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slow and fast twitch muscle fibers and activity

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
Lee D Roberts, Tom Ashmore, Ben D McNally, Steven A Murfitt, Bernadette O Fernandez, Martin Feelisch, Ross Lindsay, Mario Siervo, Elizabeth A Williams, Andrew J Murray, Julian L Griffin
Exercise is an effective intervention for prevention and treatment of type 2 diabetes. Skeletal muscle combines multiple signals contributing to the beneficial effects of exercise on cardiometabolic health. Inorganic nitrate increases exercise efficiency, tolerance and performance. The transcriptional regulator peroxisome proliferator-activated receptorγ coactivator1α (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...
December 27, 2016: Diabetes
Kelly Stratton, Pouran D Faghri
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...
June 13, 2016: European Journal of Translational Myology
T L Dutka, J P Mollica, C R Lamboley, V C Weerakkody, D W Greening, G S Posterino, R M Murphy, G D Lamb
Nitric oxide is generated in skeletal muscle with activity and decreases Ca(2+)-sensitivity of the contractile apparatus, putatively by S-nitrosylation of an unidentified protein. We investigate the mechanistic basis of this effect and its relationship to the oxidation-induced increase in Ca(2+)-sensitivity in mammalian fast-twitch (FT) fibers mediated by S-glutathionylation of Cys134 on fast troponin I (TnIf). Force-[Ca(2+)] characteristics of the contractile apparatus in mechanically-skinned fibers were assessed by direct activation with heavily Ca(2+)-buffered solutions...
December 14, 2016: American Journal of Physiology. Cell Physiology
Leonardo Nogara, Nariman Naber, Edward Pate, Marcella Canton, Carlo Reggiani, Roger Cooke
We identify a target for treating obesity and type 2 diabetes, the consumption of calories by an increase in the metabolic rate of resting skeletal muscle. The metabolic rate of skeletal muscle can be increased by shifting myosin heads from the super-relaxed state (SRX), with a low ATPase activity, to a disordered relaxed state (DRX), with a higher ATPase activity. The shift of myosin heads was detected by a change in fluorescent intensity of a probe attached to the myosin regulatory light chain in skinned skeletal fibers, allowing us to perform a high-throughput screen of 2,128 compounds...
November 15, 2016: Proceedings of the National Academy of Sciences of the United States of America
Alba Chacon-Cabrera, Helena Lund-Palau, Joaquim Gea, Esther Barreiro
BACKGROUND: Disuse muscle atrophy is a major comorbidity in patients with chronic diseases including cancer. We sought to explore the kinetics of molecular mechanisms shown to be involved in muscle mass loss throughout time in a mouse model of disuse muscle atrophy and recovery following immobilization. METHODS: Body and muscle weights, grip strength, muscle phenotype (fiber type composition and morphometry and muscle structural alterations), proteolysis, contractile proteins, systemic troponin I, and mitochondrial content were assessed in gastrocnemius of mice exposed to periods (1, 2, 3, 7, 15 and 30 days) of non-invasive hindlimb immobilization (plastic splint, I cohorts) and in those exposed to reloading for different time-points (1, 3, 7, 15, and 30 days, R cohorts) following a seven-day period of immobilization...
2016: PloS One
Yoo Kim, Daeyoung Kim, Yeonhwa Park
Previously, it was reported that conjugated linoleic acid (CLA) with exercise training potentially improved endurance capacity via the peroxisome proliferator-activated receptor δ (PPARδ)-mediated mechanism in mice. This study determined the role of exercise and/or CLA in endurance capacity and PPARδ-associated regulators. Male 129Sv/J mice were fed either control (soybean oil) or CLA (0.5%) containing diets for 4 weeks and were further divided into sedentary or training regimes. CLA supplementation significantly reduced body weight and fat mass independent of exercise during the experimental period...
September 7, 2016: Journal of Nutritional Biochemistry
Anna Salazar-Degracia, David Blanco, Mònica Vilà-Ubach, Gabriel de Biurrun, Carlos Ortiz de Solórzano, Luis M Montuenga, Esther Barreiro
BACKGROUND: Muscle wasting negatively impacts the progress of chronic diseases such as lung cancer (LC) and emphysema, which are in turn interrelated. OBJECTIVES: We hypothesized that muscle atrophy and body weight loss may develop in an experimental mouse model of lung carcinogenesis, that the profile of alterations in muscle fiber phenotype (fiber type composition and morphometry, muscle structural alterations, and nuclear apoptosis), and in muscle metabolism are similar in both respiratory and limb muscles of the tumor-bearing mice, and that the presence of underlying emphysema may influence those events...
