Russell T

    2012-01-01

    Although denervation has long been implicated in aging muscle, the degree to which it is causes the fiber atrophy seen in aging muscle is unknown. To address this question, we quantified motoneuron soma counts in the lumbar spinal cord using choline acetyl transferase immunhistochemistry and quantified the size of denervated versus innervated muscle fibers in the gastrocnemius muscle using the in situ expression of the denervation-specific sodium channel, Nav₁.₅, in young adult (YA) and senescent (SEN) rats. To gain insights into the mechanisms driving myofiber atrophy, we also examined the myofiber expression of the two primary ubiquitin ligases necessary for muscle atrophy (MAFbx, MuRF1). MN soma number in lumbar spinal cord declined 27% between YA (638±34 MNs×mm⁻¹) and SEN (469±13 MNs×mm⁻¹). Nav₁.₅ positive fibers (1548±70 μm²) were 35% smaller than Nav₁.₅ negative fibers (2367±78 μm²; P<0.05) in SEN muscle, whereas Nav₁.₅ negative fibers in SEN were only 7% smaller than fibers in YA (2553±33 μm²; P<0.05) where no Nav₁.₅ labeling was seen, suggesting denervation is the primary cause of aging myofiber atrophy. Nav₁.₅ positive fibers had higher levels of MAFbx and MuRF1 (P<0.05), consistent with involvement of the proteasome proteolytic pathway in the atrophy of denervated muscle fibers in aging muscle. In summary, our study provides the first quantitative assessment of the contribution of denervation to myofiber atrophy in aging muscle, suggesting it explains the majority of the atrophy we observed. This striking result suggests a renewed focus should be placed on denervation in seeking understanding of the causes of and treatments for aging muscle atrophy.

  17. Denervation Causes Fiber Atrophy and Myosin Heavy Chain Co-Expression in Senescent Skeletal Muscle

    PubMed Central

    Rowan, Sharon L.; Rygiel, Karolina; Purves-Smith, Fennigje M.; Solbak, Nathan M.; Turnbull, Douglas M.; Hepple, Russell T.

    2012-01-01

    Although denervation has long been implicated in aging muscle, the degree to which it is causes the fiber atrophy seen in aging muscle is unknown. To address this question, we quantified motoneuron soma counts in the lumbar spinal cord using choline acetyl transferase immunhistochemistry and quantified the size of denervated versus innervated muscle fibers in the gastrocnemius muscle using the in situ expression of the denervation-specific sodium channel, Nav1.5, in young adult (YA) and senescent (SEN) rats. To gain insights into the mechanisms driving myofiber atrophy, we also examined the myofiber expression of the two primary ubiquitin ligases necessary for muscle atrophy (MAFbx, MuRF1). MN soma number in lumbar spinal cord declined 27% between YA (638±34 MNs×mm−1) and SEN (469±13 MNs×mm−1). Nav1.5 positive fibers (1548±70 μm2) were 35% smaller than Nav1.5 negative fibers (2367±78 μm2; P<0.05) in SEN muscle, whereas Nav1.5 negative fibers in SEN were only 7% smaller than fibers in YA (2553±33 μm2; P<0.05) where no Nav1.5 labeling was seen, suggesting denervation is the primary cause of aging myofiber atrophy. Nav1.5 positive fibers had higher levels of MAFbx and MuRF1 (P<0.05), consistent with involvement of the proteasome proteolytic pathway in the atrophy of denervated muscle fibers in aging muscle. In summary, our study provides the first quantitative assessment of the contribution of denervation to myofiber atrophy in aging muscle, suggesting it explains the majority of the atrophy we observed. This striking result suggests a renewed focus should be placed on denervation in seeking understanding of the causes of and treatments for aging muscle atrophy. PMID:22235261

  18. Efficient single muscle fiber isolation from alcohol-fixed adult muscle following β-galactosidase staining for satellite cell detection.

    PubMed

    Verma, Mayank; Asakura, Atsushi

    2011-01-01

    Staining for β-galactosidase activity for whole tissues, sections, and cells is a common method to detect expression of β-galactosidase reporter transgene as well as senescence-dependent β-galactosidase activity. Choice of fixatives is a critical step for detection of β-galactosidase activity, subsequent immunostaining, and enzymatic digestion of tissue to dissociate cells. In this report, the authors examined several aldehyde and alcohol fixatives in mouse skeletal muscle tissues for their efficiency at improving detection of β-galactosidase activity as well as detection by immunostaining. In addition, fixatives were also analyzed for their efficiency for collagenase digestion to isolate single muscle fibers on postfixed β-galactosidase-stained whole skeletal muscle tissues. The results show that fixing cells with isopropanol yields the greatest reliability and intensity in both β-galactosidase staining as well as double staining for β-galactosidase activity and antibodies. In addition, isopropanol and ethanol, but not glutaraldehyde or paraformaldehyde, allow for the isolation of single muscle fibers from the diaphragm and tibialis anterior muscles following postfixed β-galactosidase staining. Using this method, it is possible to identify the amount of cells that occupy the satellite cell compartment in single muscle fibers prepared from any muscle tissues, including tibialis anterior muscle and diaphragm.

  19. Synchronized reconstitution of muscle fibers, peripheral nerves and blood vessels by murine skeletal muscle-derived CD34(-)/45 (-) cells.

    PubMed

    Tamaki, Tetsuro; Okada, Yoshinori; Uchiyama, Yoshiyasu; Tono, Kayoko; Masuda, Maki; Wada, Mika; Hoshi, Akio; Akatsuka, Akira

    2007-10-01

    In order to establish the practical isolation and usage of skeletal muscle-derived stem cells (MDSCs), we determined reconstitution capacity of CD34(-)/CD45(-) (Sk-DN) cells as a candidate somatic stem cell source for transplantation. Sk-DN cells were enzymatically isolated from GFP transgenic mice (C57/BL6N) skeletal muscle and sorted using fluorescence activated cell sorting (FACS), and expanded by collagen gel-based cell culture with bFGF and EGF. The number of Sk-DN cells was small after sorting (2-8 x 10(4)); however, the number increased 10-20 fold (2-16 x 10(5)) after 6 days of expansion culture, and the cells maintained immature state and multipotency, expressing mRNAs for mesodermal and ectodermal cell lineages. Transplantation of expanded Sk-DN cells into the severe muscle damage model (C57/BL6N wild-type) resulted in the synchronized reconstitution of blood vessels, peripheral nerves and muscle fibers following significant recovery of total muscle mass (57%) and contractile function (55%), whereas the non-cell-transplanted control group showed around 20% recovery in both factors. These reconstitution capacities were supported by the intrinsic plasticity of Sk-DN cells that can differentiate into muscular (skeletal muscle), vascular (pericyte, endothelial cell and smooth muscle) and peripheral nerve (Schwann cells and perineurium) cell lineages that was revealed by transplantation to non-muscle tissue (beneath renal capsule) and fluorescence in situ hybridization (FISH) analysis.

  20. EUK-134 ameliorates nNOSμ translocation and skeletal muscle fiber atrophy during short-term mechanical unloading

    PubMed Central

    Kunst, Mary; Hord, Jeff M.; Lee, Yang; Joshi, Kumar; Botchlett, Rachel E.; Ramirez, Angelo; Martinez, Daniel A.

    2014-01-01

    Reduced mechanical loading during bedrest, spaceflight, and casting, causes rapid morphological changes in skeletal muscle: fiber atrophy and reduction of slow-twitch fibers. An emerging signaling event in response to unloading is the translocation of neuronal nitric oxide synthase (nNOSμ) from the sarcolemma to the cytosol. We used EUK-134, a cell-permeable mimetic of superoxide dismutase and catalase, to test the role of redox signaling in nNOSμ translocation and muscle fiber atrophy as a result of short-term (54 h) hindlimb unloading. Fischer-344 rats were divided into ambulatory control, hindlimb-unloaded (HU), and hindlimb-unloaded + EUK-134 (HU-EUK) groups. EUK-134 mitigated the unloading-induced phenotype, including muscle fiber atrophy and muscle fiber-type shift from slow to fast. nNOSμ immunolocalization at the sarcolemma of the soleus was reduced with HU, while nNOSμ protein content in the cytosol increased with unloading. Translocation of nNOS from the sarcolemma to cytosol was virtually abolished by EUK-134. EUK-134 also mitigated dephosphorylation at Thr-32 of FoxO3a during HU. Hindlimb unloading elevated oxidative stress (4-hydroxynonenal) and increased sarcolemmal localization of Nox2 subunits gp91phox (Nox2) and p47phox, effects normalized by EUK-134. Thus, our findings are consistent with the hypothesis that oxidative stress triggers nNOSμ translocation from the sarcolemma and FoxO3a dephosphorylation as an early event during mechanical unloading. Thus, redox signaling may serve as a biological switch for nNOS to initiate morphological changes in skeletal muscle fibers. PMID:24477538

  1. Sarcomere Length and Tension Changes in Tetanized Frog Muscle Fibers after Quick Stretches and Releases

    NASA Astrophysics Data System (ADS)

    Sugi, Haruo; Kobayashi, Takakazu

    1983-10-01

    The sarcomere length changes in tetanized frog muscle fibers in response to quick fiber length changes were examined along the fiber length with a high-sensitivity laser diffraction technique. The experiments were only performed with muscle fibers in which the uniform orientation and sarcomere length of the component myofibrils were well preserved during a tetanus. When the sarcomere length changes were recorded near the fixed fiber end, the delay of the onset of sarcomere length change in response to the applied fiber length change tended to be longer than that of the onset of tension changes recorded at the fixed fiber end. The magnitude of sarcomere length changes was larger near the moving fiber end than near the fixed fiber end. In the case of quick releases, the resulting sarcomere shortening tended to outlast the fiber shortening, so that the quick tension recovery started during the sarcomere shortening. These results indicate (i) that the tension changes in response to quick fiber length changes may not give direct information about the cross-bridge properties and (ii) that the viscoelastic multisegmental nature of muscle fibers should be taken into consideration in interpreting the tension responses to quick length changes.

  2. Muscle fatigue examined at different temperatures in experiments on intact mammalian (rat) muscle fibers

    PubMed Central

    Roots, H.; Ball, G.; Talbot-Ponsonby, J.; King, M.; McBeath, K.; Ranatunga, K. W.

    2009-01-01

    In experiments on small bundles of intact fibers from a rat fast muscle, in vitro, we examined the decline in force in repeated tetanic contractions; the aim was to characterize the effect of shortening and of temperature on the initial phase of muscle fatigue. Short tetanic contractions were elicited at a control repetition rate of 1/60 s, and fatigue was induced by raising the rate to 1/5 s for 2–3 min, both in isometric mode (no shortening) and in shortening mode, in which each tetanic contraction included a ramp shortening at a standard velocity. In experiments at 20°C (n = 12), the force decline during a fatigue run was 25% in the isometric mode but was significantly higher (35%) in the shortening mode. In experiments at different temperatures (10–30°C, n = 11), the tetanic frequency and duration were adjusted as appropriate, and for shortening mode, the velocity was adjusted for maximum power output. In isometric mode, fatigue of force was significantly less at 30°C (∼20%) than at 10°C (∼30%); the power output (force × velocity) was >10× higher at 30°C than at 10°C, and power decline during a fatigue run was less at 30°C (∼20–30%) than at 10°C (∼50%). The finding that the extent of fatigue is increased with shortening contractions and is lower at higher temperatures is consistent with the view that force depression by inorganic phosphate, which accumulates within fibers during activity, may be a primary cause of initial muscle fatigue. PMID:19057001

  3. Long-term, but not short-term high-fat diet induces fiber composition changes and impaired contractile force in mouse fast-twitch skeletal muscle.

