151
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Ohlendieck K. Proteomics of skeletal muscle glycolysis. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:2089-101. [DOI: 10.1016/j.bbapap.2010.08.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 08/01/2010] [Accepted: 08/05/2010] [Indexed: 10/19/2022]
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152
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Gandra PG, Valente RH, Perales J, Pacheco AG, Macedo DV. Proteomic analysis of rat skeletal muscle submitted to one bout of incremental exercise. Scand J Med Sci Sports 2010; 22:207-16. [DOI: 10.1111/j.1600-0838.2010.01235.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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153
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Green HJ, Batada A, Cole B, Burnett ME, Kollias H, McKay S, Roy B, Schertzer J, Smith I, Tupling S. Cellular responses in skeletal muscle to a season of ice hockey. Appl Physiol Nutr Metab 2010; 35:657-70. [PMID: 20962922 DOI: 10.1139/h10-060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We hypothesized that a season of ice hockey would result in extensive remodeling of muscle. Tissue sampled from the vastus lateralis of 15 players (age = 20.6 ± 0.4 years; mean ± SE) prior to (PRE) and following (POST) a season was used to characterize specific adaptations. Measurement of representative metabolic pathway enzymes indicated higher maximal activities in POST than in PRE (p < 0.05) for succinic dehydrogenase (3.26 ± 0.31 vs. 3.91 ± 0.11 mol mg protein(-1) min(-1)), citrate synthase (7.26 ± 0.70 vs. 8.70 ± 0.55 mol mg protein(-1) min(-1)), and phosphofructokinase (12.8 ± 1.3 vs. 14.4 ± 0.96 mol mg protein(-1) min(-1)) only. The season resulted in an increase in Na+-K+-ATPase concentration (253 ± 6.3 vs. 265 ± 6.0 pmol g(-1) wet weight), a decrease (p < 0.05) in maximal activity of the sarcoplasmic reticulum Ca2+-ATPase (107 ± 4.2 micromol g protein(-1) min(-1) vs. 92.0 ± 4.6 micromol g protein(-1) min(-1)), and no change in the distribution (%) of fibre types. A smaller (p < 0.05) cross-sectional area (CSA) for both type I (-11.7%) and type IIA (-18.2%) fibres and a higher (p < 0.05) capillary count/CSA for type I (+17.9%) and type IIA (+17.2%) were also found over the season. No changes were found in peak oxygen consumption (51.4 ± 1.2 mL kg(-1) min(-1) vs. 52.3 ± 1.3 mL kg(-1) min(-1)). The results suggest, based on the alterations in oxidative and perfusion potentials and muscle mass, that the dominant adaptations are in support of oxidative metabolism, which occurs at the expense of fibre CSA and possibly force-generating potential.
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Affiliation(s)
- Howard J Green
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
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154
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Zusman M. There’s something about passive movement…. Med Hypotheses 2010; 75:106-10. [DOI: 10.1016/j.mehy.2010.01.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 01/31/2010] [Indexed: 12/20/2022]
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155
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Burch N, Arnold AS, Item F, Summermatter S, Brochmann Santana Santos G, Christe M, Boutellier U, Toigo M, Handschin C. Electric pulse stimulation of cultured murine muscle cells reproduces gene expression changes of trained mouse muscle. PLoS One 2010; 5:e10970. [PMID: 20532042 PMCID: PMC2881042 DOI: 10.1371/journal.pone.0010970] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 05/13/2010] [Indexed: 12/20/2022] Open
Abstract
Adequate levels of physical activity are at the center of a healthy lifestyle. However, the molecular mechanisms that mediate the beneficial effects of exercise remain enigmatic. This gap in knowledge is caused by the lack of an amenable experimental model system. Therefore, we optimized electric pulse stimulation of muscle cells to closely recapitulate the plastic changes in gene expression observed in a trained skeletal muscle. The exact experimental conditions were established using the peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC-1alpha) as a marker for an endurance-trained muscle fiber. We subsequently compared the changes in the relative expression of metabolic and myofibrillar genes in the muscle cell system with those observed in mouse muscle in vivo following either an acute or repeated bouts of treadmill exercise. Importantly, in electrically stimulated C2C12 mouse muscle cells, the qualitative transcriptional adaptations were almost identical to those in trained muscle, but differ from the acute effects of exercise on muscle gene expression. In addition, significant alterations in the expression of myofibrillar proteins indicate that this stimulation could be used to modulate the fiber-type of muscle cells in culture. Our data thus describe an experimental cell culture model for the study of at least some of the transcriptional aspects of skeletal muscle adaptation to physical activity. This system will be useful for the study of the molecular mechanisms that regulate exercise adaptation in muscle.
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Affiliation(s)
- Nathalie Burch
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Zurich, Switzerland
| | - Anne-Sophie Arnold
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Biozentrum, Department of Pharmacology/Neurobiology, University of Basel, Basel, Switzerland
| | - Flurin Item
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Zurich, Switzerland
| | - Serge Summermatter
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Biozentrum, Department of Pharmacology/Neurobiology, University of Basel, Basel, Switzerland
| | | | - Martine Christe
- Biozentrum, Department of Pharmacology/Neurobiology, University of Basel, Basel, Switzerland
| | - Urs Boutellier
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Zurich, Switzerland
| | - Marco Toigo
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Zurich, Switzerland
| | - Christoph Handschin
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Biozentrum, Department of Pharmacology/Neurobiology, University of Basel, Basel, Switzerland
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156
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Moreno-Sánchez N, Rueda J, Carabaño MJ, Reverter A, McWilliam S, González C, Díaz C. Skeletal muscle specific genes networks in cattle. Funct Integr Genomics 2010; 10:609-18. [PMID: 20524025 PMCID: PMC2990504 DOI: 10.1007/s10142-010-0175-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 04/21/2010] [Accepted: 04/30/2010] [Indexed: 11/29/2022]
Abstract
While physiological differences across skeletal muscles have been described, the differential gene expression underlying them and the discovery of how they interact to perform specific biological processes are largely to be elucidated. The purpose of the present study was, firstly, to profile by cDNA microarrays the differential gene expression between two skeletal muscle types, Psoas major (PM) and Flexor digitorum (FD), in beef cattle and then to interpret the results in the context of a bovine gene coexpression network, detecting possible changes in connectivity across the skeletal muscle system. Eighty four genes were differentially expressed (DE) between muscles. Approximately 54% encoded metabolic enzymes and structural-contractile proteins. DE genes were involved in similar processes and functions, but the proportion of genes in each category varied within each muscle. A correlation matrix was obtained for 61 out of the 84 DE genes from a gene coexpression network. Different groups of coexpression were observed, the largest one having 28 metabolic and contractile genes, up-regulated in PM, and mainly encoding fast-glycolytic fibre structural components and glycolytic enzymes. In FD, genes related to cell support seemed to constitute its identity feature and did not positively correlate to the rest of DE genes in FD. Moreover, changes in connectivity for some DE genes were observed in the different gene ontologies. Our results confirm the existence of a muscle dependent transcription and coexpression pattern and suggest the necessity of integrating different muscle types to perform comprehensive networks for the transcriptional landscape of bovine skeletal muscle.
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Affiliation(s)
- Natalia Moreno-Sánchez
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Ctra de A Coruña km 7.5, 28040 Madrid, Spain.
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157
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Schmutz S, Däpp C, Wittwer M, Durieux AC, Mueller M, Weinstein F, Vogt M, Hoppeler H, Flück M. A hypoxia complement differentiates the muscle response to endurance exercise. Exp Physiol 2010; 95:723-35. [DOI: 10.1113/expphysiol.2009.051029] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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158
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Abstract
Endurance athletes demonstrate an exceptional resistance to fatigue when exercising at high intensity. Much research has been devoted to the contribution of aerobic capacity for the economy of endurance performance. Important aspects of the fine-tuning of metabolic processes and power output in the endurance athlete have been overlooked. This review addresses how training paradigms exploit bioenergetic pathways in recruited muscle groups to promote the endurance phenotype. A special focus is laid on the genome-mediated mechanisms that underlie the conditioning of fatigue resistance and aerobic performance by training macrocycles and complements. The available data on work-induced muscle plasticity implies that different biologic strategies are exploited in athletic and untrained populations to boost endurance capacity. Olympic champions are probably endowed with a unique constitution that renders the conditioning of endurance capacity for competition particularly efficient.
