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slow and fast twitch muscle fibers and activity

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https://www.readbyqxmd.com/read/29780328/contractile-activity-is-necessary-to-trigger-intermittent-hypobaric-hypoxia-induced-fiber-size-and-vascular-adaptations-in-skeletal-muscle
#1
David Rizo-Roca, Jèssica B Bonet, Büsra Ínal, Juan Gabriel Ríos-Kristjánsson, Teresa Pagès, Ginés Viscor, Joan R Torrella
Altitude training has become increasingly popular in recent decades. Its central and peripheral effects are well-described; however, few studies have analyzed the effects of intermittent hypobaric hypoxia (IHH) alone on skeletal muscle morphofunctionality. Here, we studied the effects of IHH on different myofiber morphofunctional parameters, investigating whether contractile activity is required to elicit hypoxia-induced adaptations in trained rats. Eighteen male Sprague-Dawley rats were trained 1 month and then divided into three groups: (1) rats in normobaria (trained normobaric inactive, TNI); (2) rats subjected daily to a 4-h exposure to hypobaric hypoxia equivalent to 4,000 m (trained hypobaric inactive, THI); and (3) rats subjected daily to a 4-h exposure to hypobaric hypoxia just before performing light exercise (trained hypobaric active, THA)...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29768191/loss-of-a-negative-regulator-of-mtorc1-induces-aerobic-glycolysis-and-altered-fiber-composition-in-skeletal-muscle
#2
Paul A Dutchak, Sandi J Estill-Terpack, Abigail A Plec, Xiaozheng Zhao, Chendong Yang, Jun Chen, Bookyung Ko, Ralph J Deberardinis, Yonghao Yu, Benjamin P Tu
The conserved GATOR1 complex consisting of NPRL2-NPRL3-DEPDC5 inhibits mammalian target of rapamycin complex 1 (mTORC1) in response to amino acid insufficiency. Here, we show that loss of NPRL2 and GATOR1 function in skeletal muscle causes constitutive activation of mTORC1 signaling in the fed and fasted states. Muscle fibers of NPRL2 knockout animals are significantly larger and show altered fiber-type composition, with more fast-twitch glycolytic and fewer slow-twitch oxidative fibers. NPRL2 muscle knockout mice also have altered running behavior and enhanced glucose tolerance...
May 15, 2018: Cell Reports
https://www.readbyqxmd.com/read/29684379/effect-of-a-long-term-treatment-with-metformin-in-dystrophic-mdx-mice-a-reconsideration-of-its-potential-clinical-interest-in-duchenne-muscular-dystrophy
#3
Paola Mantuano, Francesca Sanarica, Elena Conte, Maria Grazia Morgese, Roberta Francesca Capogrosso, Anna Cozzoli, Adriano Fonzino, Angelo Quaranta, Jean-Francois Rolland, Michela De Bellis, Giulia Maria Camerino, Luigia Trabace, Annamaria De Luca
The pharmacological stimulation of AMP-activated protein kinase (AMPK) via metabolic enhancers has been proposed as potential therapeutic strategy for Duchenne muscular dystrophy (DMD). Metformin, a widely-prescribed anti-hyperglycemic drug which activates AMPK via mitochondrial respiratory chain, has been recently tested in DMD patients in synergy with nitric oxide (NO)-precursors, with encouraging results. However, preclinical data supporting the use of metformin in DMD are still poor, and its actions on skeletal muscle appear controversial...
April 20, 2018: Biochemical Pharmacology
https://www.readbyqxmd.com/read/29668323/deficiency-of-selenoprotein-s-an-endoplasmic-reticulum-resident-oxidoreductase-impairs-the-contractile-function-of-fast-twitch-hindlimb-muscles
#4
Alex Bernard Addinsall, Craig Robert Wright, Christopher S Shaw, Natasha L McRae, Leonard George Forgan, Chia-Heng Weng, Xavier A Conlan, Paul S Francis, Zoe M Smith, Sofianos Andrikopoulos, Nicole Stupka
Selenoprotein S (Seps1) is an endoplasmic reticulum (ER) resident antioxidant implicated in ER stress and inflammation. In human vastus lateralis and mouse hindlimb muscles, Seps1 localization and expression was fiber type specific. In male Seps1+/- heterozygous mice, spontaneous physical activity was reduced compared to wild type littermates ( d=1.10, P=0.029). A similar trend also observed in Seps1-/- knockout mice ( d=1.12, P=0.051). Whole body metabolism, body composition, extensor digitorum longus (EDL) and soleus mass, and myofibre diameter were unaffected by genotype...