    PubMed

    Eshima, Hiroaki; Tamura, Yoshifumi; Kakehi, Saori; Kurebayashi, Nagomi; Murayama, Takashi; Nakamura, Kyoko; Kakigi, Ryo; Okada, Takao; Sakurai, Takashi; Kawamori, Ryuzo; Watada, Hirotaka

    2017-04-01

    In this study, we investigated the effects of a short-term and long-term high-fat diet (HFD) on morphological and functional features of fast-twitch skeletal muscle. Male C57BL/6J mice were fed a HFD (60% fat) for 4 weeks (4-week HFD) or 12 weeks (12-week HFD). Subsequently, the fast-twitch extensor digitorum longus muscle was isolated, and the composition of muscle fiber type, expression levels of proteins involved in muscle contraction, and force production on electrical stimulation were analyzed. The 12-week HFD, but not the 4-week HFD, resulted in a decreased muscle tetanic force on 100 Hz stimulation compared with control (5.1 ± 1.4 N/g in the 12-week HFD vs. 7.5 ± 1.7 N/g in the control group; P < 0.05), whereas muscle weight and cross-sectional area were not altered after both HFD protocols. Morphological analysis indicated that the percentage of type IIx myosin heavy chain fibers, mitochondrial oxidative enzyme activity, and intramyocellular lipid levels increased in the 12-week HFD group, but not in the 4-week HFD group, compared with controls (P < 0.05). No changes in the expression levels of calcium handling-related proteins and myofibrillar proteins (myosin heavy chain and actin) were detected in the HFD models, whereas fast-troponin T-protein expression was decreased in the 12-week HFD group, but not in the 4-week HFD group (P < 0.05). These findings indicate that a long-term HFD, but not a short-term HFD, impairs contractile force in fast-twitch muscle fibers. Given that skeletal muscle strength largely depends on muscle fiber type, the impaired muscle contractile force by a HFD might result from morphological changes of fiber type composition.

  4. A multiscale chemo-electro-mechanical skeletal muscle model to analyze muscle contraction and force generation for different muscle fiber arrangements

    PubMed Central

    Heidlauf, Thomas; Röhrle, Oliver

    2014-01-01

    The presented chemo-electro-mechanical skeletal muscle model relies on a continuum-mechanical formulation describing the muscle's deformation and force generation on the macroscopic muscle level. Unlike other three-dimensional models, the description of the activation-induced behavior of the mechanical model is entirely based on chemo-electro-mechanical principles on the microscopic sarcomere level. Yet, the multiscale model reproduces key characteristics of skeletal muscles such as experimental force-length and force-velocity data on the macroscopic whole muscle level. The paper presents the methodological approaches required to obtain such a multiscale model, and demonstrates the feasibility of using such a model to analyze differences in the mechanical behavior of parallel-fibered muscles, in which the muscle fibers either span the entire length of the fascicles or terminate intrafascicularly. The presented results reveal that muscles, in which the fibers span the entire length of the fascicles, show lower peak forces, more dispersed twitches and fusion of twitches at lower stimulation frequencies. In detail, the model predicted twitch rise times of 38.2 and 17.2 ms for a 12 cm long muscle, in which the fibers span the entire length of the fascicles and with twelve fiber compartments in series, respectively. Further, the twelve-compartment model predicted peak twitch forces that were 19% higher than in the single-compartment model. The analysis of sarcomere lengths during fixed-end single twitch contractions at optimal length predicts rather small sarcomere length changes. The observed lengths range from 75 to 111% of the optimal sarcomere length, which corresponds to a region with maximum filament overlap. This result suggests that stability issues resulting from activation-induced stretches of non-activated sarcomeres are unlikely in muscles with passive forces appearing at short muscle length. PMID:25566094

  5. Muscle-specific function of the centronuclear myopathy and Charcot-Marie-Tooth neuropathy-associated dynamin 2 is required for proper lipid metabolism, mitochondria, muscle fibers, neuromuscular junctions and peripheral nerves.

    PubMed

    Tinelli, Elisa; Pereira, Jorge A; Suter, Ueli

    2013-11-01

    The ubiquitously expressed large GTPase Dynamin 2 (DNM2) plays a critical role in the regulation of intracellular membrane trafficking through its crucial function in membrane fission, particularly in endocytosis. Autosomal-dominant mutations in DNM2 cause tissue-specific human disorders. Different sets of DNM2 mutations are linked to dominant intermediate Charcot-Marie-Tooth neuropathy type B, a motor and sensory neuropathy affecting primarily peripheral nerves, or autosomal-dominant centronuclear myopathy (CNM) presenting with primary damage in skeletal muscles. To understand the underlying disease mechanisms, it is imperative to determine to which degree the primary affected cell types require DNM2. Thus, we used cell type-specific gene ablation to examine the consequences of DNM2 loss in skeletal muscle cells, the major relevant cell type involved in CNM. We found that DNM2 function in skeletal muscle is required for proper mouse development. Skeletal muscle-specific loss of DNM2 causes a reduction in muscle mass and in the numbers of muscle fibers, altered muscle fiber size distributions, irregular neuromuscular junctions (NMJs) and isolated degenerating intramuscular peripheral nerve fibers. Intriguingly, a lack of muscle-expressed DNM2 triggers an increase of lipid droplets (LDs) and mitochondrial defects. We conclude that loss of DNM2 function in skeletal muscles initiates a chain of harmful parallel and serial events, involving dysregulation of LDs and mitochondrial defects within altered muscle fibers, defective NMJs and peripheral nerve degeneration. These findings provide the essential basis for further studies on DNM2 function and malfunction in skeletal muscles in health and disease, potentially including metabolic diseases such as diabetes.

  6. Differences in muscle fiber size and associated energetic costs in phylogenetically paired tropical and temperate birds.

    PubMed

    Jimenez, Ana Gabriela; Williams, Joseph B

    2014-01-01

    Tropical and temperate birds provide a unique system to examine mechanistic consequences of life-history trade-offs at opposing ends of the pace-of-life spectrum; tropical birds tend to have a slow pace of life whereas temperate birds the opposite. Birds in the tropics have a lower whole-animal basal metabolic rate and peak metabolic rate, lower rates of reproduction, and longer survival than birds in temperate regions. Although skeletal muscle has a relatively low tissue-specific metabolism at rest, it makes up the largest fraction of body mass and therefore contributes more to basal metabolism than any other tissue. A principal property of muscle cells that influences their rate of metabolism is fiber size. The optimal fiber size hypothesis attempts to link whole-animal basal metabolic rate to the cost of maintaining muscle mass by stating that larger fibers may be metabolically cheaper to maintain since the surface area∶volume ratio (SA∶V) is reduced compared with smaller fibers and thus the amount of area to transport ions is also reduced. Because tropical birds have a reduced whole-organism metabolism, we hypothesized that they would have larger muscle fibers than temperate birds, given that larger muscle fibers have reduced energy demand from membrane Na(+)-K(+) pumps. Alternatively, smaller muscle fibers could result in a lower capacity for shivering and exercise. To test this idea, we examined muscle fiber size and Na(+)-K(+)-ATPase activity in 16 phylogenetically paired species of tropical and temperate birds. We found that 3 of the 16 paired comparisons indicated that tropical birds had significantly larger fibers, contrary to our hypothesis. Our data show that SA∶V is proportional to Na(+)-K(+)-ATPase activity in muscles of birds.

  7. Ephrin-A3 promotes and maintains slow muscle fiber identity during postnatal development and reinnervation

    PubMed Central

    Stark, Danny A.; Coffey, Nathan J.; Pancoast, Hannah R.; Arnold, Laura L.; Walker, J. Peyton D.; Vallée, Joanne; Robitaille, Richard; Garcia, Michael L.

    2015-01-01

    Each adult mammalian skeletal muscle has a unique complement of fast and slow myofibers, reflecting patterns established during development and reinforced via their innervation by fast and slow motor neurons. Existing data support a model of postnatal "matching" whereby predetermined myofiber type identity promotes pruning of inappropriate motor axons, but no molecular mechanism has yet been identified. We present evidence that fiber type–specific repulsive interactions inhibit innervation of slow myofibers by fast motor axons during both postnatal maturation of the neuromuscular junction and myofiber reinnervation after injury. The repulsive guidance ligand ephrin-A3 is expressed only on slow myofibers, whereas its candidate receptor, EphA8, localizes exclusively to fast motor endplates. Adult mice lacking ephrin-A3 have dramatically fewer slow myofibers in fast and mixed muscles, and misexpression of ephrin-A3 on fast myofibers followed by denervation/reinnervation promotes their respecification to a slow phenotype. We therefore conclude that Eph/ephrin interactions guide the fiber type specificity of neuromuscular interactions during development and adult life. PMID:26644518

  8. Spermine oxidase maintains basal skeletal muscle gene expression and fiber size and is strongly repressed by conditions that cause skeletal muscle atrophy

    PubMed Central

    Bongers, Kale S.; Fox, Daniel K.; Kunkel, Steven D.; Stebounova, Larissa V.; Murry, Daryl J.; Pufall, Miles A.; Ebert, Scott M.; Dyle, Michael C.; Bullard, Steven A.; Dierdorff, Jason M.

    2014-01-01

    Skeletal muscle atrophy is a common and debilitating condition that remains poorly understood at the molecular level. To better understand the mechanisms of muscle atrophy, we used mouse models to search for a skeletal muscle protein that helps to maintain muscle mass and is specifically lost during muscle atrophy. We discovered that diverse causes of muscle atrophy (limb immobilization, fasting, muscle denervation, and aging) strongly reduced expression of the enzyme spermine oxidase. Importantly, a reduction in spermine oxidase was sufficient to induce muscle fiber atrophy. Conversely, forced expression of spermine oxidase increased muscle fiber size in multiple models of muscle atrophy (immobilization, fasting, and denervation). Interestingly, the reduction of spermine oxidase during muscle atrophy was mediated by p21, a protein that is highly induced during muscle atrophy and actively promotes muscle atrophy. In addition, we found that spermine oxidase decreased skeletal muscle mRNAs that promote muscle atrophy (e.g., myogenin) and increased mRNAs that help to maintain muscle mass (e.g., mitofusin-2). Thus, in healthy skeletal muscle, a relatively low level of p21 permits expression of spermine oxidase, which helps to maintain basal muscle gene expression and fiber size; conversely, during conditions that cause muscle atrophy, p21 expression rises, leading to reduced spermine oxidase expression, disruption of basal muscle gene expression, and muscle fiber atrophy. Collectively, these results identify spermine oxidase as an important positive regulator of muscle gene expression and fiber size, and elucidate p21-mediated repression of spermine oxidase as a key step in the pathogenesis of skeletal muscle atrophy. PMID:25406264

  9. Spermine oxidase maintains basal skeletal muscle gene expression and fiber size and is strongly repressed by conditions that cause skeletal muscle atrophy.

    PubMed

    Bongers, Kale S; Fox, Daniel K; Kunkel, Steven D; Stebounova, Larissa V; Murry, Daryl J; Pufall, Miles A; Ebert, Scott M; Dyle, Michael C; Bullard, Steven A; Dierdorff, Jason M; Adams, Christopher M

    2015-01-15

    Skeletal muscle atrophy is a common and debilitating condition that remains poorly understood at the molecular level. To better understand the mechanisms of muscle atrophy, we used mouse models to search for a skeletal muscle protein that helps to maintain muscle mass and is specifically lost during muscle atrophy. We discovered that diverse causes of muscle atrophy (limb immobilization, fasting, muscle denervation, and aging) strongly reduced expression of the enzyme spermine oxidase. Importantly, a reduction in spermine oxidase was sufficient to induce muscle fiber atrophy. Conversely, forced expression of spermine oxidase increased muscle fiber size in multiple models of muscle atrophy (immobilization, fasting, and denervation). Interestingly, the reduction of spermine oxidase during muscle atrophy was mediated by p21, a protein that is highly induced during muscle atrophy and actively promotes muscle atrophy. In addition, we found that spermine oxidase decreased skeletal muscle mRNAs that promote muscle atrophy (e.g., myogenin) and increased mRNAs that help to maintain muscle mass (e.g., mitofusin-2). Thus, in healthy skeletal muscle, a relatively low level of p21 permits expression of spermine oxidase, which helps to maintain basal muscle gene expression and fiber size; conversely, during conditions that cause muscle atrophy, p21 expression rises, leading to reduced spermine oxidase expression, disruption of basal muscle gene expression, and muscle fiber atrophy. Collectively, these results identify spermine oxidase as an important positive regulator of muscle gene expression and fiber size, and elucidate p21-mediated repression of spermine oxidase as a key step in the pathogenesis of skeletal muscle atrophy.