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Affiliation(s)
- Martin Flueck
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK.
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159
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Flueck M. Myocellular limitations of human performance and their modification through genome-dependent responses at altitude. Exp Physiol 2010; 95:451-62. [DOI: 10.1113/expphysiol.2009.047605] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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160
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Prewitt JS, Freistroffer DV, Schreer JF, Hammill MO, Burns JM. Postnatal development of muscle biochemistry in nursing harbor seal (Phoca vitulina) pups: limitations to diving behavior? J Comp Physiol B 2010; 180:757-66. [PMID: 20140678 DOI: 10.1007/s00360-010-0448-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 01/12/2010] [Accepted: 01/15/2010] [Indexed: 10/19/2022]
Abstract
Adult marine mammal muscles rely upon a suite of adaptations for sustained aerobic metabolism in the absence of freely available oxygen (O(2)). Although the importance of these adaptations for supporting aerobic diving patterns of adults is well understood, little is known about postnatal muscle development in young marine mammals. However, the typical pattern of vertebrate muscle development, and reduced tissue O(2) stores and diving ability of young marine mammals suggest that the physiological properties of harbor seal (Phoca vitulina) pup muscle will differ from those of adults. We examined myoglobin (Mb) concentration, and the activities of citrate synthase (CS), beta-hydroxyacyl coA dehydrogenase (HOAD), and lactate dehydrogenase (LDH) in muscle biopsies from harbor seal pups throughout the nursing period, and compared these biochemical parameters to those of adults. Pups had reduced O(2) carrying capacity ([Mb] 28-41% lower than adults) and reduced metabolically scaled catabolic enzyme activities (LDH/RMR 20-58% and CS/RMR 29-89% lower than adults), indicating that harbor seal pup muscles are biochemically immature at birth and weaning. This suggests that pup muscles do not have the ability to support either the aerobic or anaerobic performance of adult seals. This immaturity may contribute to the lower diving capacity and behavior in younger pups. In addition, the trends in myoglobin concentration and enzyme activity seen in this study appear to be developmental and/or exercise-driven responses that together work to produce the hypoxic endurance phenotype seen in adults, rather than allometric effects due to body size.
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Affiliation(s)
- J S Prewitt
- Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Dr, Anchorage, AK 99508, USA.
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161
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Remels AHV, Langen RCJ, Schrauwen P, Schaart G, Schols AMWJ, Gosker HR. Regulation of mitochondrial biogenesis during myogenesis. Mol Cell Endocrinol 2010; 315:113-20. [PMID: 19804813 DOI: 10.1016/j.mce.2009.09.029] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 09/27/2009] [Accepted: 09/28/2009] [Indexed: 11/26/2022]
Abstract
Pathways involved in mitochondrial biogenesis associated with myogenic differentiation are poorly defined. Therefore, C(2)C(12) myoblasts were differentiated into multi-nucleated myotubes and parameters/regulators of mitochondrial biogenesis were investigated. Mitochondrial respiration, citrate synthase- and beta-hydroxyacyl-CoA dehydrogenase activity as well as protein content of complexes I, II, III and V of the mitochondrial respiratory chain increased 4-8-fold during differentiation. Additionally, an increase in the ratio of myosin heavy chain (MyHC) slow vs MyHC fast protein content was observed. PPAR transcriptional activity and transcript levels of PPAR-alpha, the PPAR co-activator PGC-1alpha, mitochondrial transcription factor A and nuclear respiratory factor 1 increased during differentiation while expression levels of PPAR-gamma decreased. In conclusion, expression and activity levels of genes known for their regulatory role in skeletal muscle oxidative capabilities parallel the increase in oxidative parameters during the myogenic program. In particular, PGC-1alpha and PPAR-alpha may be involved in the regulation of mitochondrial biogenesis during myogenesis.
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Affiliation(s)
- A H V Remels
- Department of Respiratory Medicine, Maastricht University Medical Centre+, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands.
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162
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Allen DL, Uyenishi JJ, Cleary AS, Mehan RS, Lindsay SF, Reed JM. Calcineurin activates interleukin-6 transcription in mouse skeletal muscle in vivo and in C2C12 myotubes in vitro. Am J Physiol Regul Integr Comp Physiol 2010; 298:R198-210. [PMID: 19907005 PMCID: PMC2806210 DOI: 10.1152/ajpregu.00325.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Accepted: 11/09/2009] [Indexed: 01/21/2023]
Abstract
Expression of the cytokine interleukin-6 (IL-6) by skeletal muscle is hugely increased in response to a single bout of endurance exercise, and this appears to be mediated by increases in intracellular calcium. We examined the effects of endurance exercise on IL-6 mRNA levels and promoter activity in skeletal muscle in vivo, and the role of the calcium-activated calcineurin signaling pathway on muscle IL-6 expression in vivo and in vitro. IL-6 mRNA levels in the mouse tibialis anterior (TA) were increased 2-10-fold by a single bout of treadmill exercise or by 3 days of voluntary wheel running. Moreover, an IL-6 promoter-driven luciferase transgene was activated in TA by both treadmill and wheel-running exercise and by injection with a calcineurin plasmid. Exercise also increased muscle mRNA expression of the calcineurin regulatory gene MCIP1, as did treatment of C(2)C(12) myotubes with the calcium ionophore A23187. Cotransfection of C(2)C(12) myotubes with a constitutively active calcineurin construct significantly increased while cotransfection with the calcineurin inhibitor CAIN inhibited activity of a mouse IL-6 promoter-reporter construct. Cotransfection with a myocyte enhancer-factor-2 (MEF-2) expression construct increased basal IL-6 promoter activity and augmented the effects of calcineurin cotransfection, while cotransfection with the MEF-2 antagonist MITR repressed calcineurin-activated IL-6 promoter activity in vitro. Surprisingly, cotransfection with a dominant-negative form of another calcineurin-activated transcription factor, nuclear factor activator of T cells (NFAT), greatly potentiated both basal and calcineurin-stimulated IL-6 promoter activity in C(2)C(12) myotubes. Mutation of the MEF-2 DNA binding sites attenuated, while mutation of the NFAT DNA binding sites potentiated basal and calcineurin-activated IL-6 promoter activity. Finally, CREB and C/EBP were necessary for basal IL-6 promoter activity and sufficient to increase IL-6 promoter activity but had minimal roles in calcineurin-activated IL-6 promoter activity. Together, these results suggest that IL-6 transcription in skeletal muscle cells can be activated by a calcineurin-MEF-2 axis which is antagonized by NFAT.
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Affiliation(s)
- David L Allen
- Dept. of Integrative Physiology, Univ. of Colorado, Boulder, Campus Box 354, Boulder, CO 80309, USA.
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163
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Altered myoplasmic Ca(2+) handling in rat fast-twitch skeletal muscle fibres during disuse atrophy. Pflugers Arch 2009; 459:631-44. [PMID: 19997852 DOI: 10.1007/s00424-009-0764-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 11/11/2009] [Accepted: 11/13/2009] [Indexed: 10/20/2022]
Abstract
Calcium-dependent signalling pathways are believed to play an important role in skeletal muscle atrophy, but whether intracellular Ca(2+) homeostasis is affected in that situation remains obscure. We show here that there is a 20% atrophy of the fast-type flexor digitorum brevis (FDB) muscle in rats hind limb unloaded (HU) for 2 weeks, with no change in fibre type distribution. In voltage-clamp experiments, the amplitude of the slow Ca(2+) current was found similar in fibres from control and HU animals. In fibres loaded with the Ca(2+) dye indo-1, the value for the rate of [Ca(2+)] decay after the end of 5-100-ms-long voltage-clamp depolarisations from -80 to +10 mV was found to be 30-50% lower in fibres from HU animals. This effect was consistent with a reduced contribution of both saturable and non-saturable components of myoplasmic Ca(2+) removal. However, there was no change in the relative amount of parvalbumin, and type 1 sarco-endoplasmic reticulum Ca(2+)-ATPase was increased by a factor of three in the atrophied muscles. Confocal imaging of mitochondrial membrane potential showed that atrophied FDB fibres had significantly depolarized mitochondria as compared to control fibres. Depolarization of mitochondria in control fibres with carbonyl cyanide-p-trifluoromethoxyphenylhydrazone induced a slowing of the decay of [Ca(2+)] transients accompanied by an increase in resting [Ca(2+)] and a reduction of the peak amplitude of the transients. Overall results provide the first functional evidence for severely altered intracellular Ca(2+) removal capabilities in atrophied fast-type muscle fibres and highlight the possible contribution of reduced mitochondrial polarisation.
