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Sewry CA. 25th Meryon Lecture, given at the Annual Meeting of the Meryon Society, St Anne's College, Oxford, 7 th July 2023The motor unit: A chequered history. Neuromuscul Disord 2024; 39:33-36. [PMID: 38759273 DOI: 10.1016/j.nmd.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2024]
Affiliation(s)
- Caroline A Sewry
- Department of Musculoskeletal Histopathology and Wolfson Centre for Inherited Neuromuscular Diseases RJAH Orthopaedic Hospital NHS Foundation Trust, Oswestry, SY10 7AG, UK; Department of Cellular Pathology, Salford Royal Hospital NHS Foundation Trust, Northern Care Alliance, Manchester, M6 8HD, UK; Dubowitz Neuromuscular Centre, UCL Institute of Child Health and Great Ormond Street Hospital, 30 Guilford Street, London, WC1N 1EH, UK.
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Naito A, Nagatomo Y, Kawai A, Yukino-Iwashita M, Nakazawa R, Taruoka A, Takefuji A, Yasuda R, Toya T, Ikegami Y, Masaki N, Ido Y, Adachi T. The Safety and Efficacy of Sodium-Glucose Cotransporter-2 Inhibitors for Patients with Sarcopenia or Frailty: Double Edged Sword? J Pers Med 2024; 14:141. [PMID: 38392575 PMCID: PMC10890336 DOI: 10.3390/jpm14020141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/19/2024] [Accepted: 01/24/2024] [Indexed: 02/24/2024] Open
Abstract
Sodium-glucose cotransporter-2 inhibitors (SGLT-2is) show cardiovascular protective effects, regardless of the patient's history of diabetes mellitus (DM). SGLT2is suppressed cardiovascular adverse events in patients with type 2 DM, and furthermore, SGLT-2is reduced the risk of worsening heart failure (HF) events or cardiovascular death in patients with HF. Along with these research findings, SGLT-2is are recommended for patients with HF in the latest guidelines. Despite these benefits, the concern surrounding the increasing risk of body weight loss and other adverse events has not yet been resolved, especially for patients with sarcopenia or frailty. The DAPA-HF and DELIVER trials consistently showed the efficacy and safety of SGLT-2i for HF patients with frailty. However, the Rockwood frailty index that derived from a cumulative deficit model was employed for frailty assessment in these trials, which might not be suitable for the evaluation of physical frailty or sarcopenia alone. There is no fixed consensus on which evaluation tool to use or its cutoff value for the diagnosis and assessment of frailty in HF patients, or which patients can receive SGLT-2i safely. In this review, we summarize the methodology of frailty assessment and discuss the efficacy and safety of SGLT-2i for HF patients with sarcopenia or frailty.
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Affiliation(s)
- Ayami Naito
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Yuji Nagatomo
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Akane Kawai
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | | | - Ryota Nakazawa
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Akira Taruoka
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Asako Takefuji
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Risako Yasuda
- Department of Intensive Care, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Takumi Toya
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Yukinori Ikegami
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Nobuyuki Masaki
- Department of Intensive Care, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Yasuo Ido
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Takeshi Adachi
- Department of Cardiology, National Defense Medical College, Tokorozawa 359-8513, Japan
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Lloyd EM, Pinniger GJ, Murphy RM, Grounds MD. Slow or fast: Implications of myofibre type and associated differences for manifestation of neuromuscular disorders. Acta Physiol (Oxf) 2023; 238:e14012. [PMID: 37306196 DOI: 10.1111/apha.14012] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 05/30/2023] [Accepted: 06/06/2023] [Indexed: 06/13/2023]
Abstract
Many neuromuscular disorders can have a differential impact on a specific myofibre type, forming the central premise of this review. The many different skeletal muscles in mammals contain a spectrum of slow- to fast-twitch myofibres with varying levels of protein isoforms that determine their distinctive contractile, metabolic, and other properties. The variations in functional properties across the range of classic 'slow' to 'fast' myofibres are outlined, combined with exemplars of the predominantly slow-twitch soleus and fast-twitch extensor digitorum longus muscles, species comparisons, and techniques used to study these properties. Other intrinsic and extrinsic differences are discussed in the context of slow and fast myofibres. These include inherent susceptibility to damage, myonecrosis, and regeneration, plus extrinsic nerves, extracellular matrix, and vasculature, examined in the context of growth, ageing, metabolic syndrome, and sexual dimorphism. These many differences emphasise the importance of carefully considering the influence of myofibre-type composition on manifestation of various neuromuscular disorders across the lifespan for both sexes. Equally, understanding the different responses of slow and fast myofibres due to intrinsic and extrinsic factors can provide deep insight into the precise molecular mechanisms that initiate and exacerbate various neuromuscular disorders. This focus on the influence of different myofibre types is of fundamental importance to enhance translation for clinical management and therapies for many skeletal muscle disorders.