  10. Degeneration of oxidative muscle fibers in HTLV-1 tax transgenic mice.

    PubMed

    Nerenberg, M I; Wiley, C A

    1989-12-01

    The HTLV-1 tax gene under control of the HTLV-1 long terminal repeat (LTR) was introduced into transgenic mice. Previously tax protein expression in the muscle and peripheral nerves of three independent mouse lines was reported. Here the localization of this transgenic protein at a cellular and subcellular level is described. Tax protein was expressed in oxidative muscle fibers that developed severe progressive atrophy. It localized to the cytoplasma where it was associated with structures resembling degenerating Z bands. This pattern of muscle fiber involvement is similar to that observed in human retroviral associated myopathy. This transgenic mouse model suggests that preferential expression of the HTLV-1 viral promoter in oxidative muscle fibers may explain the productive infection of these fibers in HTLV-1 myopathy.

  11. Effects of cannabinoids on caffeine contractures in slow and fast skeletal muscle fibers of the frog.

    PubMed

    Huerta, Miguel; Ortiz-Mesina, Mónica; Trujillo, Xóchitl; Sánchez-Pastor, Enrique; Vásquez, Clemente; Castro, Elena; Velasco, Raymundo; Montoya-Pérez, Rocío; Onetti, Carlos

    2009-05-01

    The effect of cannabinoids on caffeine contractures was investigated in slow and fast skeletal muscle fibers using isometric tension recording. In slow muscle fibers, WIN 55,212-2 (10 and 5 microM) caused a decrease in tension. These doses reduced maximum tension to 67.43 +/- 8.07% (P = 0.02, n = 5) and 79.4 +/- 14.11% (P = 0.007, n = 5) compared to control, respectively. Tension-time integral was reduced to 58.37 +/- 7.17% and 75.10 +/- 3.60% (P = 0.002, n = 5), respectively. Using the CB(1) cannabinoid receptor agonist ACPA (1 microM) reduced the maximum tension of caffeine contractures by 68.70 +/- 11.63% (P = 0.01, n = 5); tension-time integral was reduced by 66.82 +/- 6.89% (P = 0.02, n = 5) compared to controls. When the CB(1) receptor antagonist AM281 was coapplied with ACPA, it reversed the effect of ACPA on caffeine-evoked tension. In slow and fast muscle fibers incubated with the pertussis toxin, ACPA had no effect on tension evoked by caffeine. In fast muscle fibers, ACPA (1 microM) also decreased tension; the maximum tension was reduced by 56.48 +/- 3.4% (P = 0.001, n = 4), and tension-time integral was reduced by 57.81 +/- 2.6% (P = 0.006, n = 4). This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers. Moreover, we detected the presence of mRNA for the cannabinoid CB(1) receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression. In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism.

  12. Influences of temperature, oxidative stress, and phosphorylation on binding of heat shock proteins in skeletal muscle fibers.

    PubMed

    Larkins, Noni T; Murphy, Robyn M; Lamb, Graham D

    2012-09-15

    Heat shock proteins (HSPs) help maintain cellular function in stressful situations, but the processes controlling their interactions with target proteins are not well defined. This study examined the binding of HSP72, HSP25, and αB-crystallin in skeletal muscle fibers following various stresses. Rat soleus (SOL) and extensor digitorum longus (EDL) muscles were subjected in vitro to heat stress or strongly fatiguing stimulation. Superficial fibers were "skinned" by microdissection and HSP diffusibility assessed from the extent of washout following 10- to 30 min exposure to a physiological intracellular solution. In fibers from nonstressed (control) SOL muscle, >80% of each HSP is readily diffusible. However, after heating a muscle to 40°C for 30 min ∼95% of HSP25 and αB-crystallin becomes tightly bound at nonmembranous myofibrillar sites, whereas HSP72 bound at membranous sites only after heat treatment to ≥44°C. The ratio of reduced to oxidized cytoplasmic glutathione (GSH:GSSG) decreased approximately two- and fourfold after heating muscles to 40° and 45°C, respectively. The reducing agent dithiothreitol reversed HSP72 binding in heated muscles but had no effect on the other HSPs. Intense in vitro stimulation of SOL muscles, sufficient to elicit substantial oxidation-related loss of maximum force and approximately fourfold decrease in the GSH:GSSG ratio, had no effect on diffusibility of any of the HSPs. When skinned fibers from heat-treated muscles were bathed with additional exogenous HSP72, total binding increased approximately two- and 10-fold, respectively, in SOL and EDL fibers, possibly reflective of the relative sarco(endo)plasmic reticulum Ca(2+)-ATPase pump densities in the two fiber types. Phosphorylation at Ser59 on αB-crystallin and Ser85 on HSP25 increased with heat treatment but did not appear to determine HSP binding. The findings highlight major differences in the processes controlling binding of HSP72 and the two small HSPs. Binding

  13. Determining all parameters necessary to build Hill-type muscle models from experiments on single muscles.

    PubMed

    Blümel, Marcus; Hooper, Scott L; Guschlbauerc, Christoph; White, William E; Büschges, Ansgar

    2012-11-01

    Characterizing muscle requires measuring such properties as force-length, force-activation, and force-velocity curves. These characterizations require large numbers of data points because both what type of function (e.g., linear, exponential, hyperbolic) best represents each property, and the values of the parameters in the relevant equations, need to be determined. Only a few properties are therefore generally measured in experiments on any one muscle, and complete characterizations are obtained by averaging data across a large number of muscles. Such averaging approaches can work well for muscles that are similar across individuals. However, considerable evidence indicates that large inter-individual variation exists, at least for some muscles. This variation poses difficulties for across-animal averaging approaches. Methods to fully describe all muscle's characteristics in experiments on individual muscles would therefore be useful. Prior work in stick insect extensor muscle has identified what functions describe each of this muscle's properties and shown that these equations apply across animals. Characterizing these muscles on an individual-by-individual basis therefore requires determining only the values of the parameters in these equations, not equation form. We present here techniques that allow determining all these parameter values in experiments on single muscles. This technique will allow us to compare parameter variation across individuals and to model muscles individually. Similar experiments can likely be performed on single muscles in other systems. This approach may thus provide a widely applicable method for characterizing and modeling muscles from single experiments.

  14. Dystrophic skeletal muscle fibers display alterations at the level of calcium microdomains

    PubMed Central

    DiFranco, Marino; Woods, Christopher E.; Capote, Joana; Vergara, Julio L.

    2008-01-01

    The spatiotemporal properties of the Ca2+-release process in skeletal muscle fibers from normal and mdx fibers were determined using the confocal-spot detection technique. The Ca2+ indicator OGB-5N was used to record action potential-evoked fluorescence signals at consecutive locations separated by 200 nm along multiple sarcomeres of FDB fibers loaded with 10- and 30-mM EGTA. Three-dimensional reconstructions of fluorescence transients demonstrated the existence of microdomains of increased fluorescence around the Ca2+-release sites in both mouse strains. The Ca2+ microdomains in mdx fibers were regularly spaced along the fiber axis, displaying a distribution similar to that seen in normal fibers. Nevertheless, both preparations differed in that in 10-mM EGTA Ca2+ microdomains had smaller amplitudes and were wider in mdx fibers than in controls. In addition, Ca2+-dependent fluorescence transients recorded at selected locations within the sarcomere of mdx muscle fibers were not only smaller, but also slower than their counterparts in normal fibers. Notably, differences in the spatial features of the Ca2+ microdomains recorded in mdx and normal fibers, but not in the amplitude and kinetics of the Ca2+ transients, were eliminated in 30-mM EGTA. Our results consistently demonstrate that Ca2+-release flux calculated from release sites in mdx fibers is uniformly impaired with respect to those normal fibers. The Ca2+-release reduction is consistent with that previously measured using global detection techniques. PMID:18787128

  15. Embryonic arsenic exposure reduces the number of muscle fibers in killifish (Fundulus heteroclitus).

    PubMed

    D'Amico, Angela R; Gibson, Alec W; Bain, Lisa J

    2014-01-01

    Arsenic is a contaminant of drinking water and has been correlated with adverse developmental outcomes such as low birth weight, reduced weight gain, and altered locomotor activity. Previous research has shown that killifish (Fundulus heteroclitus) exposed to high arsenic levels during embryogenesis had smaller muscle fiber diameters. The current study was designed to determine whether changes in muscle fibers persisted, were exacerbated, or resolved over time. Killifish embryos were exposed to 0-5 ppm arsenite and, upon hatching, were transferred into either clean water or continued receiving the same exposure to arsenic for up to 16 weeks. Arsenic significantly decreased the weight of both embryonic-only exposed juveniles and continuously exposed juveniles between 4 and 16 weeks of development at concentrations as low as 0.8 ppm. Although arsenite exposure increased the percentage of small diameter fibers during the early weeks, fiber diameters returned to control levels in the embryonic-only exposed fish. However, muscle fiber density was still reduced to 85.7%, 80.3%, and 73.8% of control for the 0.8, 2, and 5 ppm embryonic-only exposure groups, respectively, even after 16 weeks of development. These results indicate that while continuous exposure to arsenic may alter the size of muscle fibers, embryonic-only exposure to arsenic has lasting effects on the number of muscle fibers formed.

  16. Imaging mass spectrometry reveals fiber-specific distribution of acetylcarnitine and contraction-induced carnitine dynamics in rat skeletal muscles.

    PubMed

    Furuichi, Yasuro; Goto-Inoue, Naoko; Manabe, Yasuko; Setou, Mitsutoshi; Masuda, Kazumi; Fujii, Nobuharu L

    2014-10-01

    Carnitine is well recognized as a key regulator of long-chain fatty acyl group translocation into the mitochondria. In addition, carnitine, as acetylcarnitine, acts as an acceptor of excess acetyl-CoA, a potent inhibitor of pyruvate dehydrogenase. Here, we provide a new methodology for accurate quantification of acetylcarnitine content and determination of its localization in skeletal muscles. We used matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) to visualize acetylcarnitine distribution in rat skeletal muscles. MALDI-IMS and immunohistochemistry of serial cross-sections showed that acetylcarnitine was enriched in the slow-type muscle fibers. The concentration of ATP was lower in muscle regions with abundant acetylcarnitine, suggesting a relationship between acetylcarnitine and metabolic activity. Using our novel method, we detected an increase in acetylcarnitine content after muscle contraction. Importantly, this increase was not detected using traditional biochemical assays of homogenized muscles. We also demonstrated that acetylation of carnitine during muscle contraction was concomitant with glycogen depletion. Our methodology would be useful for the quantification of acetylcarnitine and its contraction-induced kinetics in skeletal muscles.

  17. Genetics Home Reference: congenital fiber-type disproportion

    MedlinePlus

    ... health and development? More about Mutations and Health Inheritance Pattern Congenital fiber-type disproportion can have multiple inheritance patterns. When this condition is caused by mutations in ...

  18. Protein turnover and cellular stress in mildly and severely affected muscles from patients with limb girdle muscular dystrophy type 2I.

    PubMed

    Hauerslev, Simon; Sveen, Marie L; Vissing, John; Krag, Thomas O

    2013-01-01

    Patients with Limb girdle muscular dystrophy type 2I (LGMD2I) are characterized by progressive muscle weakness and wasting primarily in the proximal muscles, while distal muscles often are spared. Our aim was to investigate if wasting could be caused by impaired regeneration in the proximal compared to distal muscles. Biopsies were simultaneously obtained from proximal and distal muscles of the same patients with LGMD2I (n = 4) and healthy subjects (n = 4). The level of past muscle regeneration was evaluated by counting internally nucleated fibers and determining actively regenerating fibers by using the developmental markers embryonic myosin heavy chain (eMHC) and neural cell adhesion molecule (NCAM) and also assessing satellite cell activation status by myogenin positivity. Severe muscle histopathology was occasionally observed in the proximal muscles of patients with LGMD2I whereas distal muscles were always relatively spared. No difference was found in the regeneration markers internally nucleated fibers, actively regenerating fibers or activation status of satellite cells between proximal and distal muscles. Protein turnover, both synthesis and breakdown, as well as cellular stress were highly increased in severely affected muscles compared to mildly affected muscles. Our results indicate that alterations in the protein turnover and myostatin levels could progressively impair the muscle mass maintenance and/or regeneration resulting in gradual muscular atrophy.

  19. Laser ablation of Drosophila embryonic motoneurons causes ectopic innervation of target muscle fibers

    NASA Technical Reports Server (NTRS)

    Chang, T. N.; Keshishian, H.