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164
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Young RL, Sweeney MJ, Badyaev AV. Morphological diversity and ecological similarity: versatility of muscular and skeletal morphologies enables ecological convergence in shrews. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2009.01664.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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165
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Eivers SS, McGivney BA, Fonseca RG, MacHugh DE, Menson K, Park SD, Rivero JLL, Taylor CT, Katz LM, Hill EW. Alterations in oxidative gene expression in equine skeletal muscle following exercise and training. Physiol Genomics 2009; 40:83-93. [PMID: 19861432 DOI: 10.1152/physiolgenomics.00041.2009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Intense selection for elite racing performance in the Thoroughbred horse (Equus caballus) has resulted in a number of adaptive physiological phenotypes relevant to exercise; however, the underlying molecular mechanisms responsible for these characteristics are not well understood. Adaptive changes in mRNA expression in equine skeletal muscle were investigated by real-time qRT-PCR for a panel of candidate exercise-response genes following a standardized incremental-step treadmill exercise test in eight untrained Thoroughbred horses. Biopsy samples were obtained from the gluteus medius before, immediately after, and 4 h after exercise. Significant (P < 0.05) differences in gene expression were detected for six genes (CKM, COX4I1, COX4I2, PDK4, PPARGC1A, and SLC2A4) 4 h after exercise. Investigation of relationships between mRNA and velocity at maximum heart rate (VHR(max)) and peak postexercise plasma lactate concentration ([La]T(1)) revealed significant (P < 0.05) associations with postexercise COX4I1 and PPARCG1A expression and between [La]T(1) and basal COX4I1 expression. Gene expression changes were investigated in a second cohort of horses after a 10 mo period of training. In resting samples, COX4I1 gene expression had significantly increased following training, and, after exercise, significant differences were identified for COX4I2, PDK4, and PPARGC1A. Significant relationships with VHR(max) and [La]T(1) were detected for PPARGC1A and COX4I1. These data highlight the roles of genes responsible for the regulation of oxygen-dependent metabolism, glucose metabolism, and fatty acid utilization in equine skeletal muscle adaptation to exercise.
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Affiliation(s)
- Suzanne S Eivers
- Animal Genomics Laboratory, University College Dublin School of Agriculture, Food Science and Veterinary Medicine, Dublin, Ireland
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166
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Skeletal muscle response to inflammation—Lessons for chronic obstructive pulmonary disease. Crit Care Med 2009; 37:S372-83. [DOI: 10.1097/ccm.0b013e3181b6ea1d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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167
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Abstract
In the past decade, growing recognition of the importance of motor activity for the development and maintenance of central nervous system pathways and for recovery of function post injury has provided new avenues for rehabilitation. Physical therapy is likely to have a prominent role in stimulating neuroplastic changes in damaged developing nervous systems that may finally alter the natural history of these disorders, which has not yet been possible. In this article, we discuss the scientific evidence for various physical therapy treatment options for children with cerebral palsy. Newer, more intense, and task-related exercise programs show the strongest level of evidence. Traditional approaches and newer ''packaged'' approaches have failed to provide evidence of superiority. Their continued prevalence among clinicians is puzzling and disconcerting, as evidence supporting other approaches continues to accumulate.
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Affiliation(s)
- Diane L Damiano
- National Institutes of Health, Rehabilitation Medicine Department, Bethesda, Maryland 20892, USA.
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168
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Jorquera G, Juretić N, Jaimovich E, Riveros N. Membrane depolarization induces calcium-dependent upregulation of Hsp70 and Hmox-1 in skeletal muscle cells. Am J Physiol Cell Physiol 2009; 297:C581-90. [PMID: 19570893 DOI: 10.1152/ajpcell.00167.2009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Heat shock proteins (HSPs) are a conserved family of cytoprotective polypeptides, synthesized by cells in response to stress. Hsp70 and heme oxygenase 1 (Hmox-1) are induced by a variety of cellular stressors in skeletal muscle, playing a role in long-term adaptations and muscle fibers regeneration. Though HSPs expression after exercise has been intensely investigated, the molecular mechanisms concerning Hsp70 and Hmox-1 induction are poorly understood. The aim of this work was to investigate the involvement of calcium in Hsp70 and Hmox-1 expression upon depolarization of skeletal muscle cells. We observed that depolarization of myotubes increased both mRNA levels and protein expression for Hsp70 and Hmox-1. Stimulation in the presence of intracellular calcium chelator BAPTA-AM resulted in a complete inhibition of Hsp70-induced expression. It is known that inositol-1,4,5-trisphophate (IP(3))-mediated slow Ca(2+) transients, evoked by membrane depolarization, are involved in the regulation of gene expression. Here we demonstrated that inhibition of IP(3)-dependent calcium signals decreased both Hsp70 mRNA induction and Hsp70 and Hmox-1 protein expression. Inhibitors of calcium-dependent protein kinase C also abolished Hsp70 mRNA induction. Our results provide evidence that membrane depolarization increases Hsp70 and Hmox-1 expression in cultured skeletal muscle cells, which the effect is critically dependent on Ca(2+) released from IP(3)-sensitive intracellular stores and that it involves PKC as an upstream effector in Hsp70 mRNA-induced expression.
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Affiliation(s)
- Gonzalo Jorquera
- Centro de Estudios Moleculares de la Célula, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago 7, Chile
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169
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Ahmetov II, Williams AG, Popov DV, Lyubaeva EV, Hakimullina AM, Fedotovskaya ON, Mozhayskaya IA, Vinogradova OL, Astratenkova IV, Montgomery HE, Rogozkin VA. The combined impact of metabolic gene polymorphisms on elite endurance athlete status and related phenotypes. Hum Genet 2009; 126:751-61. [DOI: 10.1007/s00439-009-0728-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 07/25/2009] [Indexed: 11/30/2022]
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170
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Flueck M. Tuning of mitochondrial pathways by muscle work: from triggers to sensors and expression signatures. Appl Physiol Nutr Metab 2009; 34:447-53. [PMID: 19448713 DOI: 10.1139/h09-034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Performance of striated muscle relies on the nerve-driven activation of the sarcomeric motor and coupled energy supply lines. This biological engine is unique; its mechanical and metabolic characteristics are not fixed, but are tailored by functional demand with exercise. This remodelling is specific for the imposed muscle stimulus. This is illustrated by the increase in local oxidative capacity with highly repetitive endurance training vs. the preferential initiation of sarcomerogenesis with strength training regimes, where high-loading increments are imposed. The application of molecular biology has provided unprecedented insight into the pathways that govern muscle plasticity. Time-course analysis indicates that the adjustments to muscle work involve a broad regulation of transcript expression during the recovery phase from a single bout of exercise. Highly resolving microarray analysis demonstrates that the specificity of an endurance-exercise stimulus is reflected by the signature of the transcriptome response after muscle work. A quantitative match in mitochondrial transcript adjustments and mitochondrial volume density after endurance training suggests that the gradual accumulation of expressional microadaptations underlies the promotion of fatigue resistance with training. This regulation is distinguished from control of muscle growth via the load-dependent activation of sarcomerogenesis. Discrete biochemical signalling systems have evolved that sense metabolic perturbations during exercise and trigger a specific expression program, which instructs the remodelling of muscle makeup. A drop in muscle oxygen tension and metabolite perturbations with exercise are recognized as important signals in the genome-mediated remodelling of the metabolic muscle phenotype in humans.
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Affiliation(s)
- Martin Flueck
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Oxford Road, Manchester M15 6BH, UK.