April 18, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/29464929/distinct-signal-transductions-in-fast-and-slow-twitch-muscles-upon-denervation
#5
Hongbo Gao, Yi-Fan Li
Denervation induces skeletal muscle atrophy, which primarily impairs oxidative slow twitch fibers. The underlying mechanism of this phenomenon, however, remains to be addressed. We hypothesize that denervation-induced fiber-specific atrophy may result from the distinct activities of different signaling pathways that are involved in protein synthesis and degradation in fast- and slow-twitch fibers. In this study, 1-month-old male mice were subjected to unilateral sciatic denervation for 4 days. Fast-twitch muscle extensor digitorum longus (EDL) and slow-twitch muscle soleus were collected from the denervated side and the control side of hind limbs...
February 2018: Physiological Reports
https://www.readbyqxmd.com/read/29315934/effect-of-eukarion-134-on-akt-mtor-signalling-in-the-rat-soleus-during-7-days-of-mechanical-unloading
#6
J Matthew Kuczmarski, Jeff M Hord, Yang Lee, Vinicius Guzzoni, Dinah Rodriguez, Matthew S Lawler, Erika L Garcia-Villatoro, Dylan Holly, Patrick Ryan, Kristian Falcon, Marcela Garcia, Mariana Janini Gomes, James D Fluckey, John M Lawler
NEW FINDINGS: What is the central question of this study? Translocation of nNOSμ initiates catabolic signalling via FoxO3a and skeletal muscle atrophy during mechanical unloading. Recent evidence suggests that unloading-induced muscle atrophy and FoxO3a activation are redox sensitive. Will a mimetic of superoxide dismutase and catalase (i.e. Eukarion-134) also mitigate suppression of the Akt-mTOR pathway? What is the main finding and its importance? Eukarion-134 rescued Akt-mTOR signalling and sarcolemmal nNOSμ, which were linked to protection against the unloading phenotype, muscle fibre atrophy and partial fibre-type shift from slow to fast twitch...
April 1, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29299218/electrical-stimulation-frequency-and-skeletal-muscle-characteristics-effects-on-force-and-fatigue
#7
Maria Vromans, Pouran Faghri
This investigation aimed to determine the force and muscle surface electromyography (EMG) responses to different frequencies of electrical stimulation (ES) in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions) during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB) and vastus lateralis (VL) when activated by ES at three frequencies (10, 35, and 50Hz). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation...
December 5, 2017: European Journal of Translational Myology
https://www.readbyqxmd.com/read/29291007/alteration-of-muscle-fiber-characteristics-and-the-ampk-sirt1-pgc-1%C3%AE-axis-in-skeletal-muscle-of-growing-pigs-fed-low-protein-diets-with-varying-branched-chain-amino-acid-ratios
#8
Yehui Duan, Fengna Li, Wenlong Wang, Qiuping Guo, Chaoyue Wen, Yulong Yin
There mainly exists four major myosin heavy chains (MyHC) (i.e., I, IIa, IIx, and IIb) in growing pigs. The current study aimed to explore the effects of low-protein diets supplemented with varying branched-chain amino acids (BCAAs) on muscle fiber characteristics and the AMPK-SIRT1-PGC-1α axis in skeletal muscles. Forty growing pigs (9.85 ± 0.35 kg) were allotted to 5 groups and fed with diets supplemented with varying leucine: isoleucine: valine ratios: 1:0.51:0.63 (20% crude protein, CP), 1:1:1 (17% CP), 1:0...
December 5, 2017: Oncotarget
https://www.readbyqxmd.com/read/29289708/effect-of-ageing-on-the-myosin-heavy-chain-composition-of-the-human-sternocleidomastoid-muscle
#9
M Meznaric, I Eržen, P Karen, E Cvetko
The myosin heavy chain (MyHC) composition of ageing limb muscles is transformed into a slower phenotype and expresses fast-twitch fibre type atrophy, presumably due to age-related motor unit remodelling and a change in the patterns of physical activity. It is not known if ageing affects the sternocleidomastoid muscle (SCM) in a similar way. The goal of the study was to analyze the MyHC composition and the size of muscle fibres in the ageing SCM by immunohistochemical methods and quantitative analysis and stereology using our own software for morphometry...
March 2018: Annals of Anatomy, Anatomischer Anzeiger: Official Organ of the Anatomische Gesellschaft
https://www.readbyqxmd.com/read/29169055/functional-electrical-stimulation-induced-muscular-fatigue-effect-of-fiber-composition-and-stimulation-frequency-on-rate-of-fatigue-development
#10
Maria Vromans, Pouran D Faghri
This investigation evaluated the progression towards fatigue in two muscles of differing fast- and slow-twitch fiber proportions (abductor pollicis brevis (APB) and vastus lateralis (VL)) when activated by functional electrical stimulation (FES) at three frequencies (10, 35, and 50 Hz). Fatigue was defined as a 50% drop from the initial FES-induced force of 25% maximal voluntary contraction (MVC). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation...