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Affiliation(s)
- Erin M Lloyd
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute, Curtin Medical School, Curtin University, Bentley, Western Australia, Australia
| | - Gavin J Pinniger
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Victoria, Australia
| | - Miranda D Grounds
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
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Abdelhafiz AH, Keegan GL, Sinclair AJ. Metabolic Characteristics of Frail Older People with Diabetes Mellitus-A Systematic Search for Phenotypes. Metabolites 2023; 13:705. [PMID: 37367862 DOI: 10.3390/metabo13060705] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/17/2023] [Accepted: 05/24/2023] [Indexed: 06/28/2023] Open
Abstract
Frailty in older people with diabetes is viewed as one homogeneous category. We previously suggested that frailty is not homogeneous and spans across a metabolic spectrum that starts with an anorexic malnourished (AM) frail phenotype and ends with a sarcopenic obese (SO) phenotype. We aimed to investigate the metabolic characteristics of frail older people with diabetes reported in the current literature to explore whether they fit into two distinctive metabolic phenotypes. We performed systematic review of studies published over the last 10 years and reported characteristics of frail older people with diabetes mellitus. A total of 25 studies were included in this systematic review. Fifteen studies reported frail patients' characteristics that could fit into an AM phenotype. This phenotype is characterised by low body weight, increased prevalence of malnutrition markers such as low serum albumin, low serum cholesterol, low Hb, low HbA1c, and increased risk of hypoglycaemia. Ten studies reported frail patients' characteristics that describe a SO phenotype. This phenotype is characterised by increased body weight, increased serum cholesterol, high HbA1c, and increased blood glucose levels. Due to significant weight loss in the AM phenotype, insulin resistance decreases, leading to a decelerated diabetes trajectory and reduced hypoglycaemic agent use or deintensification of therapy. On the other hand, in the SO phenotype, insulin resistance increases leading to accelerated diabetes trajectory and increased hypoglycaemic agent use or intensification of therapy. Current literature suggests that frailty is a metabolically heterogeneous condition that includes AM and SO phenotypes. Both phenotypes have metabolically distinctive features, which will have a different effect on diabetes trajectory. Therefore, clinical decision-making and future clinical studies should consider the metabolic heterogeneity of frailty.
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Affiliation(s)
- Ahmed H Abdelhafiz
- Department of Geriatric Medicine, Rotherham General Hospital, Moorgate Road, Rotherham S60 2UD, UK
| | - Grace L Keegan
- Department of Geriatric Medicine, Rotherham General Hospital, Moorgate Road, Rotherham S60 2UD, UK
| | - Alan J Sinclair
- Foundation for Diabetes Research in Older People, Diabetes Frail Ltd., Droitwich Spa WR9 0QH, UK
- King's College, London WC2R 2LS, UK
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Sinclair AJ, Abdelhafiz AH. Metabolic Impact of Frailty Changes Diabetes Trajectory. Metabolites 2023; 13:metabo13020295. [PMID: 36837914 PMCID: PMC9960364 DOI: 10.3390/metabo13020295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/25/2023] [Accepted: 02/13/2023] [Indexed: 02/19/2023] Open
Abstract
Diabetes mellitus prevalence increases with increasing age. In older people with diabetes, frailty is a newly emerging and significant complication. Frailty induces body composition changes that influence the metabolic state and affect diabetes trajectory. Frailty appears to have a wide metabolic spectrum, which can present with an anorexic malnourished phenotype and a sarcopenic obese phenotype. The sarcopenic obese phenotype individuals have significant loss of muscle mass and increased visceral fat. This phenotype is characterised by increased insulin resistance and a synergistic increase in the cardiovascular risk more than that induced by obesity or sarcopenia alone. Therefore, in this phenotype, the trajectory of diabetes is accelerated, which needs further intensification of hypoglycaemic therapy and a focus on cardiovascular risk reduction. Anorexic malnourished individuals have significant weight loss and reduced insulin resistance. In this phenotype, the trajectory of diabetes is decelerated, which needs deintensification of hypoglycaemic therapy and a focus on symptom control and quality of life. In the sarcopenic obese phenotype, the early use of sodium-glucose transporter-2 inhibitors and glucagon-like peptide-1 receptor agonists is reasonable due to their weight loss and cardio-renal protection properties. In the malnourished anorexic phenotype, the early use of long-acting insulin analogues is reasonable due to their weight gain and anabolic properties, regimen simplicity and the convenience of once-daily administration.