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171
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Gerth N, Sum S, Jackson S, Starck JM. Muscle plasticity of Inuit sled dogs in Greenland. ACTA ACUST UNITED AC 2009; 212:1131-9. [PMID: 19329747 DOI: 10.1242/jeb.028324] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study examined flexible adjustments of skeletal muscle size, fiber structure, and capillarization in Inuit sled dogs responding to seasonal changes in temperature, exercise and food supply. Inuit dogs pull sleds in winter and are fed regularly throughout this working season. In summer, they remain chained to rocks without exercise, receiving food intermittently and often fasting for several days. We studied two dog teams in Northern Greenland (Qaanaaq) where dogs are still draught animals vital to Inuit hunters, and one dog team in Western Greenland (Qeqertarsuaq) where this traditional role has been lost. Northern Greenland dogs receive more and higher quality food than those in Western Greenland. We used ultrasonography for repeated muscle size measurements on the same individuals, and transmission electron microscopy on micro-biopsies for summer-winter comparisons of muscle histology, also within individuals. At both study sites, dogs' muscles were significantly thinner in summer than in winter - atrophy attributable to reduced fiber diameter. Sarcomeres from West Greenland dogs showed serious myofilament depletion and expansion of the sarcoplasmatic space between myofibrils during summer. At both study sites, summer samples showed fewer interfibrillar and subsarcolemmal mitochondria, and fewer lipid droplets between myofibrils, than did winter samples. In summer, capillary density was higher and inter-capillary distance smaller than in winter, but the capillary-to-fiber-ratio and number of capillaries associated with single myofibers were constant. Increased capillary density was probably a by-product of differential tissue responses to condition changes rather than a functional adaptation, because thinning of muscle fibers in summer was not accompanied by reduction in the capillary network. Thus, skeletal muscle of Inuit dogs responds flexibly to changes in functional demands. This flexibility is based on differential changes in functional components: mitochondrial numbers, lipid droplet size, and the number of contractile filaments all increase with increasing workload and food supply while the capillary network remains unchanged.
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Affiliation(s)
- Nadine Gerth
- Department of Biology II, University of Munich (LMU), 82152 Planegg-Martiensried, Germany.
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172
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Martens GA, Pipeleers D. Glucose, regulator of survival and phenotype of pancreatic beta cells. VITAMINS AND HORMONES 2009; 80:507-39. [PMID: 19251048 DOI: 10.1016/s0083-6729(08)00617-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The key role of glucose in regulating insulin release by the pancreatic beta cell population is not only dependent on acute stimulus-secretion coupling mechanisms but also on more long-term influences on beta cell survival and phenotype. Glucose serves as a major survival factor for beta cells via at least three actions: it prevents an oxidative redox state, it suppresses a mitochondrial apoptotic program that is triggered at reduced mitochondrial metabolic activity and it induces genes needed for the cellular responsiveness to glucose and to growth factors. Glucose-regulated pathways may link protein synthetic and proliferative activities, making glucose a permissive factor for beta cell proliferation, in check with metabolic needs. Conditions of inadequate glucose metabolism in beta cells are not only leading to deregulation of acute secretory responses but should also be considered as causes for increased apoptosis and reduced formation of beta cells, and loss of their normal differentiated state.
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173
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Gu J, Orr N, Park SD, Katz LM, Sulimova G, MacHugh DE, Hill EW. A genome scan for positive selection in thoroughbred horses. PLoS One 2009; 4:e5767. [PMID: 19503617 PMCID: PMC2685479 DOI: 10.1371/journal.pone.0005767] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 01/22/2009] [Indexed: 01/10/2023] Open
Abstract
Thoroughbred horses have been selected for exceptional racing performance resulting in system-wide structural and functional adaptations contributing to elite athletic phenotypes. Because selection has been recent and intense in a closed population that stems from a small number of founder animals Thoroughbreds represent a unique population within which to identify genomic contributions to exercise-related traits. Employing a population genetics-based hitchhiking mapping approach we performed a genome scan using 394 autosomal and X chromosome microsatellite loci and identified positively selected loci in the extreme tail-ends of the empirical distributions for (1) deviations from expected heterozygosity (Ewens-Watterson test) in Thoroughbred (n = 112) and (2) global differentiation among four geographically diverse horse populations (F(ST)). We found positively selected genomic regions in Thoroughbred enriched for phosphoinositide-mediated signalling (3.2-fold enrichment; P<0.01), insulin receptor signalling (5.0-fold enrichment; P<0.01) and lipid transport (2.2-fold enrichment; P<0.05) genes. We found a significant overrepresentation of sarcoglycan complex (11.1-fold enrichment; P<0.05) and focal adhesion pathway (1.9-fold enrichment; P<0.01) genes highlighting the role for muscle strength and integrity in the Thoroughbred athletic phenotype. We report for the first time candidate athletic-performance genes within regions targeted by selection in Thoroughbred horses that are principally responsible for fatty acid oxidation, increased insulin sensitivity and muscle strength: ACSS1 (acyl-CoA synthetase short-chain family member 1), ACTA1 (actin, alpha 1, skeletal muscle), ACTN2 (actinin, alpha 2), ADHFE1 (alcohol dehydrogenase, iron containing, 1), MTFR1 (mitochondrial fission regulator 1), PDK4 (pyruvate dehydrogenase kinase, isozyme 4) and TNC (tenascin C). Understanding the genetic basis for exercise adaptation will be crucial for the identification of genes within the complex molecular networks underlying obesity and its consequential pathologies, such as type 2 diabetes. Therefore, we propose Thoroughbred as a novel in vivo large animal model for understanding molecular protection against metabolic disease.
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Affiliation(s)
- Jingjing Gu
- Animal Genomics Laboratory, School of Agriculture, Food Science and Veterinary Medicine, College of Life Sciences, University College Dublin, Belfield, Dublin, Ireland
| | - Nick Orr
- Animal Genomics Laboratory, School of Agriculture, Food Science and Veterinary Medicine, College of Life Sciences, University College Dublin, Belfield, Dublin, Ireland
- The Breakthrough Breast Cancer Research Centre, Chester Beatty Laboratories, The Institute of Cancer Research, London, United Kingdom
| | - Stephen D. Park
- Animal Genomics Laboratory, School of Agriculture, Food Science and Veterinary Medicine, College of Life Sciences, University College Dublin, Belfield, Dublin, Ireland
| | - Lisa M. Katz
- University Veterinary Hospital, School of Agriculture, Food Science and Veterinary Medicine, College of Life Sciences, University College Dublin, Belfield, Dublin, Ireland
| | - Galina Sulimova
- Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia
| | - David E. MacHugh
- Animal Genomics Laboratory, School of Agriculture, Food Science and Veterinary Medicine, College of Life Sciences, University College Dublin, Belfield, Dublin, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Emmeline W. Hill
- Animal Genomics Laboratory, School of Agriculture, Food Science and Veterinary Medicine, College of Life Sciences, University College Dublin, Belfield, Dublin, Ireland
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174
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miRNA in the regulation of skeletal muscle adaptation to acute endurance exercise in C57Bl/6J male mice. PLoS One 2009; 4:e5610. [PMID: 19440340 PMCID: PMC2680038 DOI: 10.1371/journal.pone.0005610] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 04/24/2009] [Indexed: 01/13/2023] Open
Abstract
MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNA species involved in post-transcriptional gene regulation. In vitro studies have identified a small number of skeletal muscle-specific miRNAs which play a crucial role in myoblast proliferation and differentiation. In skeletal muscle, an acute bout of endurance exercise results in the up-regulation of transcriptional networks that regulate mitochondrial biogenesis, glucose and fatty acid metabolism, and skeletal muscle remodelling. The purpose of this study was to assess the expressional profile of targeted miRNA species following an acute bout of endurance exercise and to determine relationships with previously established endurance exercise responsive transcriptional networks. C57Bl/6J wild-type male mice (N = 7/group) were randomly assigned to either sedentary or forced-endurance exercise (treadmill run @ 15 m/min for 90 min) group. The endurance exercise group was sacrificed three hours following a single bout of exercise. The expression of miR- 181, 1, 133, 23, and 107, all of which have been predicted to regulate transcription factors and co-activators involved in the adaptive response to exercise, was measured in quadriceps femoris muscle. Endurance exercise significantly increased the expression of miR-181, miR-1, and miR-107 by 37%, 40%, and 56%, respectively, and reduced miR-23 expression by 84% (P≤0.05 for all), with no change in miR-133. Importantly, decreased expression of miRNA-23, a putative negative regulator of PGC-1α was consistent with increased expression of PGC-1α mRNA and protein along with several downstream targets of PGC-1α including ALAS, CS, and cytochrome c mRNA. PDK4 protein content remains unaltered despite an increase in its putative negative regulator, miR-107, and PDK4 mRNA expression. mRNA expression of miRNA processing machinery (Drosha, Dicer, and DGCR8) remained unchanged. We conclude that miRNA-mediated post-transcriptional regulation is potentially involved in the complex regulatory networks that govern skeletal muscle adaptation to endurance exercise in C57Bl/6J male mice.