    1996-01-01

    We have tested the effects of neuromuscular denervation in Drosophila by laser-ablating the RP motoneurons in intact embryos before synaptogenesis. We examined the consequences of this ablation on local synaptic connectivity in both 1st and 3rd instar larvae. We find that the partial or complete loss of native innervation correlates with the appearance of alternate inputs from neighboring motor endings and axons. These collateral inputs are found at ectopic sites on the denervated target muscle fibers. The foreign motor endings are electrophysiologically functional and are observed on the denervated muscle fibers by the 1st instar larval stage. Our data are consistent with the existence of a local signal from the target environment, which is regulated by innervation and influences synaptic connectivity. Our results show that, despite the stereotypy of Drosophila neuromuscular connections, denervation can induce local changes in connectivity in wild-type Drosophila, suggesting that mechanisms of synaptic plasticity may also be involved in normal Drosophila neuromuscular development.

  20. Quantitative diffusion tensor MRI-based fiber tracking of human skeletal muscle.

    PubMed

    Lansdown, Drew A; Ding, Zhaohua; Wadington, Megan; Hornberger, Jennifer L; Damon, Bruce M

    2007-08-01

    Diffusion-tensor magnetic resonance imaging (DT-MRI) offers great potential for understanding structure-function relationships in human skeletal muscles. The purposes of this study were to demonstrate the feasibility of using in vivo human DT-MRI fiber tracking data for making pennation angle measurements and to test the hypothesis that heterogeneity in the orientation of the tibialis anterior (TA) muscle's aponeurosis would lead to heterogeneity in pennation angle. Eight healthy subjects (5 male) were studied. T(1)-weighted anatomical MRI and DT-MRI data were acquired of the TA muscle. Fibers were tracked from the TA's aponeurosis by following the principal eigenvector. The orientations of the aponeurosis and muscle fiber tracts in the laboratory frame of reference and the orientation of the fiber tracts with respect to the aponeurosis [i.e., the pennation angle (theta)] were determined. The muscle fiber orientations, when expressed relative to the laboratory frame of reference, did not change as functions of superior-to-inferior position. The sagittal and coronal orientations of the aponeurosis did not change in practically significant manners either, but the aponeurosis' axial orientation changed by approximately 40 degrees . As a result, the mean value for theta decreased from 16.3 (SD 6.9) to 11.4 degrees (SD 5.0) along the muscle's superior-to-inferior direction. The mean value of theta was greater in the deep than in the superficial compartment. We conclude that pennation angle measurements of human muscle made using DT-MRI muscle fiber tracking are feasible and reveal that in the foot-head direction, there is heterogeneity in the pennation properties of the human TA muscle.

  1. A mathematical model of force transmission from intrafascicularly terminating muscle fibers.

    PubMed

    Sharafi, Bahar; Blemker, Silvia S

    2011-07-28

    Many long skeletal muscles are comprised of fibers that terminate intrafascicularly. Force from terminating fibers can be transmitted through shear within the endomysium that surrounds fibers or through tension within the endomysium that extends from fibers to the tendon; however, it is unclear which pathway dominates in force transmission from terminating fibers. The purpose of this work was to develop mathematical models to (i) compare the efficacy of lateral (through shear) and longitudinal (through tension) force transmission in intrafascicularly terminating fibers, and (ii) determine how force transmission is affected by variations in the structure and properties of fibers and the endomysium. The models demonstrated that even though the amount of force that can be transmitted from an intrafascicularly terminating fiber is dependent on fiber resting length (the unstretched length at which passive stress is zero), endomysium shear modulus, and fiber volume fraction (the fraction of the muscle cross-sectional area that is occupied by fibers), fibers that have values of resting length, shear modulus, and volume fraction within physiologic ranges can transmit nearly all of their peak isometric force laterally through shearing of the endomysium. By contrast, the models predicted only limited force transmission ability through tension within the endomysium that extends from the fiber to the tendon. Moreover, when fiber volume fraction decreases to unhealthy ranges (less than 50%), the force-transmitting potential of terminating fibers through shearing of the endomysium decreases significantly. The models presented here support the hypothesis that lateral force transmission through shearing of the endomysium is an effective mode of force transmission in terminating fibers.

  2. Transcriptional regulation of acetylcholinesterase-associated collagen ColQ in fast- and slow-twitch muscle fibers.

    PubMed

    Ting, Annie K L; Siow, Nina L; Kong, L W; Tsim, Karl W K

    2005-12-15

    The presence of a collagenous protein (ColQ) characterizes the collagen-tailed forms of acetylcholinesterase (AChE) and butyrylcholinesterase at vertebrate neuromuscular junctions, which is tethered in the synaptic basal lamina. ColQ subunits, differing mostly by their signal sequences, are encoded by transcripts ColQ-1 and ColQ-1a, which are differentially expressed in slow- and fast-twitch muscles in mammals, respectively. Both ColQ transcripts are derived from a single COLQ gene. Transcripts encoding ColQ increased during myogenic differentiation of C2C12 cells; the increase was in parallel with AChE catalytic subunit. Quantitative PCR analysis indicated that the increase during the myotube formation was due to the up regulation of ColQ-1 transcript instead of ColQ-1a. In order to reveal the regulatory mechanism of ColQ transcripts, two distinct promoters, pColQ-1 and pColQ-1a, were isolated from human COLQ gene. The ColQ promoters showed a muscle fiber type-specific expression pattern, and which was in line with the expression of endogenous transcript. After in vivo DNA transfection, pColQ-1 showed strong activity in slow-twitch muscle (e.g. soleus), while pColQ-1a was preferably expressed in fast-twitch muscle (e.g. tibialis). Mutation analysis of the ColQ promoters suggested that the muscle fiber type-specific expression pattern of ColQ transcripts was regulated by a slow upsteam regulatory element (SURE) and a fast intronic regulatory element (FIRE). These results explain the specific expression patterns of collagen-tailed AChE in slow and fast muscle fibers.

  3. Muscle fibers in the central nervous system of nemerteans: spatial organization and functional role.

    PubMed

    Petrov, A A; Zaitseva, O V

    2012-08-01

    The system of muscle fibers associated with the brain and lateral nerve cords is present in all major groups of enoplan nemerteans. Unfortunately, very little is known about the functional role and spatial arrangement of these muscles of the central nervous system. This article examines the architecture of the musculature of the central nervous system in two species of monostiliferous nemerteans (Emplectonema gracile and Tetrastemma cf. candidum) using phalloidin staining and confocal microscopy. The article also briefly discusses the body-wall musculature and the muscles of the cephalic region. In both species, the lateral nerve cords possess two pairs of cardinal muscles that run the length of the nerve cords and pass through the ventral cerebral ganglia. A system of peripheral muscles forms a meshwork around the lateral nerve cords in E. gracile. The actin-rich processes that ramify within the nerve cords in E. gracile (transverse fibers) might represent a separate population of glia-like cells or sarcoplasmic projections of the peripheral muscles of the central nervous system. The lateral nerve cords in T. cf. candidum lack peripheral muscles but have muscles similar in their position and orientation to the transverse fibers. The musculature of the central nervous system is hypothesized to function as a support system for the lateral nerve cords and brain, preventing rupturing and herniation of the nervous tissue during locomotion. The occurrence of muscles of the central nervous system in nemerteans and other groups and their possible relevance in taxonomy are discussed.

  4. Pubovisceralis Muscle Fiber Architecture Determination: Comparison Between Biomechanical Modeling and Diffusion Tensor Imaging.

    PubMed

    Brandão, Sofia; Parente, Marco; Silva, Elisabete; Da Roza, Thuane; Mascarenhas, Teresa; Leitão, João; Cunha, João; Natal Jorge, Renato; Nunes, Rita Gouveia

    2017-01-17

    Biomechanical analysis of pelvic floor dysfunction requires knowledge of certain biomechanical parameters, such as muscle fiber direction, in order to adequately model function. Magnetic resonance (MR) diffusion tensor imaging (DTI) provides an estimate of overall muscle fiber directionality based on the mathematical description of water diffusivity. This work aimed at evaluating the concurrence between pubovisceralis muscle fiber representations obtained from DTI, and the maximum principal stress lines obtained through the finite element method. Seven datasets from axial T2-weighted images were used to build numerical models, and muscle fiber orientation estimated from the DT images. The in-plane projections of the first eigenvector of both vector fields describing muscle fiber orientation were extracted and compared. The directional consistency was evaluated by calculating the angle between the normalized vectors for the entire muscle and also for the right and left insertions, middle portions, and anorectal area. The values varied between 28° ± 6 (right middle portion) and 34° ± 9 (anorectal area), and were higher than the angular precision of the DT estimates, evaluated using wild bootstrapping analysis. Angular dispersion ranged from 17° ± 4 (left middle portion) to 23° ± 5 (anorectal area). Further studies are needed to examine acceptability of these differences when integrating the vectors estimated from DTI in the numerical analysis.

  5. Spontaneous tension oscillation (SPOC) of muscle fibers and myofibrils minimum requirements for SPOC.

    PubMed

    Ishiwata, S; Anazawa, T; Fujita, T; Fukuda, N; Shimizu, H; Yasuda, K

    1993-01-01

    Several years ago, we found a new chemical condition for the spontaneous oscillatory contraction of glycerinated skeletal muscle and named it "SPOC". The condition was such that MgATP coexists with its hydrolytic products, MgADP and inorganic phosphate (Pi). Micromolar concentrations of free Ca2+ were not necessarily required for this oscillation. Here, we summarize our recent work on the mechano-chemical properties of SPOC not only in glycerinated single fibers and myofibrils of skeletal muscle (fast type) but also in glycerinated small bundles of cardiac muscle; the isometric tension and its oscillation were examined at various concentrations of MgATP, MgADP and Pi while controlling the concentration of free Ca2+; we constructed a three-dimensional "state diagram" taken against the concentrations of MgADP, Pi and free Ca2+. The 3-D state diagram clearly showed the existence of three regions corresponding to three muscular states; the SPOC region was located in between the regions for contraction (without oscillation) and relaxation. Based on these results, we discuss the mechanism of SPOC, especially the minimum requirements for its occurrence. Finally, we suggest that slow shortening and quick lengthening repeatedly occur every half-sarcomere through the transition between the two states, where weak-force-generating complexes or strong-force-generating complexes are dominant; the transition may be induced by a coupling with the mechanical states of cross-bridges and/or thin filaments.

  6. Spaceflight and growth effects on muscle fibers in the rhesus monkey

    NASA Technical Reports Server (NTRS)

    Bodine-Fowler, Sue C.; Roy, Roland R.; Rudolph, William; Haque, Naz; Kozlovskaia, Inessa B.; Edgerton, V. R.

    1992-01-01

    The effect of a 14-day spaceflight onboard Cosmos 2044 on selected morphological and metabolic properties of single muscle fibers was investigated in a nonhuman primate, Macaca mulatta. It is concluded that the 14-day spaceflight had little impact on fiber size in the soleus (S) and medial gastrocnemius (MG) muscles, whereas it appeared to be a slight decrease in sized in the tibialis anterior (TA). The mean fiber size in the postflight biopsies increased relative to preflight values. The mean fiber succinate dehydrogenase activity was found to decrease in the MG, whereas there was no apparent effect of spaceflight on the s and ta muscles. The differences in response of the S, MG, and TA to spaceflight in monkeys vs rats may be related to a species responsiveness to spaceflight, the manner in which the animals were restrained, and/or the possibility that the ankle musculature was able to function against a load while in space.

  7. The role of nitric oxide in muscle fibers with oxidative phosphorylation defects

    SciTech Connect

    Tengan, Celia H. . E-mail: chtengan@neuro.epm.br; Kiyomoto, Beatriz H.; Godinho, Rosely O.; Gamba, Juliana; Neves, Afonso C.; Schmidt, Beny; Oliveira, Acary S.B.; Gabbai, Alberto A.

    2007-08-03

    NO has been pointed as an important player in the control of mitochondrial respiration, especially because of its inhibitory effect on cytochrome c oxidase (COX). However, all the events involved in this control are still not completely elucidated. We demonstrate compartmentalized abnormalities on nitric oxide synthase (NOS) activity on muscle biopsies of patients with mitochondrial diseases. NOS activity was reduced in the sarcoplasmic compartment in COX deficient fibers, whereas increased activity was found in the sarcolemma of fibers with mitochondrial proliferation. We observed increased expression of neuronal NOS (nNOS) in patients and a correlation between nNOS expression and mitochondrial content. Treatment of skeletal muscle culture with an NO donor induced an increase in mitochondrial content. Our results indicate specific roles of NO in compensatory mechanisms of muscle fibers with mitochondrial deficiency and suggest the participation of nNOS in the signaling process of mitochondrial proliferation in human skeletal muscle.