February 2018: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/28983629/expression-of-carbonic-anhydrase-iii-and-skeletal-muscle-remodeling-following-selective-denervation
#11
He Huang, Yanling Zhao, Xiliang Shang, Xueyuan Liu, Huimin Ren
Carbonic anhydrase III (CAIII) is expressed selectively in type I (slow‑twitch) myofibers. To investigate the association between changes in the expression of CAIII and skeletal muscle structure following denervation, the present study stained adjacent sections of skeletal muscle for ATPase and immunohistochemically for CAIII. In addition, differences in the protein expression and phosphatase activity of CAIII were examined by western blot and phosphatase staining between rat soleus and extensol digitorum longus (EDL) muscles, which are composed of predominantly slow‑ and fast‑twitch fibers, respectively...
December 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28977603/androgen-action-via-the-androgen-receptor-in-neurons-within-the-brain-positively-regulates-muscle-mass-in-male-mice
#12
Rachel A Davey, Michele V Clarke, Patricia K Russell, Kesha Rana, Jane Seto, Kelly N Roeszler, Jackie M Y How, Ling Yeong Chia, Kathryn North, Jeffrey D Zajac
Although it is well established that exogenous androgens have anabolic effects on skeletal muscle mass in humans and mice, data from muscle-specific androgen receptor (AR) knockout (ARKO) mice indicate that myocytic expression of the AR is dispensable for hind-limb muscle mass accrual in males. To identify possible indirect actions of androgens via the AR in neurons to regulate muscle, we generated neuron-ARKO mice in which the dominant DNA binding-dependent actions of the AR are deleted in neurons of the cortex, forebrain, hypothalamus, and olfactory bulb...
October 1, 2017: Endocrinology
https://www.readbyqxmd.com/read/28966053/proteome-analysis-in-dystrophic-mdx-mouse-muscle-reveals-a-drastic-alteration-of-key-metabolic-and-contractile-proteins-after-chronic-exercise-and-the-potential-modulation-by-anti-oxidant-compounds
#13
Tania Gamberi, Tania Fiaschi, Elisa Valocchia, Alessandra Modesti, Paola Mantuano, Jean-Francois Rolland, Francesca Sanarica, Annamaria De Luca, Francesca Magherini
Weakness and fatigability are typical features of Duchenne muscular dystrophy patients and are aggravated in dystrophic mdx mice by chronic treadmill exercise. In the present study, we describe, the pattern of differentially abundant spots that is associated to the worsening of dystrophy phenotype induced by chronic exercise. Our proteomic analysis pointed out 34 protein spots with different abundance between sedentary and exercised mdx mice. These proteins belong mostly to glucose metabolism, energy production and sarcomere structure categories...
January 6, 2018: Journal of Proteomics
https://www.readbyqxmd.com/read/28927901/age-related-reductions-in-muscle-quality-influence-the-relative-differences-in-strength-and-power
#14
Gena R Gerstner, Hayden K Giuliani, Jacob A Mota, Eric D Ryan
Age-related changes in the relative differences in isokinetic strength and power may reflect fast twitch fiber function. We aimed to examine the influence of muscle quality on the relative differences in strength and power in younger and older men. Twenty younger (20.1±1.5yrs) and 20 older (69.5±3.1yrs) healthy, recreationally active men performed two plantarflexion maximal voluntary isometric contractions (MVCs) and three maximal concentric isokinetic contractions at a slow (0.52rad·s(-1)) and fast (2.09rad·s(-1)) velocity...
December 1, 2017: Experimental Gerontology
https://www.readbyqxmd.com/read/28767362/modeling-of-stretch-reflex-activation-considering-muscle-type
#15
Moon J Kang, Choongsoo S Shin, Hong H Yoo
Although the stretch reflex plays an important role in spasticity, so far the stretch reflex has not been sufficiently investigated. Previous stretch reflex activation models have some limitations, whereby they are not able to predict outcomes of some stretch reflex cases and do not consider uneven distribution of muscle length and stretch velocity on reflex activation. The purpose of this study was 1) to develop a modified stretch reflex activation model employing a new muscle length threshold and weighting factors for slow-twitch fiber and fast-twitch fiber, and 2) to validate the model using pendulum experiments of the lower and upper limbs...