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175
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Skovgaard D, Kjaer M, Madsen J, Kjaer A. Noninvasive 64Cu-ATSM and PET/CT assessment of hypoxia in rat skeletal muscles and tendons during muscle contractions. J Nucl Med 2009; 50:950-8. [PMID: 19443591 DOI: 10.2967/jnumed.109.062216] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED The purpose of the present study was to investigate exercise-related changes in oxygenation in rat skeletal muscles and tendons noninvasively with PET/CT and the hypoxia-selective tracer (64)Cu-diacetyl bis(N(4)-methylthiosemicarbazone) (ATSM) and to quantitatively study concomitant changes in gene expression of 2 hypoxia-related genes, hypoxia-inducible factor 1alpha (HIF1alpha) and carbonic anhydrase III (CAIII). METHODS Two groups of Wistar rats performed 1-leg contractions of the calf muscle by electrostimulation of the sciatic nerve. After 10 min of muscle contractions, (64)Cu-ATSM was injected and contractions were continued for 20 min. PET/CT of both hind limbs was performed immediately and 1 h after the contractions. The exercise group (n = 8) performed only muscle contractions as described, whereas the other group, exercise plus cuff (n = 8), in addition underwent cuff-induced hypoxia during the first PET/CT scan. Standardized uptake values (SUVs) were calculated for the Achilles tendons and triceps surae muscles and were correlated to gene expression of HIF1alpha and CAIII using real-time polymerase chain reaction. RESULTS Immediately after the contractions, uptake of (64)Cu-ATSM was significantly increased, by approximately 1.5-fold in muscles and 1.3-fold in tendons, compared with resting conditions. The significant increase was maintained in late PET scans in stimulated muscles and tendons independently of cuff application. In muscles, SUV correlated significantly with gene expression of HIF1alpha and CAIII, whereas this coherence was not found in tendons. CONCLUSION We found enhanced uptake of (64)Cu-ATSM in both early and late PET scans, thereby supporting the possibility that (64)Cu-ATSM registers exercise-induced transient hypoxia in both skeletal muscles and force-transmitting tendons. The fact that skeletal muscles but not tendons showed upregulation of HIF1alpha and CAIII could indicate that healthy tendons are less responsive than skeletal muscles to low levels of oxygen.
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Affiliation(s)
- Dorthe Skovgaard
- Institute of Sports Medicine, Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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176
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STEPTO NIGELK, COFFEY VERNONG, CAREY ANDREWL, PONNAMPALAM ANNAP, CANNY BENEDICTJ, POWELL DAVID, HAWLEY JOHNA. Global Gene Expression in Skeletal Muscle from Well-Trained Strength and Endurance Athletes. Med Sci Sports Exerc 2009; 41:546-65. [DOI: 10.1249/mss.0b013e31818c6be9] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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177
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Moreno-Sánchez N, Díaz C, Carabaño MJ, Rueda J, Rivero JLL. A comprehensive characterisation of the fibre composition and properties of a limb (flexor digitorum superficialis, membri thoraci) and a trunk (psoas major) muscle in cattle. BMC Cell Biol 2008; 9:67. [PMID: 19077313 PMCID: PMC2630315 DOI: 10.1186/1471-2121-9-67] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 12/15/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The fibre type attributes and the relationships among their properties play an important role in the differences in muscle capabilities and features. Comprehensive characterisation of the skeletal muscles should study the degree of association between them and their involvement in muscle functionality. The purposes of the present study were to characterise the fibre type composition of a trunk (Psoas major, PM) and a limb (Flexor digitorum, membri thoraci, FD) muscle in the bovine species and to study the degree of coordination among contractile, metabolic and histological properties of fibre types. Immunohistochemical, histochemical and histological techniques were used. RESULTS The fibre type composition was delineated immunohistochemically in calf muscle samples, identifying three pure (I, IIA, and IIX) and two hybrid type fibres (I+IIA, and IIAX). Most of the fibres in FD were types I and IIA, while pure IIX were absent. All fibre types were found in PM, the IIX type being the most frequent. Compared to other species, small populations of hybrid fibres were detected. The five fibre types, previously identified, were ascribed to three different acid and alkaline mATPase activity patterns. Type I fibres had the highest oxidative capacity and the lowest glycolytic capacity. The reverse was true for the IIX fibres, whereas the type IIA fibres showed intermediate properties. Regarding the histological properties, type I fibres tended to be more capillarised than the II types. Correlations among contractile, metabolic and histological features on individual fibres were significantly different from zero (r values varied between -0.31 and 0.78). Hybrid fibre values were positioned between their corresponding pure types, and their positions were different regarding their metabolic and contractile properties. CONCLUSION Coordination among the contractile, metabolic and histological properties of fibres has been observed. However, the magnitude of the correlation among them is always below 0.8, suggesting that the properties of muscles are not fully explained by the fibre composition. These results support the concept that, to some extent, muscle plasticity can be explained by the fibre type composition, and by the properties derived from their metabolic and histological profiles.
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Affiliation(s)
- Natalia Moreno-Sánchez
- Departamento de Mejora Genética Animal, INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria), Ctra. A Coruña km 7.2, 28040 Madrid, Spain
| | - Clara Díaz
- Departamento de Mejora Genética Animal, INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria), Ctra. A Coruña km 7.2, 28040 Madrid, Spain
| | - María J Carabaño
- Departamento de Mejora Genética Animal, INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria), Ctra. A Coruña km 7.2, 28040 Madrid, Spain
| | - Julia Rueda
- Departamento de Genética, Facultad de Biología, Universidad Complutense de Madrid, José Antonio Novais 2, 28040 Madrid, Spain
| | - José-Luis L Rivero
- Laboratorio de Biopatología Muscular, Departamento de Anatomía y Anatomía Patológica Comparadas, Facultad de Veterinaria, Universidad de Córdoba, Ctra. Madrid-Cádiz km 396, 14071 Córdoba, Spain
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178
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Ukropec J, Ukropcova B, Kurdiova T, Gasperikova D, Klimes I. Adipose tissue and skeletal muscle plasticity modulates metabolic health. Arch Physiol Biochem 2008; 114:357-68. [PMID: 19016045 DOI: 10.1080/13813450802535812] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Obesity, accumulation of adipose tissue, develops when energy intake exceeds energy expenditure. Adipose tissue is essential for buffering the differences between energy intake and expenditure by accumulating lipids while skeletal muscle is the energy burning machine. Here we adopted the concept that (i) adipose tissue ability to regulate the storage capacity for lipids as well as (ii) dynamic regulation of muscle and adipose tissue secretory and metabolic activity is important for maintaining the metabolic health. This might be at least in part related to tissue plasticity, a phenomenon enabling dynamic modulation of the tissue phenotype in different physiological and pathophysiological situations. Recent advances in our understanding of the complex endocrine function of adipose tissue in regulating lipid metabolism, adipogenesis, angiogenesis, extracellular matrix remodelling, inflammation and oxidative stress prompted us to review the role of tissue plasticity--dynamic changes in adipose tissue and skeletal muscle metabolic and endocrine phenotype--in determining the difference between metabolic health and disease.