  8. Measurement of the Impedance of Frog Skeletal Muscle Fibers

    PubMed Central

    Valdiosera, R.; Clausen, C.; Eisenberg, R. S.

    1974-01-01

    Impedance measurements are necessary to determine the passive electrical properties of cells including the equivalent circuits of the several pathways for current flow. Such measurements are usually made with microelectrodes of high impedance (some 15 MΩ) over a wide frequency range (1-10,000 Hz) and so are subject to many errors. An input amplifier has been developed which has negligible phase shift in this frequency range because it uses negative feedback to keep tiny the voltage on top of the microelectrode. An important source of artifact is the extracellular potential produced by capacitive current flow through the wall of the microelectrodes and the effective resistance of the bathing solution. This artifact is reduced some 10 times by shielding the current microelectrode with a conductive paint. The residual artifact is analyzed, measured, and subtracted from our results. The interelectrode coupling capacitance is reduced below 2 × 10-17 F and can be neglected. Phase and amplitude measurements are made with phase-sensitive detectors insensitive to noise. The entire apparatus is calibrated at different signal to noise ratios and the nature of the extracellular potential is investigated. The phase shift in the last 5-20 μm of the microelectrode tip is shown to be small and quite independent of frequency under several conditions. Experimental measurements of the phase characteristic of muscle fibers in normal Ringer are presented. The improvements in apparatus and the physiological significance of impedance measurements are discussed. It is suggested that the interpretation of impedance measurements is sensitive to small errors and so it is necessary to present objective evidence of the reliability of one's apparatus and measurements. PMID:4857358

  9. Muscle activation of paraspinal muscles in different types of high heels during standing

    PubMed Central

    Han, Dongwook

    2015-01-01

    [Purpose] This study researched the effects of different types of high heels on the muscles surrounding the cervical spine, the thoracic spine, and the lumbar spine by analyzing muscle activation of the paraspinal muscles during standing while wearing high heels. The high heels were all of the same height: 8 cm. [Subjects and Methods] The 28 subjects in this experiment were females in their 20s with a foot size of 225–230 mm and a normal gait pattern. To measure the muscle activation of the paraspinal muscles, EMG electrodes were attached on the paraspinal muscles around C6, T7, and L5. The muscle activation during standing while wearing 8-cm-high wedge heels, setback heels, and French heels was then measured. The measurements were performed 3 times each, and the mean value was used for analysis. [Results] The levels of muscle activation of the paraspinal muscles induced by standing on wedge heels, setback heels, and French heels in the cervical and lumbar areas were significantly higher than those induced by standing on bare feet. But there was no significant difference according to the heel types. [Conclusion] The height of the heels presented a greater variable than the width of the heels on the muscle activation of paraspinal muscles. Therefore, wearing high heels is not recommended for those who have pain or functional problems in the cervical and/or lumbar spine. PMID:25642040

  10. Muscle activation of paraspinal muscles in different types of high heels during standing.

    PubMed

    Han, Dongwook

    2015-01-01

    [Purpose] This study researched the effects of different types of high heels on the muscles surrounding the cervical spine, the thoracic spine, and the lumbar spine by analyzing muscle activation of the paraspinal muscles during standing while wearing high heels. The high heels were all of the same height: 8 cm. [Subjects and Methods] The 28 subjects in this experiment were females in their 20s with a foot size of 225-230 mm and a normal gait pattern. To measure the muscle activation of the paraspinal muscles, EMG electrodes were attached on the paraspinal muscles around C6, T7, and L5. The muscle activation during standing while wearing 8-cm-high wedge heels, setback heels, and French heels was then measured. The measurements were performed 3 times each, and the mean value was used for analysis. [Results] The levels of muscle activation of the paraspinal muscles induced by standing on wedge heels, setback heels, and French heels in the cervical and lumbar areas were significantly higher than those induced by standing on bare feet. But there was no significant difference according to the heel types. [Conclusion] The height of the heels presented a greater variable than the width of the heels on the muscle activation of paraspinal muscles. Therefore, wearing high heels is not recommended for those who have pain or functional problems in the cervical and/or lumbar spine.

  11. Novel demonstration of amyloid-β oligomers in sporadic inclusion-body myositis muscle fibers.

    PubMed

    Nogalska, Anna; D'Agostino, Carla; Engel, W King; Klein, William L; Askanas, Valerie

    2010-11-01

    Accumulation of amyloid-β (Aβ) within muscle fibers has been considered an upstream step in the development of the s-IBM pathologic phenotype. Aβ42, which is considered more cytotoxic than Aβ40 and has a higher propensity to oligomerize, is preferentially increased in s-IBM muscle fibers. In Alzheimer disease (AD), low-molecular weight Aβ oligomers and toxic oligomers, also referred to as "Aβ-Derived Diffusible Ligands" (ADDLs), are considered strongly cytotoxic and proposed to play an important pathogenic role. ADDLs have been shown to be increased in AD brain. We now report for the first time that in s-IBM muscle biopsies Aβ-dimer, -trimer, and -tetramer are identifiable by immunoblots. While all the s-IBM samples we studied had Aβ-oligomers, their molecular weights and intensity varied between the patient samples. None of the control muscle biopsies had Aβ oligomers. Dot-immunoblots using highly specific anti-ADDL monoclonal antibodies also showed highly increased ADDLs in all s-IBM biopsies studied, while controls were negative. By immunofluorescence, in some of the abnormal s-IBM muscle fibers ADDLs were accumulated in the form of plaque-like inclusions, and were often increased diffusely in very small fibers. Normal and disease-controls were negative. By gold-immuno-electron microscopy, ADDL-immunoreactivities were in close proximity to 6-10 nm amyloid-like fibrils, and also were immunodecorating amorphous and floccular material. In cultured human muscle fibers, we found that inhibition of autophagy led to the accumulation of Aβ oligomers. This novel demonstration of Aβ42 oligomers in s-IBM muscle biopsy provides additional evidence that intra-muscle fiber accumulation of Aβ42 oligomers in s-IBM may contribute importantly to s-IBM pathogenic cascade.

  12. Myosin types in cultured muscle cells

    PubMed Central

    1980-01-01

    Fluorescent antibodies against fast skeletal, slow skeletal, and ventricular myosins were applied to muscle cultures from embryonic pectoralis and ventricular myocadium of the chicken. A number of spindle-shaped mononucleated cells, presumably myoblasts, and all myotubes present in skeletal muscle cultures were labeled by all three antimyosin antisera. In contrast, in cultures from ventricular myocardium all muscle cells were labeled by anti-ventricular myosin, whereas only part of them were stained by anti-slow skeletal myosin and rare cells reacted with anti-fast skeletal myosin. The findings indicate that myosin(s) present in cultured embryonic skeletal muscle cells contains antigenic determinants similar to those present in adult fast skeletal, slow skeletal, and ventricular myosins. PMID:6156177

  13. Adaptation of fibers in fast-twitch muscles of rats to spaceflight and hindlimb suspension

    NASA Technical Reports Server (NTRS)

    Jiang, Bian; Ohira, Yoshi; Roy, Roland R.; Nguyen, Quyet; Il'ina-Kakueva, E. I.; Oganov, V.; Edgerton, V. R.

    1992-01-01

    The adaptation of single fibers in medial gastrocnemius (MG), a fast-twitch extensor, and in tibialis anterior (TA), a fast-twitch flexor, was studied after 14 days of spaceflight onboard Cosmos 2044 or hindlimb suspension. Quantitative myosin ATPase activities of single fibers were measured in flight and suspended rats. Each of the enzyme and size measurements were directly correlated within each fiber with respect to its qualitative myosin ATPase staining properties and its expression of fast, slow, or both myosin heavy chains (MHC). The percentage of slow- and fast-twitch fibers of the MG and TA were found to be unchanged. Mean fiber size of all fibers was unaffected after flight or suspension. The ATPase activity in the MG was higher in flight than in control or suspended rats. In comparison to Cosmos 1887 spaceflight, the adaptations in the muscle fibers of the MG were more moderate.

  14. Clustering of the human skeletal muscle fibers using linear programming and angular Hilbertian metrics.

    PubMed

    Neji, Radhouène; Besbes, Ahmed; Komodakis, Nikos; Deux, Jean-François; Maatouk, Mezri; Rahmouni, Alain; Bassez, Guillaume; Fleury, Gilles; Paragios, Nikos

    2009-01-01

    In this paper, we present a manifold clustering method fo the classification of fibers obtained from diffusion tensor images (DTI) of the human skeletal muscle. Using a linear programming formulation of prototype-based clustering, we propose a novel fiber classification algorithm over manifolds that circumvents the necessity to embed the data in low dimensional spaces and determines automatically the number of clusters. Furthermore, we propose the use of angular Hilbertian metrics between multivariate normal distributions to define a family of distances between tensors that we generalize to fibers. These metrics are used to approximate the geodesic distances over the fiber manifold. We also discuss the case where only geodesic distances to a reduced set of landmark fibers are available. The experimental validation of the method is done using a manually annotated significant dataset of DTI of the calf muscle for healthy and diseased subjects.

  15. Muscle fibre types in the external eye muscles of the pigeon, Columba livia.

    PubMed

    McVean, A; Stelling, J; Rowlerson, A

    1987-10-01

    Fibre typing with antisera raised against specific myosin types from muscles of known physiological properties were used to characterise the fibre types within the oculorotatory muscles of pigeons. Fibres reacting strongly to antiserum anti-ALD (specific for tonic fibre myosin) were found lying along the global margin of the muscle and also in a layer lying immediately beneath a discrete band of fibres running along the orbital margin. These fibres resembled those of the skeletal muscle ALD in their type properties. Using another antiserum, anti-I, specific for slow twitch and to a lesser extent, slow tonic myosins, it was possible to identify another slow fibre type which formed the orbital layer and also lay scattered randomly through the body of the muscle. No equivalent to this type was found in the skeletal muscles ALD or iliofibularis. The remaining fibres which did not react with either anti-ALD or anti-I formed 58% of the fibre population and reacted with an antiserum specific for fast myosin. However, their response to alkali preincubation suggests that the fast fibres of eye muscles also contain a myosin which is different from those in skeletal muscle.

  16. Sphingomyelinase depresses force and calcium sensitivity of the contractile apparatus in mouse diaphragm muscle fibers

    PubMed Central

    Ferreira, Leonardo F.; Moylan, Jennifer S.; Stasko, Shawn; Smith, Jeffrey D.; Campbell, Kenneth S.

    2012-01-01

    Diseases that result in muscle weakness, e.g., heart failure, are characterized by elevated sphingomyelinase (SMase) activity. In intact muscle, SMase increases oxidants that contribute to diminished muscle force. However, the source of oxidants, specific processes of muscle contraction that are dysfunctional, and biochemical changes underlying the weakness elicited by SMase remain unknown. We tested three hypotheses: 1) SMase-induced depression of muscle force is mediated by mitochondrial reactive oxygen species (ROS), 2) SMase depresses force and calcium sensitivity of the contractile apparatus, and 3) SMase promotes oxidation and phosphorylation of myofibrillar proteins. Our experiments included intact muscle bundles, permeabilized single fibers, and isolated myofibrillar proteins. The mitochondrial-targeted antioxidant d-Arg-2′,6′-dimethyl-Tyr-Lys-Phe-NH2, decreased cytosolic oxidants and protected intact muscle bundles from weakness stimulated by SMase. SMase depressed maximal calcium-activated force by 20% in permeabilized single fibers (in kN/m2: control 117 ± 6; SMase 93 ± 8; P < 0.05). Calcium sensitivity of permeabilized single fibers decreased from 5.98 ± 0.03 (control) to 5.91 ± 0.02 (SMase; P < 0.05). Myofibrillar protein nitrotyrosines, carbonyls, and phosphorylation were unaltered by SMase. Our study shows that the fall in specific force of intact muscle elicited by SMase is mediated by mitochondrial ROS and can be attributed largely to dysfunction of the contractile apparatus. PMID:22362402

  17. Matrix metalloproteinase-2 ablation in dystrophin-deficient mdx muscles reduces angiogenesis resulting in impaired growth of regenerated muscle fibers.