2016: Journal of Translational Medicine
Xuan Liu, Nares Trakooljul, Frieder Hadlich, Eduard Muráni, Klaus Wimmers, Siriluck Ponsuksili
BACKGROUND: MicroRNAs (miRNAs) are small non-coding RNAs that play critical roles in diverse biological processes via regulation of gene expression including in skeletal muscles. In the current study, miRNA expression profile was investigated in longissimus muscle biopsies of malignant hyperthermia syndrome-negative Duroc and Pietrain pigs with distinct muscle metabolic properties in order to explore the regulatory role of miRNAs related to mitochondrial respiratory activity and metabolic enzyme activity in skeletal muscle...
2016: BMC Genomics
Andrew J Murton, Matthew Maddocks, Francis B Stephens, Kanagaraj Marimuthu, Ruth England, Andrew Wilcock
INTRODUCTION: The loss of muscle is common in patients with advanced non-small-cell lung cancer (NSCLC) and contributes to the high morbidity and mortality of this group. The exact mechanisms behind the muscle loss are unclear. PATIENTS AND METHODS: To investigate this, 4 patients with stage IV NSCLC who met the clinical definitions for sarcopenia and cachexia were recruited, along with 4 age-matched healthy volunteers. After an overnight fast, biopsy specimens were obtained from the vastus lateralis, and the key components associated with inflammation and the control of muscle protein, carbohydrate, and fat metabolism were assessed...
June 25, 2016: Clinical Lung Cancer
Malgorzata Zimowska, Paulina Kasprzycka, Katarzyna Bocian, Kamila Delaney, Piotr Jung, Kinga Kuchcinska, Karolina Kaczmarska, Daria Gladysz, Wladyslawa Streminska, Maria Anna Ciemerych
INTRODUCTION: Skeletal muscles are characterized by their unique ability to regenerate. Injury of a so-called fast-twitch muscle, extensor digitorum longus (EDL), results in efficient regeneration and reconstruction of the functional tissue. In contrast, slow-twitch muscle (soleus) fails to properly reconstruct and develops fibrosis. This study focuses on soleus and EDL muscle regeneration and associated inflammation. METHODS: We determined differences in the activity of neutrophils and M1 and M2 macrophages using flow cytometry and differences in the levels of proinflammatory cytokines using Western blotting and immunolocalization at different times after muscle injury...
March 2017: Muscle & Nerve
M López-Alonso, M Miranda, J L Benedito, V Pereira, M García-Vaquero
The aim of this study was to evaluate essential and toxic element concentration of ten commercially available veal cuts, together with diaphragm, cardiac muscle and liver tissue from 10 animals of "Galician Supreme Veal". Essential trace elements (Co, Cr, Cu, Fe, Mn, Mo, Ni, Se and Zn) and toxic elements (As, Cd, Hg and Pb) were determined by ICP-MS. Essential trace element concentrations ranged from 0.002-55.64mg/kg between muscles. Toxic element concentrations were very low, and high numbers of samples showed unquantifiable residues of Cd and Pb...
November 2016: Meat Science
Domenico Tricarico, Maria Selvaggi, Giuseppe Passantino, Pasquale De Palo, Cataldo Dario, Pasquale Centoducati, Alessandra Tateo, Angela Curci, Fatima Maqoud, Antonietta Mele, Giulia M Camerino, Antonella Liantonio, Paola Imbrici, Nicola Zizzo
The ATP-sensitive K(+)-channels (KATP) are distributed in the tissues coupling metabolism with K(+) ions efflux. KATP subunits are encoded by KCNJ8 (Kir6.1), KCNJ11 (Kir6.2), ABCC8 (SUR1), and ABCC9 (SUR2) genes, alternative RNA splicing give rise to SUR variants that confer distinct physiological properties on the channel. An high expression/activity of the sarco-KATP channel is observed in various rat fast-twitch muscles, characterized by elevated muscle strength, while a low expression/activity is observed in the slow-twitch muscles characterized by reduced strength and frailty...
2016: Frontiers in Physiology
Jared Talbot, Lisa Maves
Skeletal muscle fibers are classified into fiber types, in particular, slow twitch versus fast twitch. Muscle fiber types are generally defined by the particular myosin heavy chain isoforms that they express, but many other components contribute to a fiber's physiological characteristics. Skeletal muscle fiber type can have a profound impact on muscle diseases, including certain muscular dystrophies and sarcopenia, the aging-induced loss of muscle mass and strength. These findings suggest that some muscle diseases may be treated by shifting fiber type characteristics either from slow to fast, or fast to slow phenotypes, depending on the disease...