July 31, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28573481/copper-pyrithione-a-booster-biocide-induces-abnormal-muscle-and-notochord-architecture-in-zebrafish-embryogenesis
#16
Kelly M Almond, Louis D Trombetta
The metal pyrithiones, principally zinc (ZnPT) and copper (CuPT), are replacing tributyltin (TBT) as antifouling agents. Zebrafish embryos were exposed within the first hour after fertilization to 12 and 64 µg/L of CuPT for 24 h. Morphological abnormalities in notochord and muscle architecture were observed at 96 h post fertilization (hpf). TEM revealed abnormal electron dense deposits in the notochord sheath and muscle fiber degeneration in animals treated with 12 µg/L of CuPT. Embryos that were exposed to 64 µg/L of CuPT displayed severe muscle fiber degeneration including abnormal A and I band patterning and altered z disk arrangement...
September 2017: Ecotoxicology
https://www.readbyqxmd.com/read/28522764/obesity-induced-discrepancy-between-contractile-and-metabolic-phenotypes-in-slow-and-fast-twitch-skeletal-muscles-of-female-obese-zucker-rats
#17
Luz M Acevedo, Ana I Raya, Rafael Ríos, Escolástico Aguilera-Tejero, Jose-Luis L Rivero
A clear picture of skeletal muscle adaptations to obesity and related comorbidities remains elusive. This study describes fiber-type characteristics (size, proportions, and oxidative enzyme activity) in two typical hind limb muscles with opposite structure and function in an animal model of genetic obesity. Lesser fiber diameter, fiber type composition, and histochemical succinic dehydrogenase activity (an oxidative marker) of muscle fiber types were assessed in slow- (soleus) and fast-twitch (tibialis cranialis) muscles of obese Zucker rats, and compared with age- (16 weeks) and sex-matched (females) lean Zucker rats (N=16/group)...
May 18, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28480592/slow-myofiber-commitment-by-semaphorin-3a-secreted-from-myogenic-stem-cells
#18
Ryuichi Tatsumi, Takahiro Suzuki, Mai-Khoi Q Do, Yuki Ohya, Judy E Anderson, Ayumi Shibata, Mai Kawaguchi, Shunpei Ohya, Hideaki Ohtsubo, Wataru Mizunoya, Shoko Sawano, Yusuke Komiya, Riho Ichitsubo, Koichi Ojima, Shin-Ichiro Nishimatsu, Tsutomu Nohno, Yutaka Ohsawa, Yoshihide Sunada, Mako Nakamura, Mitsuhiro Furuse, Yoshihide Ikeuchi, Takanori Nishimura, Takeshi Yagi, Ronald E Allen
Recently, we found that resident myogenic stem satellite cells upregulate a multi-functional secreted protein, semaphorin 3A (Sema3A), exclusively at the early-differentiation phase in response to muscle injury; however, its physiological significance is still unknown. Here we show that Sema3A impacts slow-twitch fiber generation through a signaling pathway, cell-membrane receptor (neuropilin2-plexinA3) → myogenin-myocyte enhancer factor 2D → slow myosin heavy chain. This novel axis was found by small interfering RNA-transfection experiments in myoblast cultures, which also revealed an additional element that Sema3A-neuropilin1/plexinA1, A2 may enhance slow-fiber formation by activating signals that inhibit fast-myosin expression...
May 7, 2017: Stem Cells
https://www.readbyqxmd.com/read/28474872/is-the-stiffness-of-human-muscle-and-tendon-structures-related-to-muscle-fiber-composition-in-vivo
#19
Keitaro Kubo, Daisuke Miyazaki, Hideaki Yata, Shozo Shimoju, Masaji Okada, Naoya Tsunoda
AIM: The aim of the present study was to investigate the relationship between estimated muscle fiber composition (time-to-peak twitch torque; TPT) and muscle stiffness under passive and active conditions as well as stiffness of tendon structures in human plantar flexors. METHODS: TPT was assessed using supramaximal electrical stimulation. Active muscle stiffness in the medial gastrocnemius muscle was calculated based on changes in estimated muscle force and fascicle length during fast stretching after 50% maximal isometric contractions...
April 26, 2017: Journal of Sports Medicine and Physical Fitness
https://www.readbyqxmd.com/read/28161523/myomaker-is-required-for-the-fusion-of-fast-twitch-myocytes-in-the-zebrafish-embryo
#20
Weibin Zhang, Sudipto Roy
During skeletal muscle development, myocytes aggregate and fuse to form multinucleated muscle fibers. Inhibition of myocyte fusion is thought to significantly derail the differentiation of functional muscle fibers. Despite the purported importance of fusion in myogenesis, in vivo studies of this process in vertebrates are rather limited. Myomaker, a multipass transmembrane protein, has been shown to be the first muscle-specific fusion protein essential for myocyte fusion in the mouse. We have generated loss-of-function alleles in zebrafish myomaker, and found that fusion of myocytes into syncytial fast-twitch muscles was significantly compromised...
March 1, 2017: Developmental Biology
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