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Affiliation(s)
- Alan J. Sinclair
- Foundation for Diabetes Research in Older People (fDROP), King’s College, London WC2R 2LS, UK
| | - Ahmed H. Abdelhafiz
- Foundation for Diabetes Research in Older People (fDROP), King’s College, London WC2R 2LS, UK
- Department of Geriatric Medicine Rotherham General Hospital, Rotherham S60 2UD, UK
- Correspondence:
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Le Corre A, Caron N, Turpin NA, Dalleau G. Mechanisms underlying altered neuromuscular function in people with DPN. Eur J Appl Physiol 2023:10.1007/s00421-023-05150-2. [PMID: 36763123 DOI: 10.1007/s00421-023-05150-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 01/29/2023] [Indexed: 02/11/2023]
Abstract
Diabetes alters numerous physiological functions and can lead to disastrous consequences in the long term. Neuromuscular function is particularly affected and is impacted early, offering an opportunity to detect the onset of diabetes-related dysfunctions and follow the advancement of the disease. The role of physical training for counteracting the deleterious effects of diabetes is well accepted but at the same time, it appears difficult to reliably assess the effects of exercise on functional capacity in patients with diabetic peripheral neuropathy (DPN). In this paper, we will review the specific characteristics of various neuromuscular dysfunctions associated with diabetes according to the DPN presence or not, and their changes over time. We present several propositions regarding the onset of neuromuscular alterations in people with diabetes compared to people with DPN. It appears that motor unit loss and neuromuscular transmission impairment are among the main mechanisms explaining the considerable degradation of neuromuscular function in the transition from a diabetic to neuropathic state. Rate of force development and contractile properties could start to decrease with the onset of preferential type II fiber atrophy, commonly reported in people with DPN. Finally, Mmax amplitude could decrease with neuromuscular fatigue only in people with DPN, reflecting the fatigue-related neuromuscular transmission impairment reported in people with DPN. In this review, we show that the different neuromuscular parameters are altered at different stages of diabetes, according to the presence of DPN or not. The precise evaluation of these parameters might participate in adapting the physical training prescription.
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Affiliation(s)
- Antonin Le Corre
- IRISSE (EA 4075), UFR SHE, University of La Réunion, 117 Rue du Général Ailleret, 97430, Le Tampon, France.
| | - Nathan Caron
- IRISSE (EA 4075), UFR SHE, University of La Réunion, 117 Rue du Général Ailleret, 97430, Le Tampon, France
| | - Nicolas A Turpin
- IRISSE (EA 4075), UFR SHE, University of La Réunion, 117 Rue du Général Ailleret, 97430, Le Tampon, France
| | - Georges Dalleau
- IRISSE (EA 4075), UFR SHE, University of La Réunion, 117 Rue du Général Ailleret, 97430, Le Tampon, France
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A noninvasive test for estimating myosin heavy chain of the vastus lateralis in females with mechanomyography. Med Eng Phys 2023; 111:103946. [PMID: 36792240 DOI: 10.1016/j.medengphy.2022.103946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 11/30/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
This study examined relationships between percent myosin heavy chain (%MHC) expression and mechanomyographic amplitude (MMGRMS). Fifteen females (age ± SD=21.3 ± 5.3 yrs) completed isometric trapezoidal contractions at 30% and 70% maximal voluntary contraction (MVC). MMG was recorded from the vastus lateralis (VL). Participants gave a muscle biopsy of the VL post-testing. MMGRMS-torque relationships during the linearly varying segments were log-transformed and linear regressions were applied to calculate b terms (slopes). For the steady torque segment, MMGRMS was averaged. Correlations were performed for type I%MHC with the MMG variables. Multiple regression was utilized to examine prediction equations for type I%MHC. Type I%MHC was significantly correlated with the b terms during the increasing segment of the 70% MVC (p = 0.003; r = -0.718), and MMGRMS during steady torque at 30% (p = 0.008; r = -0.652) and 70% MVC (p = 0.040; r = -0.535). Type I%MHC reduced the linearity of the MMGRMS-torque relationship during the high-intensity linearly increasing segment, and MMGRMS at a low- and high-intensity steady torque. A combination of MMG variables estimated type I%MHC expression with 81.2% accuracy. MMG recorded during a low- and high-intensity isometric trapezoidal contraction may offer a simple, noninvasive test for estimating type I%MHC expression of the VL in sedentary females.
