Special Issue "Muscle Structure and Function"
A special issue of Biology (ISSN 2079-7737).
Deadline for manuscript submissions: closed (15 May 2014)
Muscle is amazingly adaptable. Over a long time scale, a variety of muscle types have evolved to perform distinct and specialized functions based on a well conserved design of interdigitating myofilaments. Over a short time scale, muscle adapts to exercise and training by undergoing biochemical, metabolic, and structural remodeling. Muscle relies on different mechanisms to supply energy for contractile and homeostatic processes and increasing evidence suggests a variety of strategies by which energy production and transfer is regulated in different muscles and in muscles subjected to acute exercise and training. Cell biology research over the past decade has increasingly demonstrated a high degree of cytoplasmic compartmentalization defined not by structural boundaries, but by transient molecular interactions among pathway components and cellular structures. For this special issue, we welcome original research and review articles that examine muscle metabolism, in health and disease, in light of the emerging paradigm of the cytoplasm as an interconnected network of microdomains.
Prof. Dr. Jim O. Vigoreaux
Manuscript Submission Information
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- energy transfer
- aerobic pathways
The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.
Type of Paper: Review
Title: McArdle disease and exercise physiology
Authors: Yu Kitaoka
Affiliation: Department of Sports Sciences, The University of Tokyo, Japan; E-Mail: firstname.lastname@example.org
Abstract: McArdle disease (Glycogen storage disease Type V; MD) is a metabolic myopathy caused by a deficiency in muscle glycogen phosphorylase. Since muscle glycogen is an important fuel for muscle during exercise, this inborn error of metabolism provides a model to understand the importance of muscle glycogen and compensatory adaptations to a defective metabolic pathway. Patients with MD have exercise intolerance with symptoms including premature fatigue, myalgia, and/or muscle cramps. However, it is also known that MD patients can continue to exercise as a result of the “second wind” phenomenon, due to the improved delivery of blood-borne fuels to the working muscle. The present review covers what this disease can teach us about exercise physiology, and particularly focuses on the compensatory pathways of energy-delivering mechanisms in the absence of glycogenolysis.
Type of Paper: Article
Title: High Intensity Training Improves Health and Physical Function in Untrained Middle Aged Adults
Authors: Simon Adamson 1, Ross Lorimer 1, James Cobley 1, Ray Lloyd 2, John Babraj 1
Affiliation: 1. Division of Sport and Exercise Science, Abertay University, Dundee, Scotland, DD1 1HG; E-Mail: J.Babraj@abertay.ac.uk
2. Leeds Trinity University, Leeds, LS18 5HD, UK
Abstract: High intensity training (HIT) is effective at improving health; however, it is unknown whether HIT also improves physical function. This study aimed to determine whether HIT improves metabolic health and physical function in untrained middle aged individuals. Fourteen (three male and eleven female) untrained individuals were recruited (control group n=6: age 42 ± 8 y, weight 64 ± 10 kg, BMI 24 ± 2 kg.m-2 or HIT group n=8: age 43 ± 8 y, weight 80 ± 8 kg, BMI 29 ± 5 kg.m-2). Training was performed twice weekly, consisting of 10 x 6-second sprints with a 1 minute recovery between each sprint. Metabolic health (oral glucose tolerance test), aerobic capacity (incremental time to exhaustion on a cycle ergometer) and physical function (get up and go test, sit to stand test and loaded 50m walk) were determined before and after training. Following 8 weeks of HIT there was a significant improvement in aerobic capacity (8% increase in VO2 peak; p<0.001), physical function (11% - 27% respectively; p < 0.05) and a reduction in blood glucose area under the curve (6% reduction; p < 0.05). This study demonstrates for the first time the potential of HIT as a training intervention to improve physical function as we age.
Type of Paper: Review
Title: Discerning primary and secondary factors responsible for muscle fatigue in multisystem diseases
Authors: Michael J. Toth and David W. Maughan *
Affiliation: Departments of Medicine and Molecular Physiology & Biophysics, University of Vermont, Burlington, VT, USA; E-mail: email@example.com
Abstract: Muscular fatigue at rest or upon exertion is a common symptom of numerous acute and chronic diseases, including heart failure, chronic obstructive pulmonary disease, cancer, myalgic encephalomyelitis/chronic fatigue syndrome, multiple sclerosis, and many others. In these multi-system diseases, the physiological determinants of enhanced muscle fatigue likely reflect some combination of metabolic, neurological, and myofibrillar adaptations. Although much attention has focused on adaptations specific to skeletal muscle and their role in fatigue, most studies have neglected the role of physical inactivity, which, through muscle deconditioning, likely contributes to the symptomatic fatigue that accompanies the disease/syndrome. In this commentary, we briefly review the muscle phenotype in these conditions in the context of whether they relate to the primary disease or whether they arise secondary to disease-related reductions in physical activity. Knowledge of the etiology of the skeletal muscle adaptations in these conditions, and their contribution to fatigue symptoms, is important for understanding the utility of exercise rehabilitation as an intervention to mitigate the physiological precipitants of fatigue.