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Affiliation(s)
- Jozef Ukropec
- Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
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179
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Flück M. Unraveling the molecular underpinning of nature and nurture of aerobic fitness. Physiol Genomics 2008; 35:210-2. [DOI: 10.1152/physiolgenomics.90349.2008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Martin Flück
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, United Kingdom
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180
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Green HJ, Bombardier E, Burnett M, Iqbal S, D'Arsigny CL, O'Donnell DE, Ouyang J, Webb KA. Organization of metabolic pathways in vastus lateralis of patients with chronic obstructive pulmonary disease. Am J Physiol Regul Integr Comp Physiol 2008; 295:R935-41. [DOI: 10.1152/ajpregu.00167.2008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to determine whether patients with chronic obstructive lung disease (COPD) display differences in organization of the metabolic pathways and segments involved in energy supply compared with healthy control subjects. Metabolic pathway potential, based on the measurement of the maximal activity (Vmax) of representative enzymes, was assessed in tissue extracted from the vastus lateralis in seven patients with COPD (age 67 ± 4 yr; FEV1/FVC = 44 ± 3%, where FEV1is forced expiratory volume in 1 s and FVC is forced vital capacity; means ± SE) and nine healthy age-matched controls (age 68 ± 2 yr; FEV1/FVC = 75 ± 2%). Compared with control, the COPD patients displayed lower ( P < 0.05) Vmax(mol·kg protein−1·h−1) for cytochrome c oxidase (COX; 21.2 ± 2.0 vs. 28.7 ± 2.2) and 3-hydroxyacyl-CoA dehydrogenase (HADH; 2.54 ± 0.14 vs. 3.74 ± 0.12) but not citrate synthase (CS; 2.20 ± 0.16 vs. 3.19 ± 0.5). While no differences between groups were observed in Vmaxfor creatine phosphokinase, phosphorylase (PHOSPH), phosphofructokinase (PFK), pyruvate kinase, and lactate dehydrogenase, hexokinase (HEX) was elevated in COPD ( P < 0.05). Enzyme activity ratios were higher ( P < 0.05) for HEX/CS, HEX/COX, PHOSPH/HADH and PFK/HADH in COPD compared with control. It is concluded that COPD patients exhibit a reduced potential for both the electron transport system and fat oxidation and an increased potential for glucose phosphorylation while the potential for glycogenolysis and glycolysis remains normal. A comparison of enzyme ratios indicated greater potentials for glucose phosphorylation relative to the citric acid cycle and the electron transport chain and glycogenolysis and glycolysis relative to β-oxidation.
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181
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Brooks SV, Vasilaki A, Larkin LM, McArdle A, Jackson MJ. Repeated bouts of aerobic exercise lead to reductions in skeletal muscle free radical generation and nuclear factor kappaB activation. J Physiol 2008; 586:3979-90. [PMID: 18591188 DOI: 10.1113/jphysiol.2008.155382] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Chronic exercise improves endurance and skeletal muscle oxidative capacity. Despite the potential importance of reactive oxygen species (ROS) generated during exercise as regulators of these adaptations, the effect of repeated bouts of aerobic exercise on ROS generation by skeletal muscles during contractions has not been examined. Our aim was to establish the impact of repeated treadmill running exercise on muscle ROS generation and activation of redox-sensitive transcription factors. Following 8 weeks of treadmill running, mice displayed an improvement in running speed that was associated with an enhanced ability of gastrocnemius (GTN) muscles to maintain force during a protocol of isometric contractions. In contrast to GTN muscles of cage-sedentary (Sed) mice, muscles from exercised (Exer) mice did not release superoxide or nitric oxide during the isometric contractions. For male mice, basal levels of nuclear factor kappaB (NFkappaB) and activator protein-1 (AP-1) DNA binding were increased by treadmill running, and the contraction-induced activation of NFkappaB and AP-1 observed in muscles of Sed mice was absent in Exer muscles. Also in contrast to Sed muscles, Exer muscles displayed no reductions in glutathione or protein thiol levels in response to contraction. Our observations of decreases for Exer compared with Sed muscles in contraction-induced (i) ROS generation, (ii) activation of redox-sensitive signalling pathways, and (iii) ROS stress suggest that exercise conditioning enhances the ability of skeletal muscle to readily and rapidly detoxify ROS and/or reduces ROS generation, providing protection from ROS-induced damage and reducing signals that might act to mediate further unnecessary adaptations.
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Affiliation(s)
- Susan V Brooks
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA.
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182
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Trepp R, Flück M, Stettler C, Boesch C, Ith M, Kreis R, Hoppeler H, Howald H, Schmid JP, Diem P, Christ ER. Effect of GH on human skeletal muscle lipid metabolism in GH deficiency. Am J Physiol Endocrinol Metab 2008; 294:E1127-34. [PMID: 18413676 DOI: 10.1152/ajpendo.00010.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adult-onset growth hormone (GH) deficiency (GHD) is associated with insulin resistance and decreased exercise capacity. Intramyocellular lipids (IMCL) depend on training status, diet, and insulin sensitivity. Using magnetic resonance spectroscopy, we studied IMCL content following physical activity (IMCL-depleted) and high-fat diet (IMCL-repleted) in 15 patients with GHD before and after 4 mo of GH replacement therapy (GHRT) and in 11 healthy control subjects. Measurements of insulin resistance and exercise capacity were performed and skeletal muscle biopsies were carried out to assess expression of mRNA of key enzymes involved in skeletal muscle lipid metabolism by real-time PCR and ultrastructure by electron microscopy. Compared with control subjects, patients with GHD showed significantly higher difference between IMCL-depleted and IMCL-repleted. GHRT resulted in an increase in skeletal muscle mRNA expression of IGF-I, hormone-sensitive lipase, and a tendency for an increase in fatty acid binding protein-3. Electron microscopy examination did not reveal significant differences after GHRT. In conclusion, variation of IMCL may be increased in patients with GHD compared with healthy control subjects. Qualitative changes within the skeletal muscle (i.e., an increase in free fatty acids availability from systemic and/or local sources) may contribute to the increase in insulin resistance and possibly to the improvement of exercise capacity after GHRT. The upregulation of IGF-I mRNA suggests a paracrine/autocrine role of IGF-I on skeletal muscle.
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Affiliation(s)
- Roman Trepp
- Division of Endocrinology, Diabetology and Clinical Nutrition, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
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183
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Hayward LJ, Kim JS, Lee MY, Zhou H, Kim JW, Misra K, Salajegheh M, Wu FF, Matsuda C, Reid V, Cros D, Hoffman EP, Renaud JM, Cannon SC, Brown RH. Targeted mutation of mouse skeletal muscle sodium channel produces myotonia and potassium-sensitive weakness. J Clin Invest 2008; 118:1437-49. [PMID: 18317596 DOI: 10.1172/jci32638] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 01/16/2008] [Indexed: 11/17/2022] Open
Abstract
Hyperkalemic periodic paralysis (HyperKPP) produces myotonia and attacks of muscle weakness triggered by rest after exercise or by K+ ingestion. We introduced a missense substitution corresponding to a human familial HyperKPP mutation (Met1592Val) into the mouse gene encoding the skeletal muscle voltage-gated Na+ channel NaV1.4. Mice heterozygous for this mutation exhibited prominent myotonia at rest and muscle fiber-type switching to a more oxidative phenotype compared with controls. Isolated mutant extensor digitorum longus muscles were abnormally sensitive to the Na+/K+ pump inhibitor ouabain and exhibited age-dependent changes, including delayed relaxation and altered generation of tetanic force. Moreover, rapid and sustained weakness of isolated mutant muscles was induced when the extracellular K+ concentration was increased from 4 mM to 10 mM, a level observed in the muscle interstitium of humans during exercise. Mutant muscle recovered from stimulation-induced fatigue more slowly than did control muscle, and the extent of recovery was decreased in the presence of high extracellular K+ levels. These findings demonstrate that expression of the Met1592ValNa+ channel in mouse muscle is sufficient to produce important features of HyperKPP, including myotonia, K+-sensitive paralysis, and susceptibility to delayed weakness during recovery from fatigue.
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Affiliation(s)
- Lawrence J Hayward
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
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184
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Bellinger AM, Mongillo M, Marks AR. Stressed out: the skeletal muscle ryanodine receptor as a target of stress. J Clin Invest 2008; 118:445-53. [PMID: 18246195 DOI: 10.1172/jci34006] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Over the past century, understanding the mechanisms underlying muscle fatigue and weakness has been the focus of much investigation. However, the dominant theory in the field, that lactic acidosis causes muscle fatigue, is unlikely to tell the whole story. Recently, dysregulation of sarcoplasmic reticulum (SR) Ca(2+) release has been associated with impaired muscle function induced by a wide range of stressors, from dystrophy to heart failure to muscle fatigue. Here, we address current understandings of the altered regulation of SR Ca(2+) release during chronic stress, focusing on the role of the SR Ca(2+) release channel known as the type 1 ryanodine receptor.