July 2016: Wiley Interdisciplinary Reviews. Developmental Biology
Emmy Manders, Peter I Bonta, Jaap J Kloek, Petr Symersky, Harm-Jan Bogaard, Pleuni E Hooijman, Jeff R Jasper, Fady I Malik, Ger J M Stienen, Anton Vonk-Noordegraaf, Frances S de Man, Coen A C Ottenheijm
Patients with pulmonary hypertension (PH) suffer from inspiratory muscle weakness. However, the pathophysiology of inspiratory muscle dysfunction in PH is unknown. We hypothesized that weakness of the diaphragm, the main inspiratory muscle, is an important contributor to inspiratory muscle dysfunction in PH patients. Our objective was to combine ex vivo diaphragm muscle fiber contractility measurements with measures of in vivo inspiratory muscle function in chronic thromboembolic pulmonary hypertension (CTEPH) patients...
July 1, 2016: American Journal of Physiology. Lung Cellular and Molecular Physiology
Teet Seene, Priit Kaasik
Muscle weakness in corticosteroid myopathy is mainly the result of the destruction and atrophy of the myofibrillar compartment of fast-twitch muscle fibers. Decrease of titin and myosin, and the ratio of nebulin and MyHC in myopathic muscle, shows that these changes of contractile and elastic proteins are the result of increased catabolism of the abovementioned proteins in skeletal muscle. Slow regeneration of skeletal muscle is in good correlation with a decreased number of satellite cells under the basal lamina of muscle fibers...
2016: Metabolites
Alexander V Ovechkin, Dimitry G Sayenko, Elena N Ovechkina, Sevda C Aslan, Teresa Pitts, Rodney J Folz
The objective of this study was to examine the feasibility of a full-scale investigation of the neurophysiological mechanisms of COPD-induced respiratory neuromuscular control deficits. Characterization of respiratory single- and multi-muscle activation patterns using surface electromyography (sEMG) were assessed along with functional measures at baseline and following 21±2 (mean±SD) sessions of respiratory motor training (RMT) performed during a one-month period in four patients with GOLD stage II or III COPD...
July 15, 2016: Respiratory Physiology & Neurobiology
Rebeca Corpeno Kalamgi, Heba Salah, Stefano Gastaldello, Vicente Martinez-Redondo, Jorge L Ruas, Wen Fury, Yu Bai, Jesper Gromada, Roberta Sartori, Denis C Guttridge, Marco Sandri, Lars Larsson
KEY POINTS: Using an experimental rat intensive care unit (ICU) model, not limited by early mortality, we have previously shown that passive mechanical loading attenuates the loss of muscle mass and force-generation capacity associated with the ICU intervention. Mitochondrial dynamics have recently been shown to play a more important role in muscle atrophy than previously recognized. In this study we demonstrate that mitochondrial dynamics, as well as mitophagy, is affected by mechanosensing at the transcriptional level, and muscle changes induced by unloading are counteracted by passive mechanical loading...
August 1, 2016: Journal of Physiology
E Blotnick, L Anglister
Acetylcholinesterase plays a major role in neuromuscular transmission and is regulated by neuromuscular activity. Since fast-twitch motor units are recruited with increased motor demand, we examined acetylcholinesterase regulation in rat leg muscles following treadmill training. Total acetylcholinesterase and specifically the membrane-bound tetramer increased in exercised fast-, but not slow-twitch muscles, while other isoforms remained unchanged. Synaptic acetylcholinesterase increased markedly in neuromuscular junctions of trained fibers, without concomitant changes in synaptic acetylcholine receptor, thus elevating synaptic acetylcholinesterase/receptor ratios...
April 5, 2016: Neuroscience
Shirin Pourteymour, Sindre Lee, Torgrim M Langleite, Kristin Eckardt, Marit Hjorth, Christian Bindesbøll, Knut T Dalen, Kåre I Birkeland, Christian A Drevon, Torgeir Holen, Frode Norheim
Perilipins (PLINs) coat the surface of lipid droplets and are important for the regulation of lipid turnover. Knowledge about the physiological role of the individual PLINs in skeletal muscle is limited although lipid metabolism is very important for muscle contraction. To determine the effect of long-term exercise on PLINs expression, 26 middle-aged, sedentary men underwent 12 weeks combined endurance and strength training intervention. Muscle biopsies from m. vastus lateralis and subcutaneous adipose tissue were taken before and after the intervention and total gene expression was measured with deep mRNA sequencing...
August 2015: Physiological Reports
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