    PubMed

    Miyazaki, Daigo; Nakamura, Akinori; Fukushima, Kazuhiro; Yoshida, Kunihiro; Takeda, Shin'ichi; Ikeda, Shu-ichi

    2011-05-01

    Matrix metalloproteases (MMPs) are a family of endopeptidases classified into subgroups based on substrate preference in normal physiological processes such as embryonic development and tissue remodeling, as well as in various disease processes via degradation of extracellular matrix components. Among the MMPs, MMP-9 and MMP-2 have been reported to be up-regulated in skeletal muscles in the lethal X-linked muscle disorder Duchenne muscular dystrophy (DMD), which is caused by loss of dystrophin. A recent study showed that deletion of the MMP9 gene in mdx, a mouse model for DMD, improved skeletal muscle pathology and function; however, the role of MMP-2 in the dystrophin-deficient muscle is not well known. In this study, we aimed at verifying the role of MMP-2 in the dystrophin-deficient muscle by using mdx mice with genetic ablation of MMP-2 (mdx/MMP-2(-/-)). We found impairment of regenerated muscle fiber growth with reduction of angiogenesis in mdx/MMP-2(-/-) mice at 3 months of age. Expression of vascular endothelial growth factor-A (VEGF-A), an important angiogenesis-related factor, decreased in mdx/MMP-2(-/-) mice at 3 months of age. MMP-2 had not a critical role in the degradation of dystrophin-glycoprotein complex (DGC) components such as β-dystroglycan and β-sarcoglycan in the regeneration process of the dystrophic muscle. Accordingly, MMP-2 may be essential for growth of regenerated muscle fibers through VEGF-associated angiogenesis in the dystrophin-deficient skeletal muscle.

  18. Muscle Arnt/Hif1β Is Dispensable in Myofiber Type Determination, Vascularization and Insulin Sensitivity.

    PubMed

    Badin, Pierre-Marie; Sopariwala, Danesh H; Lorca, Sabina; Narkar, Vihang A

    2016-01-01

    Aryl Hydrocarbon Receptor Nuclear Translocator/ hypoxia-inducible factor 1 beta (ARNT/ HIF1β), a member of bHLH-PAS family of transcriptional factors, plays a critical role in metabolic homeostasis, insulin resistance and glucose intolerance. The contributions of ARNT in pancreas, liver and adipose tissue to energy balance through gene regulation have been described. Surprisingly, the impact of ARNT signaling in the skeletal muscles, one of the major organs involved in glucose disposal, has not been investigated, especially in type II diabetes. Here we report that ARNT is expressed in the skeletal muscles, particularly in the energy-efficient oxidative slow-twitch myofibers, which are characterized by increased oxidative capacity, mitochondrial content, vascular supply and insulin sensitivity. However, muscle-specific deletion of ARNT did not change myofiber type distribution, oxidative capacity, mitochondrial content, capillarity, or the expression of genes associated with these features. Consequently, the lack of ARNT in the skeletal muscle did not affect weight gain, lean/fat mass, insulin sensitivity and glucose tolerance in lean mice, nor did it impact insulin resistance and glucose intolerance in high fat diet-induced obesity. Therefore, skeletal muscle ARNT is dispensable for controlling muscle fiber type and metabolic regulation, as well as diet-induced weight control, insulin sensitivity and glucose tolerance.

  19. Muscle Arnt/Hif1β Is Dispensable in Myofiber Type Determination, Vascularization and Insulin Sensitivity

    PubMed Central

    Badin, Pierre-Marie; Sopariwala, Danesh H.; Lorca, Sabina

    2016-01-01

    Aryl Hydrocarbon Receptor Nuclear Translocator/ hypoxia-inducible factor 1 beta (ARNT/ HIF1β), a member of bHLH-PAS family of transcriptional factors, plays a critical role in metabolic homeostasis, insulin resistance and glucose intolerance. The contributions of ARNT in pancreas, liver and adipose tissue to energy balance through gene regulation have been described. Surprisingly, the impact of ARNT signaling in the skeletal muscles, one of the major organs involved in glucose disposal, has not been investigated, especially in type II diabetes. Here we report that ARNT is expressed in the skeletal muscles, particularly in the energy-efficient oxidative slow-twitch myofibers, which are characterized by increased oxidative capacity, mitochondrial content, vascular supply and insulin sensitivity. However, muscle-specific deletion of ARNT did not change myofiber type distribution, oxidative capacity, mitochondrial content, capillarity, or the expression of genes associated with these features. Consequently, the lack of ARNT in the skeletal muscle did not affect weight gain, lean/fat mass, insulin sensitivity and glucose tolerance in lean mice, nor did it impact insulin resistance and glucose intolerance in high fat diet-induced obesity. Therefore, skeletal muscle ARNT is dispensable for controlling muscle fiber type and metabolic regulation, as well as diet-induced weight control, insulin sensitivity and glucose tolerance. PMID:28005939

  20. PGC-1α is important for maintaining the balance of muscle mass and myofiber types in unloaded muscle atrophy

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoping; He, Jian; Wang, Fei; Zhang, Peng; Liu, Hongju; Li, Wenjiong

    2016-07-01

    maintaining the balance of muscle mass and myofiber type MHCs in unloaded muscle atrophy via suppressing Smad3 activation. This report may prompt a hopeful therapeutic strategy for maintaining muscle mass and fiber type composition in disused muscle atrophies such as space weightlessness- or immobilization-induced muscle atrophy. Acknowledgments This work was supported by the Natural Sciences Foundation of China (31171144, 81272177 and 31171148), the State Key Laboratory Grant of Space Medicine Fundamentals and Application (SMFA13A01), and the National Key Laboratory Grant of Human Factors Engineering (SYFD140051801).

  1. Muscle cell membranes from early degeneration muscle cell fibers in Solenopsis are leaky to lanthanum: electron microscopy and X-ray analysis

    SciTech Connect

    Jones, R.G.; Davis, W.L.

    1985-06-01

    Lanthanum infusion techniques, transmission electron microscopy, and X-ray microanalysis were utilized to compare the permeability of muscle cell membranes from normal and degenerating muscle fibers of Solenopsis spp. In normal fibers, the electron-dense tracer was limited to components of the sarcotubular system. However, the insemination-induced degeneration of muscle fibers was characterized by the presence of an electron-dense precipitate within the myofibrils and mitochondria as well as in the extramyofibrillar spaces. The electron-dense material was subsequently identified by elemental analysis to be lanthanum. Such data indicate that one of the earliest stages of muscle degeneration involves an alteration in cell membrane permeability.

  2. Magnetic field of a single muscle fiber. First measurements and a core conductor model.

    PubMed Central

    van Egeraat, J M; Friedman, R N; Wikswo, J P

    1990-01-01

    We present the first measurements of the magnetic field from a single muscle fiber of the frog gastrocnemius, obtained by using a toroidal pickup coil coupled to a room-temperature, low-noise amplifier. The axial currents associated with the magnetic fields of single fibers were biphasic and had peak-to-peak amplitudes ranging between 50 and 100 nA, depending primarily on the fiber radius. With an intracellular microelectrode, we measured the action potential of the same fiber, which allowed us to determine that the intracellular conductivity of the muscle fiber in the core conductor approximation was 0.20 +/- 0.09 S/m. Similarly, we found that the effective membrane capacitance was 0.030 +/- 0.011 F/m2. These results were not significantly affected by the anisotropic conductivity of the muscle bundle. We demonstrate how our magnetic technique can be used to determine the transmembrane action potential without penetrating the membrane with a microelectrode, thereby offering a reliable, stable, and atraumatic method for studying contracting muscle fibers. PMID:2306511

  3. New function of the myostatin/activin type I receptor (ALK4) as a mediator of muscle atrophy and muscle regeneration

    PubMed Central

    Pasteuning-Vuhman, Svitlana; Boertje-van der Meulen, Johanna W.; van Putten, Maaike; Overzier, Maurice; ten Dijke, Peter; Kiełbasa, Szymon M.; Arindrarto, Wibowo; Wolterbeek, Ron; Lezhnina, Ksenia V.; Ozerov, Ivan V.; Aliper, Aleksandr M.; Hoogaars, Willem M.; Aartsma-Rus, Annemieke; Loomans, Cindy J. M.

    2017-01-01

    Skeletal muscle fibrosis and impaired muscle regeneration are major contributors to muscle wasting in Duchenne muscular dystrophy (DMD). Muscle growth is negatively regulated by myostatin (MSTN) and activins. Blockage of these pathways may improve muscle quality and function in DMD. Antisense oligonucleotides (AONs) were designed specifically to block the function of ALK4, a key receptor for the MSTN/activin pathway in skeletal muscle. AON-induced exon skipping resulted in specific Alk4 down-regulation, inhibition of MSTN activity, and increased myoblast differentiation in vitro. Unexpectedly, a marked decrease in muscle mass (10%) was found after Alk4 AON treatment in mdx mice. In line with in vitro results, muscle regeneration was stimulated, and muscle fiber size decreased markedly. Notably, when Alk4 was down-regulated in adult wild-type mice, muscle mass decreased even more. RNAseq analysis revealed dysregulated metabolic functions and signs of muscle atrophy. We conclude that ALK4 inhibition increases myogenesis but also regulates the tight balance of protein synthesis and degradation. Therefore, caution must be used when developing therapies that interfere with MSTN/activin pathways.—Pasteuning-Vuhman, S., Boertje-van der Meulen, J. W., van Putten, M., Overzier, M., ten Dijke, P., Kiełbasa, S. M., Arindrarto, W., Wolterbeek, R., Lezhnina, K. V., Ozerov, I. V., Aliper, A. M., Hoogaars, W. M., Aartsma-Rus, A., Loomans, C. J. M. New function of the myostatin/activin type I receptor (ALK4) as a mediator of muscle atrophy and muscle regeneration. PMID:27733450

  4. Highly Conductive Graphene/Ag Hybrid Fibers for Flexible Fiber-Type Transistors

    PubMed Central

    Yoon, Sang Su; Lee, Kang Eun; Cha, Hwa-Jin; Seong, Dong Gi; Um, Moon-Kwang; Byun, Joon-Hyung; Oh, Youngseok; Oh, Joon Hak; Lee, Wonoh; Lee, Jea Uk

    2015-01-01

    Mechanically robust, flexible, and electrically conductive textiles are highly suitable for use in wearable electronic applications. In this study, highly conductive and flexible graphene/Ag hybrid fibers were prepared and used as electrodes for planar and fiber-type transistors. The graphene/Ag hybrid fibers were fabricated by the wet-spinning/drawing of giant graphene oxide and subsequent functionalization with Ag nanoparticles. The graphene/Ag hybrid fibers exhibited record-high electrical conductivity of up to 15,800 S cm−1. As the graphene/Ag hybrid fibers can be easily cut and placed onto flexible substrates by simply gluing or stitching, ion gel-gated planar transistors were fabricated by using the hybrid fibers as source, drain, and gate electrodes. Finally, fiber-type transistors were constructed by embedding the graphene/Ag hybrid fiber electrodes onto conventional polyurethane monofilaments, which exhibited excellent flexibility (highly bendable and rollable properties), high electrical performance (μh = 15.6 cm2 V−1 s−1, Ion/Ioff > 104), and outstanding device performance stability (stable after 1,000 cycles of bending tests and being exposed for 30 days to ambient conditions). We believe that our simple methods for the fabrication of graphene/Ag hybrid fiber electrodes for use in fiber-type transistors can potentially be applied to the development all-organic wearable devices. PMID:26549711

  5. Micromechanical behavior of single-fiber type and hybrid microcomposites

    SciTech Connect

    Qiu Yiping.

    1992-01-01

    Single-fiber type and hybrid microcomposites were fabricated using Kevlar {reg sign} 149 as the low elongation (LE) fiber and S-glass fibers as the high elongation fiber using a DER 331/DER 732 epoxy mixture (70/30, w/w). In tensile tests, it was found that Kevlar{reg sign} 149 fiber was significantly stronger in the microcomposite than as a single filament. For the hybrid microcomposite, Kevlar{reg sign} 149 fibers usually broke one by one. A positive hybrid effect for the failure strain but a negative hybrid effect for the strength of the hybrid were observed. The tensile modulus of the hybrid microcomposite followed the rule of mixtures well. The fiber/matrix interface properties were investigated using the single-fiber pull-out from a microcomposite (SFPOM) test and the microbond test. SFPOM test reflected the feeling of the fibers in a real composite, showing the decrease of interfacial shear strength (IFSS) with fiber volume fraction increase. To predict the stress-rupture lifetime of a hybrid composite, a stochastic model was proposed assuming that the failure of LE fibers in a hybrid follows a continuous time Markov chain.