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Affiliation(s)
- Andrew M Bellinger
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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185
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Hilber K. Skeletal myocyte plasticity: basis for improved therapeutic potential? Curr Opin Pharmacol 2008; 8:327-32. [PMID: 18329336 DOI: 10.1016/j.coph.2008.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 01/18/2008] [Accepted: 01/25/2008] [Indexed: 12/25/2022]
Abstract
Skeletal muscle tissue exhibits a remarkable capacity to regenerate after injury and to adapt its properties in response to altered functional demands or environmental pressure. This potential renders skeletal myocytes especially attractive candidates to be used in therapeutic strategies. Besides the well-described adaptability of skeletal myocytes in terms of contractile function and metabolic profile, more recent research has revealed that the electrophysiological properties of myocytes are also subject to significant changes both under physiological conditions and in pathophysiological situations. A better understanding of skeletal myocyte plasticity, its regulation and its forced induction could improve existing therapeutic approaches and may pave the way for new therapeutic strategies.
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Affiliation(s)
- Karlheinz Hilber
- Center of Biomolecular Medicine and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria.
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186
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Rizzo NS, Ruiz JR, Oja L, Veidebaum T, Sjöström M. Associations between physical activity, body fat, and insulin resistance (homeostasis model assessment) in adolescents: the European Youth Heart Study. Am J Clin Nutr 2008; 87:586-92. [PMID: 18326595 DOI: 10.1093/ajcn/87.3.586] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND More and better data are needed to understand the action of physical activity (PA) on insulin resistance and the concomitant relation with body fat in adolescence. OBJECTIVE We examined the relation between total PA and intensity levels with insulin resistance under special consideration of waist circumference and skinfold thickness. DESIGN This was a cross-sectional study of 613 adolescents (352 girls, 261 boys) with a mean (+/-SD) age of 15.5 +/- 0.5 y from Sweden and Estonia. Total, low, moderate, and vigorous PA was measured by accelerometry. Body fat estimators included waist circumference and the sum of 5 skinfold thicknesses. Fasting insulin and glucose were measured, and insulin resistance was calculated according to the homeostasis model assessment (HOMA). Linear regression analysis and analysis of covariance were used to determine the association between PA and insulin resistance while considering body fat. All estimates were adjusted for sex, country, pubertal status, and indicators of body fat when applicable. RESULTS Total, moderate, and vigorous PA were inversely correlated with HOMA. Body fat estimators were positively correlated with HOMA. Significant contrasts in HOMA concentrations were seen when comparing the lower 2 tertiles with the upper tertile of PA indicators. Repeating the analysis with body fat estimators showed significant contrasts in HOMA concentrations when comparing the lower tertiles with the upper tertile. CONCLUSION In view of an increase in obesity in young people, the results accentuate the role of PA in sustaining metabolic balance in adolescence and the potential benefit of an increase of time spent at higher PA levels for youth with relatively elevated amounts of body fat.
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Affiliation(s)
- Nico S Rizzo
- Unit for Preventive Nutrition, Department of Biosciences and Nutrition, NOVUM, Karolinska Institutet, Huddinge, Sweden.
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187
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Daussin FN, Zoll J, Ponsot E, Dufour SP, Doutreleau S, Lonsdorfer E, Ventura-Clapier R, Mettauer B, Piquard F, Geny B, Richard R. Training at high exercise intensity promotes qualitative adaptations of mitochondrial function in human skeletal muscle. J Appl Physiol (1985) 2008; 104:1436-41. [PMID: 18292295 DOI: 10.1152/japplphysiol.01135.2007] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
This study explored mitochondrial capacities to oxidize carbohydrate and fatty acids and functional optimization of mitochondrial respiratory chain complexes in athletes who regularly train at high exercise intensity (ATH, n = 7) compared with sedentary (SED, n = 7). Peak O(2) uptake (Vo(2max)) was measured, and muscle biopsies of vastus lateralis were collected. Maximal O(2) uptake of saponin-skinned myofibers was evaluated with several metabolic substrates [glutamate-malate (V(GM)), pyruvate (V(Pyr)), palmitoyl carnitine (V(PC))], and the activity of the mitochondrial respiratory complexes II and IV were assessed using succinate (V(s)) and N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride (V(TMPD)), respectively. Vo(2max) was higher in ATH than in SED (57.8 +/- 2.2 vs. 31.4 +/- 1.3 ml.min(-1).kg(-1), P < 0.001). V(GM) was higher in ATH than in SED (8.6 +/- 0.5 vs. 3.3 +/- 0.3 micromol O(2).min(-1).g dry wt(-1), P < 0.001). V(Pyr) was higher in ATH than in SED (8.7 +/- 1.0 vs. 5.5 +/- 0.2 micromol O(2).min(-1).g dry wt(-1), P < 0.05), whereas V(PC) was not significantly different (5.3 +/- 0.9 vs. 4.4 +/- 0.5 micromol O(2).min(-1).g dry wt(-1)). V(S) was higher in ATH than in SED (11.0 +/- 0.6 vs. 6.0 +/- 0.3 micromol O(2).min(-1).g dry wt(-1), P < 0.001), as well as V(TMPD) (20.1 +/- 1.0 vs. 16.2 +/- 3.4 micromol O(2).min(-1).g dry wt(-1), P < 0.05). The ratios V(S)/V(GM) (1.3 +/- 0.1 vs. 2.0 +/- 0.1, P < 0.001) and V(TMPD)/V(GM) (2.4 +/- 1.0 vs. 5.2 +/- 1.8, P < 0.01) were lower in ATH than in SED. In conclusion, comparison of ATH vs. SED subjects suggests that regular endurance training at high intensity promotes the enhancement of maximal mitochondrial capacities to oxidize carbohydrate rather than fatty acid and induce specific adaptations of the mitochondrial respiratory chain at the level of complex I.
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Affiliation(s)
- Frédéric N Daussin
- Service de Physiologie et d'Explorations Fonctionnelles, Hôpital Civil, 1 Place de l'Hôpital, F-67091 Strasbourg Cedex, France
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188
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Chiquet M, Tunç-Civelek V, Sarasa-Renedo A. Gene regulation by mechanotransduction in fibroblasts. Appl Physiol Nutr Metab 2008; 32:967-73. [PMID: 18059623 DOI: 10.1139/h07-053] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mechanical forces are important for connective tissue homeostasis. How do fibroblasts sense mechanical stress and how do they translate this information into an adaptive remodeling of the extracellular matrix (ECM)? Tenascin-C is rapidly induced in vivo by loading muscles and in vitro by stretching fibroblasts. Regulation of tenascin-C expression by mechanical signals occurs at the transcriptional level. Integrin receptors physically link the ECM to the cytoskeleton and act as force transducers: intracellular signals are triggered when integrins engage with ECM, and later when forces are applied. We found that cyclic strain does not induce tenascin-C messenger ribonucleic acid (mRNA) in fibroblasts lacking the beta1-integrin chain. An important link in integrin-dependent mechanotransduction is the small guanosine 5'-triphosphatase. RhoA and its target kinase, ROCK. In fibroblasts, cyclic strain activates RhoA and thereby induces ROCK-dependent actin assembly. Interestingly, tenascin-C mRNA induction by cyclic strain was suppressed by relaxing the cytoskeleton with a ROCK inhibitor or by actin depolymerization. Conversely, chemical activators of RhoA enhanced the effect of strain both on actin dynamics and on tenascin-C expression. Thus, RhoA/ROCK-controlled actin dynamics are required for the induction of specific ECM genes by mechanical stress. These findings have implications for the understanding of regeneration and for tissue engineering.
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Affiliation(s)
- Matthias Chiquet
- ITI Research Institute for Dental and Skeletal Biology, University of Bern, Murtenstrasse 35, CH-3010 Bern, Switzerland.