Type of Paper: Article
Title: Circadian Specific Hypertrophic Potential: In Vivo Insulin-like Growth Factor-Binding Protein-3, cortisol, metabolic, and in vitro cellular differentiation evidence
Authors: Simon D Burley 1,2, Jayde Whittingham-Dowd 3,4, Jeremy Allen 4, Jean-Francois Grosset 2,5 and Gladys L Onambélé-Pearson 2
Affiliations: 1 Centre of Human applied Physiology, School of Health Sciences, University of Wollongong, Wollongong, Australia
2 Exercise & Sport Science, Manchester Metropolitan University, Crewe Green Road, Crewe, CW1 5DU, UK; E-Mail: firstname.lastname@example.org
3 Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester, Manchester M23 9LT
4 School of Health, Sport & Rehabilitation Sciences, University of Salford, Salford, Greater Manchester M5 4WT, UK
5 CNRS UMR 7338, Biomécanique et Bioingénierie, Université de Technologie de Compiègne, 60205 Compiègne cedex, France
Abstract: Identifying the optimal environment for musculoskeletal hypertrophy is central to training and rehabilitation. Therefore, we aimed to determine any in vivo morning-to-evening difference in the acute insulin-like growth factor-binding protein-3 (IGFBP-3) and cortisol responses to resistance exercise. We used in vitro cellular differentiations to substantiate any in vivo findings. Twenty-four male participants completed resistance exercise at 70% 1RM, in morning (0800hrs) and evening (1800hrs) sessions. A representative sub-sample of 16 of these males returned later for control (no training) protocols. Collected sera were analysed for IGFBP-3 and cortisol concentrations using enzyme-linked immunosorbant assay, as well as C2C12 cells incubation during differentiation. Our data strongly indicate that IGFBP-3 (linked to increased myoblast differentiation/muscle metabolism) and cortisol (linked to skeletal muscle breakdown) circadian fluctuations, may be used in sport/clinical rehabilitation, to maximise the potential for muscle hypertrophy.
Type of Paper: Review
Title: The intriguing dual lattices of the myosin filaments in vertebrate striated muscles: evolution and advantage.
Authors: Pradeep K. Luther 1 and John M. Squire 2
1 Molecular Medicine Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ; E-Mail: email@example.com
2 Muscle Contraction Group, School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD; E-Mail: firstname.lastname@example.org
Abstract: Myosin filaments in vertebrate striated muscle have a long roughly cylindrical backbone with cross-bridge projections on the surfaces of both halves except for a short central bare zone. In the middle of this central region the filaments are cross-linked by the M-band which holds them in a well-defined hexagonal lattice in the muscle A-band. During muscular contraction the M-band-defined orientation of the myosin filaments around their long axes influences the interactions that the cross-bridges can make with the neighbouring actin filaments. We can visualise this filament orientation by electron microscopy of thin cross-sections in the bare-region immediately adjacent to the M-band where the filament profiles are distinctly triangular. In the muscles of teleost fishes, the thick filament triangular profiles have a single orientation giving what we call the simple lattice. In other vertebrates, for example all the tetrapods, the thick filaments have one of two orientations where the triangles point in opposite directions (they are rotated by 60° or 180°) according to set rules. Such a distribution cannot be developed in an ordered fashion across a large 2D lattice, but there are small domains of superlattice such that the next-nearest neighbouring thick filaments have the same orientation. We believe that this difference in the lattice forms can lead to different contractile behaviours. We review here the emergence of the simple and superlattice forms by examining the muscles of several species ranging back to primitive vertebrates and we discuss the functional differences that the two lattice forms may have.
Type of Paper: Article
Title: Transcriptomic and proteomic responses of skeletal muscle in lipolisaccharide-treated rainbow trout (Oncorhynchus mykiss)
Authors: Leonardo J. Magnoni 1, Nerea Roher 2 and Josep V. Planas 1,*
1Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona and Institut de Biomedicina de la Universitat de Barcelona (IBUB), 08028 Barcelona, Spain; E-Mail: E-Mail: email@example.com
2Institut de Biotecnologia i de Biomedicina-Parc de Recerca UAB, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Abstract: The physiological consequences of the activation of the immune system in skeletal muscle are not completely understood. In order to investigate the effects of the activation of the immune system by bacterial pathogens on skeletal muscle function, we administered lipopolysaccharide (LPS), an active component of the cell wall of Gram negative bacteria, into rainbow trout, a non-mammalian vertebrate, and performed transcriptomic and proteomic analyses in skeletal muscle. We examined changes in gene expression in fast and slow skeletal muscle in rainbow trout at 24 and 72 h after LPS treatment (8 mg/kg) by microarray analysis. At the transcriptional level, we observed important changes in metabolic, mitochondrial and structural genes in fast and slow skeletal muscle. In slow skeletal muscle, LPS caused marked changes in the expression of genes related to oxidative phosphorylation, while in fast skeletal muscle LPS administration caused major changes in the expression of genes coding for glycolytic enzymes. Moreover, we observed a differential transcriptional response of the two types of skeletal muscle examined that appears to be related with their contractile characteristics and immune competences. We also evaluated the effects of LPS administration on the proteomic expression pattern in fast skeletal muscle and identified 14 protein spots that were differentially induced in LPS-treated trout, primarily corresponding to glycolytic enzymes. Our results evidence a robust and tissue-specific response of skeletal muscle to an acute inflammatory challenge, affecting energy utilization and possibly growth, in rainbow trout.