  6. Characterization of lobulated fibers in limb girdle muscular dystrophy type 2A by gene expression profiling.

    PubMed

    Keira, Yoko; Noguchi, Satoru; Kurokawa, Rumi; Fujita, Masako; Minami, Narihiro; Hayashi, Yukiko K; Kato, Takashi; Nishino, Ichizo

    2007-04-01

    Limb girdle muscular dystrophy type 2A (LGMD2A) is caused by mutations in CAPN3, which encodes an intracellular cysteine protease. To elucidate the fundamental molecular changes that may be responsible for the pathological features of LGMD2A, we employed cDNA microarray analysis. We divided LGMD2A muscles into two groups according to specific pathological features: an early-stage group characterized by the presence of active necrosis and a regeneration process and a later-stage group characterized by the presence of lobulated fibers. After comparing the gene expression profiles of the two groups of LGMD2A muscles with control muscles, we identified 29 genes whose mRNA expression profiles were specifically altered in muscles with lobulated fibers. Interestingly, this group included genes that encode actin filament binding and regulatory proteins, such as gelsolin, PDZ and LIM domain 3 (PDLIM3) and troponin I1. Western blot analysis confirmed the upregulation of these proteins. From these results, we propose that abnormal increased expression of actin filament binding proteins may contribute to the changes of the intra-myofiber structures, observed in lobulated fibers in LGMD2A.

  7. Inorganic Nitrate Mimics Exercise-Stimulated Muscular Fiber-Type Switching and Myokine and γ-Aminobutyric Acid Release.

    PubMed

    Roberts, Lee D; Ashmore, Tom; McNally, Ben D; Murfitt, Steven A; Fernandez, Bernadette O; Feelisch, Martin; Lindsay, Ross; Siervo, Mario; Williams, Elizabeth A; Murray, Andrew J; Griffin, Julian L

    2017-03-01

    Exercise is an effective intervention for the prevention and treatment of type 2 diabetes. Skeletal muscle combines multiple signals that contribute to the beneficial effects of exercise on cardiometabolic health. Inorganic nitrate increases exercise efficiency, tolerance, and performance. The transcriptional regulator peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) coordinates the exercise-stimulated skeletal muscle fiber-type switch from glycolytic fast-twitch (type IIb) to oxidative slow-twitch (type I) and intermediate (type IIa) fibers, an effect reversed in insulin resistance and diabetes. We found that nitrate induces PGC1α expression and a switch toward type I and IIa fibers in rat muscle and myotubes in vitro. Nitrate induces the release of exercise/PGC1α-dependent myokine FNDC5/irisin and β-aminoisobutyric acid from myotubes and muscle in rats and humans. Both exercise and nitrate stimulated PGC1α-mediated γ-aminobutyric acid (GABA) secretion from muscle. Circulating GABA concentrations were increased in exercising mice and nitrate-treated rats and humans; thus, GABA may function as an exercise/PGC1α-mediated myokine-like small molecule. Moreover, nitrate increased circulating growth hormone levels in humans and rodents. Nitrate induces physiological responses that mimic exercise training and may underlie the beneficial effects of this metabolite on exercise and cardiometabolic health.

  8. Single fiber, laser Doppler flowmetry (LDF) for detecting muscle microcirculation in the low leg and its technique improvement

    NASA Astrophysics Data System (ADS)

    Cai, Hongming; Oberg, P. Ake; Rohman, Hakan; Larsson, Sven-Erik

    1995-02-01

    Percutaneous, single fiber LDF of 632.8 nm (He-Ne) is used for continuous recording of low leg muscle microcirculation. An optical fiber (0 equals 0.5 mm) was placed inside the tibialis ant. muscle 10 cm below the knee joint via a plastic cannula (0 equals 1.0 mm) and using local anaesthesia of the skin. The LDF is sampled continuously by the on-line PC computer one minute before, three minutes during and for four minutes after tourniquet occlusion. Twelve healthy, non-smoking men were examined. The reactive hyperaemia and the flux reactive time after release of tourniquet was examined successfully. To get better signal-to-noise ration and deeper detected volume in the muscle, the optical characteristics of ordinary fiber tips and modified spherical and `pear'-type ends were studied. Compared with the system of 632.8 nm, a new optical system with a laser diode of 790 nm was developed. A PC computer with DSP card was used for all the signal processing in the new system.

  9. AHNAK1 and AHNAK2 are costameric proteins: AHNAK1 affects transverse skeletal muscle fiber stiffness

    SciTech Connect

    Marg, Andreas; Haase, Hannelore; Neumann, Tanja; Kouno, Michiyoshi; Morano, Ingo

    2010-10-08

    Research highlights: {yields} AHNAK1 and AHNAK2 are costameric proteins. {yields} Intact membrane repair in AHNAK1-deficient mice. {yields} AHNAK1{sup -/-} single fibers have a higher transverse stiffness. -- Abstract: The AHNAK scaffold PDZ-protein family is implicated in various cellular processes including membrane repair; however, AHNAK function and subcellular localization in skeletal muscle are unclear. We used specific AHNAK1 and AHNAK2 antibodies to analyzed the detailed localization of both proteins in mouse skeletal muscle. Co-localization of AHNAK1 and AHNAK2 with vinculin clearly demonstrates that both proteins are components of the costameric network. In contrast, no AHNAK expression was detected in the T-tubule system. A laser wounding assay with AHNAK1-deficient fibers suggests that AHNAK1 is not involved in membrane repair. Using atomic force microscopy (AFM), we observed a significantly higher transverse stiffness of AHNAK1{sup -/-} fibers. These findings suggest novel functions of AHNAK proteins in skeletal muscle.

  10. Expansion of revertant fibers in dystrophic mdx muscles reflects activity of muscle precursor cells and serves as an index of muscle regeneration.

    PubMed

    Yokota, Toshifumi; Lu, Qi-Long; Morgan, Jennifer E; Davies, Kay E; Fisher, Rosie; Takeda, Shin'ichi; Partridge, Terence A

    2006-07-01

    Duchenne muscular dystrophy and the mdx mouse myopathies reflect a lack of dystrophin in muscles. However, both contain sporadic clusters of revertant fibers (RFs) that express dystrophin. RF clusters expand in size with age in mdx mice. To test the hypothesis that the expansion of clusters is achieved through the process of muscle degeneration and regeneration, we analyzed muscles of mdx mice in which degeneration and regeneration were inhibited by the expression of micro-dystrophins or utrophin transgenes. Postnatal RF expansion was diminished in direct correlation to the protective effect of the transgene expression. Similarly, expansion of RFs was inhibited when muscle regeneration was blocked by irradiation. However, in irradiated muscles, irradiation-tolerant quiescent muscle precursor cells reactivated by notexin effectively restored RF expansion. Our observations demonstrate that revertant events occur initially within a subset of muscle precursor cells. The proliferation of these cells, as part of the regeneration process, leads to the expansion of RF clusters within degenerating muscles. This expansion of revertant clusters depicts the cumulative history of regeneration, thus providing a useful index for functional evaluation of therapies that counteract muscle degeneration.

  11. Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles

    NASA Astrophysics Data System (ADS)

    Liu, Z. F.; Fang, S.; Moura, F. A.; Ding, J. N.; Jiang, N.; Di, J.; Zhang, M.; Lepró, X.; Galvão, D. S.; Haines, C. S.; Yuan, N. Y.; Yin, S. G.; Lee, D. W.; Wang, R.; Wang, H. Y.; Lv, W.; Dong, C.; Zhang, R. C.; Chen, M. J.; Yin, Q.; Chong, Y. T.; Zhang, R.; Wang, X.; Lima, M. D.; Ovalle-Robles, R.; Qian, D.; Lu, H.; Baughman, R. H.

    2015-07-01

    Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson’s ratio on torsional actuation and electronic properties.

  12. STRETCHY ELECTRONICS. Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles.

    PubMed

    Liu, Z F; Fang, S; Moura, F A; Ding, J N; Jiang, N; Di, J; Zhang, M; Lepró, X; Galvão, D S; Haines, C S; Yuan, N Y; Yin, S G; Lee, D W; Wang, R; Wang, H Y; Lv, W; Dong, C; Zhang, R C; Chen, M J; Yin, Q; Chong, Y T; Zhang, R; Wang, X; Lima, M D; Ovalle-Robles, R; Qian, D; Lu, H; Baughman, R H

    2015-07-24

    Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.

  13. Peeled mammalian skeletal muscle fibers. Possible stimulation of Ca2+ release via a transverse tubule-sarcoplasmic reticulum mechanism

    PubMed Central

    1985-01-01

    Single muscle fibers from rabbit soleus and adductor magnus and from semitendinosus muscles were peeled to remove the sarcolemma and then stimulated to release Ca2+ by (a) caffeine application or (b) ionic depolarization accomplished via substitution of choline chloride for potassium propionate at constant [K+] X [Cl-] in the bathing solution. Each stimulus, ionic or caffeine, elicited an isometric tension transient that appeared to be due to Ca2+ released from the sarcoplasmic reticulum (SR). The peak magnitude of the ionic (Cl- - induced) tension transient increased with increasing Cl- concentration. The application of ouabain to fibers after peeling had no effect on either type of tension transient. However, soaking the fibers in a ouabain solution before peeling blocked the Cl- -induced but not the caffeine-induced tension transient, which suggests that ouabain's site of action is extracellular, perhaps inside transverse tubules (TTs). Treating the peeled fibers with saponin, which should disrupt TTs to a greater extent than SR membrane, greatly reduced or eliminated the Cl- - induced tension transient without significantly altering the caffeine- induced tension transient. These results suggest that the Cl- -induced tension transient is elicited via stimulation of sealed, polarized TTs rather than via ionic depolarization of the SR. PMID:4056734

  14. In situ cross-linked electrospun fiber scaffold of collagen for fabricating cell-dense muscle tissue.

    PubMed

    Takeda, Naoya; Tamura, Kenichi; Mineguchi, Ryo; Ishikawa, Yumiko; Haraguchi, Yuji; Shimizu, Tatsuya; Hara, Yusuke

    2016-06-01

    Engineered muscle tissues used as transplant tissues in regenerative medicine should have a three-dimensional and cell-dense structure like native tissue. For fabricating a 3D cell-dense muscle tissue from myoblasts, we proposed the electrospun type I collagen microfiber scaffold of the string-shape like a harp. The microfibers were oriented in the same direction to allow the myoblasts to align, and were strung at low density with micrometer intervals to create space for the cells to occupy. To realize this shape of the scaffold, we employed in situ cross-linking during electrospinning process for the first time to collagen fibers. The collagen microfibers in situ cross-linked with glutaraldehyde stably existed in the aqueous media and completely retained the original shape to save the spaces between the fibers for over 14 days. On the contrary, the conventional cross-linking method by exposure to a glutaraldehyde aqueous solution vapor partially dissolved and damaged the fiber to lose a low-density shape of the scaffold. Myoblasts could penetrate into the interior of the in situ cross-linked string-shaped scaffold and form the cell-dense muscle tissues. Histochemical analysis showed the total area occupied by the cells in the cross section of the tissue was approximately 73 %. Furthermore, the resulting muscle tissue fabricated from primary myoblasts showed typical sarcomeric cross-striations and the entire tissue continuously pulsated by autonomous contraction. Together with the in situ cross-linking, the string-shaped scaffold provides an efficient methodology to fabricate a cell-dense 3D muscle tissue, which could be applied in regenerative medicine in future.