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189
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Wåhlin Larsson B, Kadi F, Ulfberg J, Piehl Aulin K. Skeletal Muscle Morphology and Aerobic Capacity in Patients with Obstructive Sleep Apnoea Syndrome. Respiration 2008; 76:21-7. [DOI: 10.1159/000126492] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 01/14/2008] [Indexed: 01/06/2023] Open
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190
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Burtscher M, Brandstätter E, Gatterer H. Preacclimatization in simulated altitudes. Sleep Breath 2007; 12:109-14. [DOI: 10.1007/s11325-007-0127-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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191
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Schaeffer PJ, Nichols SD, Lindstedt SL. Chronic electrical stimulation drives mitochondrial biogenesis in skeletal muscle of a lizard, Varanus exanthematicus. J Exp Biol 2007; 210:3356-60. [PMID: 17872989 DOI: 10.1242/jeb.007088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
SUMMARY
We investigated the capacity for phenotypic plasticity of skeletal muscle from Varanus exanthematicus, the savannah monitor lizard. Iliofibularis muscle from one leg of each lizard was electrically stimulated for 8 weeks. Both stimulated and contralateral control muscles were collected and processed for electron microscopy. We used stereological analysis of muscle cross-sections to quantify the volume densities of contractile elements, sarcoplasmic reticulum, mitochondria and intracellular lipids. We found that mitochondrial volume density was approximately fourfold higher in the stimulated muscle compared to controls, which were similar to previously reported values. Sarcoplasmic reticulum volume density was reduced by an amount similar to the increase in mitochondrial volume density while the volume density of contractile elements remained unchanged. Intracellular lipid accumulation was visibly apparent in many stimulated muscle sections but the volume density of lipids did not reach a significant difference. Although monitor lizards lack the highly developed aerobic metabolism of mammals, they appear to possess the capacity for muscle plasticity.
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192
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Donoghue P, Doran P, Wynne K, Pedersen K, Dunn MJ, Ohlendieck K. Proteomic profiling of chronic low-frequency stimulated fast muscle. Proteomics 2007; 7:3417-30. [PMID: 17708595 DOI: 10.1002/pmic.200700262] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Skeletal muscle fibre transitions occur in many biological processes, in response to alterations in neuromuscular activity, in muscular disorders, during age-induced muscle wasting and in myogenesis. It was therefore of interest to perform a comprehensive proteomic profiling of muscle transformation. Chronic low-frequency stimulation of the rabbit tibialis anterior muscle represents an established model system for studying the response of fast fibres to enhanced neuromuscular activity under conditions of maximum activation. We have conducted a DIGE analysis of unstimulated control specimens versus 14- and 60-day conditioned muscles. A differential expression pattern was observed for 41 protein species with 29 increased and 12 decreased muscle proteins. Identified classes of proteins that are changed during the fast-to-slow transition process belong to the contractile machinery, ion homeostasis, excitation-contraction coupling, capillarization, metabolism and stress response. Results from immunoblotting agreed with the conversion of the metabolic, regulatory and contractile molecular apparatus to support muscle fibres with slower twitch characteristics. Besides confirming established muscle elements as reliable transition markers, this proteomics-based study has established the actin-binding protein cofilin-2 and the endothelial marker transgelin as novel biomarkers for evaluating muscle transformation.
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Affiliation(s)
- Pamela Donoghue
- Proteome Research Centre, UCD Conway Institute, University College Dublin, Dublin, Ireland
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193
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Clark KA, Bland JM, Beckerle MC. The Drosophila muscle LIM protein, Mlp84B, cooperates with D-titin to maintain muscle structural integrity. J Cell Sci 2007; 120:2066-77. [PMID: 17535853 DOI: 10.1242/jcs.000695] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Muscle LIM protein (MLP) is a cytoskeletal LIM-only protein expressed in striated muscle. Mutations in human MLP are associated with cardiomyopathy; however, the molecular mechanism by which MLP functions is not established. A Drosophila MLP homolog, mlp84B, displays many of the same features as the vertebrate protein, illustrating the utility of the fly for the study of MLP function. Animals lacking Mlp84B develop into larvae with a morphologically intact musculature, but the mutants arrest during pupation with impaired muscle function. Mlp84B displays muscle-specific expression and is a component of the Z-disc and nucleus. Preventing nuclear retention of Mlp84B does not affect its function, indicating that Mlp84B site of action is likely to be at the Z-disc. Within the Z-disc, Mlp84B is colocalized with the N-terminus of D-titin, a protein crucial for sarcomere organization and stretch mechanics. The mlp84B mutants phenotypically resemble weak D-titin mutants. Furthermore, reducing D-titin activity in the mlp84B background leads to pronounced enhancement of the mlp84B muscle defects and loss of muscle structural integrity. The genetic interactions between mlp84B and D-titin reveal a role for Mlp84B in maintaining muscle structural integrity that was not obvious from analysis of the mlp84B mutants themselves, and suggest Mlp84B and D-titin cooperate to stabilize muscle sarcomeres.
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Affiliation(s)
- Kathleen A Clark
- Huntsman Cancer Institute, Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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194
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Lucki NC, Nicolay CW. Phenotypic plasticity and functional asymmetry in response to grip forces exerted by intercollegiate tennis players. Am J Hum Biol 2007; 19:566-77. [PMID: 17546612 DOI: 10.1002/ajhb.20632] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study examined phenotypic and functional responses to extreme asymmetry in hand use, and recorded the grip forces that occur during the tennis serve to assess the forces that contribute to asymmetry. Compressive grip performance was measured for Division I collegiate tennis players (24 female, 24 male) and nonathlete college students (18 females, 17 males) during three experiments: single-repetition maximum voluntary contraction, 30 consecutive repetitions, and a 30-s static hold. Tennis players had significant asymmetry in both forearm circumference and grip strength. The dominant hand of female tennis players produced 25% more force than the opposite hand, while the difference between hands of male tennis players was 18%. However, endurance over 30-repetitions and during the 30-s hold did not significantly differ between the limbs of tennis players. No significant asymmetry in forearm measurements, grip strength, or endurance was detected between the limbs of nonathletes. Grip forces generated during the tennis serve were recorded for 4 male tennis players, using a racket with a dynamometer incorporated into the handle. Peak handgrip forces generated during the serve (150-250 N) averaged 31-44% of the maximum grip force of the participant. Tennis players have increased muscle mass and strength of the dominant limb. Moderate forces, occurring hundreds of times each match and practice, are likely the primary forces contributing to this morphological and functional asymmetry.
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Affiliation(s)
- Natasha C Lucki
- Department of Biology, University of North Carolina Asheville, Asheville, North Carolina 28804, USA
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195
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Abstract
SUMMARYNatural or artificial selection that favors higher values of a particular trait within a given population should engender an evolutionary response that increases the mean value of the trait. For this prediction to hold, the phenotypic variance of the trait must be caused in part by additive effects of alleles segregating in the population, and also the trait must not be too strongly genetically correlated with other traits that are under selection. Another prediction, rarely discussed in the literature, is that directional selection should favor alleles that increase phenotypic plasticity in the direction of selection, where phenotypic plasticity is defined as the ability of one genotype to produce more than one phenotype when exposed to different environments. This prediction has received relatively little empirical attention. Nonetheless, many laboratory experiments impose selection regimes that could allow for the evolution of enhanced plasticity (e.g. desiccation trials with Drosophila that last for several hours or days). We review one example that involved culturing of Drosophila on lemon for multiple generations and then tested for enhanced plasticity of detoxifying enzymes. We also review an example with vertebrates that involves selective breeding for high voluntary activity levels in house mice, targeting wheel-running behavior on days 5+6 of a 6-day wheel exposure. This selection regime allows for the possibility of wheel running itself or subordinate traits that support such running to increase in plasticity over days 1–4 of wheel access. Indeed, some traits, such as the concentration of the glucose transporter GLUT4 in gastrocnemius muscle, do show enhanced plasticity in the selected lines over a 5–6 day period. In several experiments we have housed mice from both the Selected (S) and Control (C) lines with or without wheel access for several weeks to test for differences in plasticity (training effects). A variety of patterns were observed, including no training effects in either S or C mice, similar changes in both the S and C lines, greater changes in the S lines but in the same direction in the C lines, and even opposite directions of change in the S and C lines. For some of the traits that show a greater training effect in the S lines, but in the same direction as in C lines, the greater effect can be explained statistically by the greater wheel running exhibited by S lines (`more pain, more gain'). For others, however, the differences seem to reflect inherently greater plasticity in the S lines (i.e. for a given amount of stimulus, such as wheel running/day, individuals in the S lines show a greater response as compared with individuals in the C lines). We suggest that any selection experiment in which the selective event is more than instantaneous should explore whether plasticity in the appropriate (adaptive) direction has increased as a component of the response to selection.
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Affiliation(s)
- Theodore Garland
- Department of Biology, University of California, Riverside, Riverside, CA 92521, USA.
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