  15. Measurement of sarcomere shortening in skinned fibers from frog muscle by white light diffraction.

    PubMed Central

    Goldman, Y E

    1987-01-01

    A new optical-electronic method has been developed to detect striation spacing of single muscle fibers. The technique avoids Bragg-angle and interference-fringe effects associated with laser light diffraction by using polychromatic (white) light. The light is diffracted once by an acousto-optical device and then diffracted again by the muscle fiber. The double diffraction reverses the chromatic dispersion normally obtained with polychromatic light. In frog skinned muscle fibers, active and passive sarcomere shortening were smooth when observed by white light diffraction, whereas steps and pauses occurred in the striation spacing signals obtained with laser illumination. During active contractions skinned fibers shortened at high rates (3-5 microns/s per half sarcomere, 0-5 degrees C) at loads below 5% of isometric tension. Compression of the myofibrillar lateral filament spacing using osmotic agents reduced the shortening velocity at low loads. A hypothesis is presented that high shortening velocities are observed with skinned muscle fibers because the cross-bridges cannot support compressive loads when the filament lattice is swollen. Images FIGURE 2 PMID:3496924

  16. Effect of extracellular potassium accumulation on muscle fiber conduction velocity: a simulation study.

    PubMed

    Fortune, Emma; Lowery, Madeleine M

    2009-10-01

    A progressive reduction in muscle fiber conduction velocity is typically observed during fatiguing muscle contraction. Although the exact causes of the conduction velocity decrease have not yet been fully established, increasing evidence suggests that changes in extracellular potassium concentration may be largely responsible. In this study, a mathematical model was developed to examine the effect of extracellular potassium concentration on the muscle fiber action potential and conduction velocity. The model was used to simulate changes in extracellular potassium concentration at a range of temperatures and extracellular potassium accumulation during repetitive stimulation of the muscle fiber at 37 degrees C. The action potential broadened, and its amplitude and conduction velocity decreased as extracellular potassium concentration increased. The potassium-induced changes in action potential shape and conduction velocity were eliminated when the inward rectifier channels were removed from the model. The results support the hypothesis that accumulation of extracellular potassium ions may be a major contributor to the reduction in muscle fiber conduction velocity and loss of membrane excitability during fatiguing contractions. They additionally suggest that inward rectifier currents play a critical role in potassium-induced membrane depolarization, leading to increased sodium inactivation and resulting in the observed reduction in conduction velocity and membrane excitability.

  17. [Contractile properties of fibers and cytoskeletal proteins of gerbil's hindlimb muscles after space flight].

    PubMed

    Lipets, E N; Ponomareva, E V; Ogneva, I V; Vikhliantsev, I M; Karaduleva, E V; Kratashkina, N L; Kuznetsov, S L; Podlubnaia, Z A; Shenkman, B S

    2009-01-01

    The work had the goal to compare the microgravity effects on gerbil's muscles-antagonists, m. soleus and m. tibialis anterior. The animals were exposed in 12-d space microgravity aboard Earth's artificial satellite "Foton-M3". Findings of the analysis of single skinned fibers contractility are 19.7% diminution of the diameter and 21.8% loss of the total contractive force of m. soleus fibers post flight. However, there was no significant difference in calcium sensitivity which agrees with the absence of changes in the relative content of several major cytoskeletal proteins (titin and nebulin ratios to heavy chains of myosin were identical in the flight and control groups) and a slight shifting of the myosin phenotype toward the "fast type" (9%, p < 0.05). These parameters were mostly unaffected by the space flight in m. tibialis anterior. To sum up, the decline of contractility and diminution of gerbil's myofibers after the space flight were less significant as compared with rats and did not impact the sytoskeletal protein ratios.

  18. Extraction and functional reformation of thick filaments in chemically skinned molluscan catch muscle fibers.

    PubMed

    Tanaka, M; Tanaka, H

    1979-02-01

    A method for the almost complete extraction of myosin from smooth muscle fibers of the anterior byssal retractor muscle (ABRM) of Mytilus edulis was developed, and functional reformation of thick filaments in the fibers was achieved. Complete removal of myosin from the glycerol-extracted ABRM fibers with a solution containing 600 mM KCl, 5 mM MgCl2, and 5 mM ATP was difficult. However, successive treatments of the ABRM fibers with glycerol and saponin made the plasma membrane permeable to Mg-ATP and myosin. The extraction of myosin completely eliminated the tension induced by the addition of Mg-ATP. Partial recovery of tension development was observed by irrigation of myosin into fibers from which myosin had been extracted. Similar results were obtained using rabbit myosin instead of ABRM myosin. Addition of heavy meromyosin, on the other hand, had a suppressive effect on the tension development, as is the case in glycerinated rabbit psoas muscle fibers.

  19. Pointed-end capping by tropomodulin modulates actomyosin crossbridge formation in skeletal muscle fibers

    PubMed Central

    Ochala, Julien; Gokhin, David S.; Iwamoto, Hiroyuki; Fowler, Velia M.

    2014-01-01

    In skeletal muscle, thick and thin filaments are arranged in a myofibrillar lattice. Tropomodulin 1 (Tmod1) is a pointed-end capping and tropomyosin-binding protein that controls thin-filament assembly, stability, and lengths. It remains unknown whether Tmods have other functional roles, such as regulating muscle contractility. To investigate this, we recorded and analyzed the mechanical properties and X-ray diffraction patterns of single membrane-permeabilized skeletal muscle fibers from mice lacking Tmod1. Results show that absence of Tmod1 and its replacement by Tmod3 and Tmod4 may impair initial tropomyosin movement over actin subunits during thin-filament activation, thus reducing both the fraction of actomyosin crossbridges in the strongly bound state (−29%) and fiber force-generating capacity (−31%). Therefore, Tmods are novel regulators of actomyosin crossbridge formation and muscle contractility, and future investigations and models of skeletal muscle force production must incorporate Tmods.—Ochala, J., Gokhin, D. S., Iwamoto, H., Fowler, V. M. Pointed-end capping by tropomodulin modulates actomyosin crossbridge formation in skeletal muscle fibers. PMID:24072783

  20. Functional imaging of skeletal muscle fiber in different physiological states by second harmonic generation

    NASA Astrophysics Data System (ADS)

    Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Tesi, C.; Piroddi, N.; Poggesi, C.; Castiglioni, C.; Milani, A.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

    2007-07-01

    The intrinsically ordered arrays of proteins in skeletal muscle allows imaging of this tissue by Second Harmonic Generation (SHG). Biochemical and colocalization studies have gathered an increasing wealth of clues for the attribution of the molecular origin of the muscle SHG signal to the motor protein myosin. Thus, SHG represents a potentially very powerful tool in the investigation of structural dynamics occurring in muscle during active production of force. A full characterization of the polarization-dependence of the SHG signal represents a very selective information on the orientation of the emitting proteins and their dynamics during contraction, provided that different physiological states of muscle (relaxed, rigor and active) exhibit distinct patterns of SHG polarization dependence. Here polarization data are obtained from single frog muscle fibers at rest and during isometric contraction and interpreted, by means of a model, in terms of an average orientation of the SHG emitters which are structured with a cylindrical symmetry about the fiber axis. Optimizing the setup for accurate polarization measurements with SHG, we developed a line scan imaging method allowing measurement of SHG polarization curves in different physiological states. We demonstrate that muscle fiber displays a measurable variation of the orientation of SHG emitters with the transition from rest to isometric contraction.

  1. Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

    PubMed

    Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

  2. Smooth Muscle-Like Tissue Constructs with Circumferentially Oriented Cells Formed by the Cell Fiber Technology

    PubMed Central

    Hsiao, Amy Y.; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments. PMID:25734774

  3. Abcg2 labels multiple cell types in skeletal muscle and participates in muscle regeneration

    PubMed Central

    Doyle, Michelle J.; Zhou, Sheng; Tanaka, Kathleen Kelly; Pisconti, Addolorata; Farina, Nicholas H.; Sorrentino, Brian P.

    2011-01-01

    Skeletal muscle contains progenitor cells (satellite cells) that maintain and repair muscle. It also contains muscle side population (SP) cells, which express Abcg2 and may participate in muscle regeneration or may represent a source of satellite cell replenishment. In Abcg2-null mice, the SP fraction is lost in skeletal muscle, although the significance of this loss was previously unknown. We show that cells expressing Abcg2 increased upon injury and that muscle regeneration was impaired in Abcg2-null mice, resulting in fewer centrally nucleated myofibers, reduced myofiber size, and fewer satellite cells. Additionally, using genetic lineage tracing, we demonstrate that the progeny of Abcg2-expressing cells contributed to multiple cell types within the muscle interstitium, primarily endothelial cells. After injury, Abcg2 progeny made a minor contribution to regenerated myofibers. Furthermore, Abcg2-labeled cells increased significantly upon injury and appeared to traffic to muscle from peripheral blood. Together, these data suggest an important role for Abcg2 in positively regulating skeletal muscle regeneration. PMID:21949413

  4. Relationship between function of masticatory muscle in mouse and properties of muscle fibers.

    PubMed

    Abe, Shinichi; Hiroki, Emi; Iwanuma, Osamu; Sakiyama, Koji; Shirakura, Yoshitaka; Hirose, Daiki; Shimoo, Yoshiaki; Suzuki, Masashi; Ikari, Yasutoyo; Kikuchi, Ryusuke; Ide, Yoshinobu; Yoshinari, Masao

    2008-05-01

    Mammals exhibit marked morphological differences in the muscles surrounding the jaw bone due to differences in eating habits. Furthermore, the myofiber properties of the muscles differ with function. Since the muscles in the oral region have various functions such as eating, swallowing, and speech, it is believed that the functional role of each muscle differs. Therefore, to clarify the functional role of each masticatory muscle, the myofiber properties of the adult mouse masticatory muscles were investigated at the transcriptional level. Expression of MyHC-2b with a fast contraction rate and strong force was frequently noted in the temporal and masseter muscles. This suggests that the temporal and masseter muscles are closely involved in rapid antero-posterior masticatory movement, which is characteristic in mice. Furthermore, expression of MyHC-1 with a low contraction rate and weak continuous force was frequently detected in the lateral pterygoid muscle. This suggests that, in contrast to other masticatory muscles, mouse lateral pterygoid muscle is not involved in fast masticatory movement, but is involved in functions requiring continuous force such as retention of jaw position. This study revealed that muscles with different roles function comprehensively during complicated masticatory movement.

  5. Muscle fibre types of the lumbrical, interossei, flexor, and extensor muscles moving the index finger.

    PubMed

    Hwang, Kun; Huan, Fan; Kim, Dae Joong

    2013-09-01

    The aim of this study was to determine the fibre types of the muscles moving the index fingers in humans. Fifteen forearms of eight adult cadavers were used. The sampled muscles were the first lumbrical (LM), first volar interosseous (VI), first dorsal interosseus (DI), second flexor digitorum profundus (FDP), second flexor digitorum superficialis (FDS), and extensor digitorum (ED). Six micrometer thick sections were stained for fast muscle fibres. The procedure was performed by applying mouse monoclonal anti-skeletal myosin antibody (fast) and avidin-biotin peroxidase complex staining. Rectangular areas (0.38 mm × 0.38 mm) were photographed and the boundaries of the muscle areas were marked on the translucent film. The numbers and sizes of the muscle fibres in each part were evaluated by the image analyser program and calculated per unit area (1 mm(2)). The proportion of the fast fibres was significantly (p = 0.012) greater in the intrinsic muscles (55.7 ± 17.1%) than in the extrinsic muscles (45.9 ± 17.1%). Among the six muscles, the VI had a significantly higher portion (59.3%) of fast fibres than the FDS (40.6%) (p = 0.005) or the FDP (45.1%) (p = 0.023). The density of the non-fast fibres was significantly (p = 0.015) greater in the extrinsic muscles (539.2 ± 336.8/mm(2)) than in the intrinsic muscles (383.4 ± 230.4/mm2). Since the non-fast fibres represent less fatigable fibres, it is thought that the extrinsic muscles have higher durability against fatigue, and the intrinsic muscles, including the LM, should move faster than the FDS or FDP because the MP joint should be flexed before the IP joint to grip an object.

  6. Injection of duck recombinant follistatin fusion protein into duck muscle tissues stimulates satellite cell proliferation and muscle fiber hypertrophy.

    PubMed

    Liu, He-he; Wang, Ji-wen; Yu, Hai-yue; Zhang, Rong-ping; Chen, Xi; Jin, Hai-bo; Dai, Fei; Li, Liang; Xu, Feng

    2012-06-01

    Follistatin (FST) can inhibit the expression of myostatin, which is a predominant inhibitor of muscle development. The potential application of myostatin-based technology has been prompted in different ways in agriculture. We previously constructed an expression vector of duck FST and isolated the FST fusion protein. After the protein was purified and refolded, it was added to the medium of duck myoblasts cultured in vitro. The results show that the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide value of the myoblasts in the duck FST treatment group is higher than that in the control group, which indicates that the duck FST fusion protein exhibits the biological activities that can accelerate myoblast proliferation. To further investigate the roles of duck FST on muscle development, we injected the protein into the duck muscle ti