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Hypoglycaemic therapy in frail older people with type 2 diabetes mellitus-a choice determined by metabolic phenotype. Aging Clin Exp Res 2022; 34:1949-1967. [PMID: 35723859 PMCID: PMC9208348 DOI: 10.1007/s40520-022-02142-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 04/21/2022] [Indexed: 11/01/2022]
Abstract
Frailty is a newly emerging complication of diabetes in older people and increasingly recognised in national and international clinical guidelines. However, frailty remains less clearly defined and frail older people with diabetes are rarely characterised. The general recommendation of clinical guidelines is to aim for a relaxed glycaemic control, mainly to avoid hypoglycaemia, in this often-vulnerable group of patients. With increasing age and development of frailty, body composition changes are characterised by an increase in visceral adipose tissue and a decrease in body muscle mass. Depending on the overall body weight, differential loss of muscle fibre types and body adipose/muscle tissue ratio, the presence of any associated frailty can be seen as a spectrum of metabolic phenotypes that vary in insulin resistance of which we have defined two specific phenotypes. The sarcopenic obese (SO) frail phenotype with increased visceral fat and increased insulin resistance on one side of spectrum and the anorexic malnourished (AM) frail phenotype with significant muscle loss and reduced insulin resistance on the other. In view of these varying metabolic phenotypes, the choice of hypoglycaemic therapy, glycaemic targets and overall goals of therapy are likely to be different. In the SO phenotype, weight-limiting hypoglycaemic agents, especially the new agents of GLP-1RA and SGLT-2 inhibitors, should be considered early on in therapy due to their benefits on weight reduction and ability to achieve tight glycaemic control where the focus will be on the reduction of cardiovascular risk. In the AM phenotype, weight-neutral agents or insulin therapy should be considered early on due to their benefits of limiting further weight loss and the possible anabolic effects of insulin. Here, the goals of therapy will be a combination of relaxed glycaemic control and avoidance of hypoglycaemia; and the focus will be on maintenance of a good quality of life. Future research is still required to develop novel hypoglycaemic agents with a positive effect on body composition in frailty and improvements in clinical outcomes.
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Abdelhafiz AH, Sinclair AJ. Metabolic phenotypes explain the relationship between dysglycaemia and frailty in older people with type 2 diabetes. J Diabetes Complications 2022; 36:108144. [PMID: 35151546 DOI: 10.1016/j.jdiacomp.2022.108144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 01/17/2022] [Accepted: 01/29/2022] [Indexed: 12/25/2022]
Abstract
BACKGROUND Dysglycaemia (hyperglycaemia and hypoglycaemia) increase the risk of frailty in older people with diabetes, which appears contradictory. However, the characteristics of patients included in these studies are different and may reflect different metabolic phenotypes of frailty that may explain this apparent contradiction. AIMS To review the characteristics of frail patients included in clinical studies that reported an association between dysglycaemia and frailty in order to explore whether there is any metabolic differences in the profile of these patients. METHODS A systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. Key words around older people, type 2 diabetes mellitus, frailty, hyperglycaemia and low glycaemia were used in the literature search. RESULTS Only 8 studies met the inclusion criteria. Four studies investigated the risk of frailty associated with low glycaemia. Two studies showed that hypoglycaemia increased the risk of frailty by 44% (HR 1.60, 95% CI 1.14 to 2.42) and predicted greater level of dependency (p < 0.001), respectively. The other two studies reported that HbA1c inversely correlated with clinical frailty scale (r = -0.31, p < 0.01) and HbA1c < 6.0% was associated with increased risk of disability (3.45, 1.02 to 11.6), respectively. Compared with non-frail patients, those with frailty tended to have lower body weight or body mass index (BMI), have features of malnutrition such as low serum albumin or low total cholesterol and suffer from more comorbidities including dementia. Four studies explored the association of high glycaemia with frailty. Higher HbA1c predicted frailty (OR 1.43, 95% CI 1.045 to 1.97) and positively correlated with Edmonton frail score (r = 0.44, p < 0.001), respectively in two studies. The other two studies found that subjects with HbA1c ≥ 6.5% had the greatest prevalence of frailty (70.3%) and subjects with higher HbA1c at baseline to have a higher frailty level throughout later life, respectively. Compared with non-frail patients, those with frailty tended to have higher body weight, waist circumference and BMI. They also have less physical activity, higher cholesterol level and have more comorbidities. CONCLUSIONS Dysglycaemia increases the risk of frailty but the characteristics of patients in these studies suggest different metabolic phenotypes of frailty. Therefore, these metabolic differences in frailty should be taken into consideration in the management of older people with diabetes.
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Affiliation(s)
- A H Abdelhafiz
- Department of Geriatric Medicine, Rotherham General Hospital, Moorgate Road, Rotherham S60 2UD, UK
| | - A J Sinclair
- King's College, London, UK; Foundation for Diabetes Research in Older People (fDROP), Droitwich Spa WR9 0QH, UK.
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Abdelhafiz AH, Pennells D, Sinclair AJ. A modern approach to glucose-lowering therapy in frail older people with type 2 diabetes mellitus. Expert Rev Endocrinol Metab 2022; 17:95-98. [PMID: 35209779 DOI: 10.1080/17446651.2022.2044304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 02/16/2022] [Indexed: 10/19/2022]
Affiliation(s)
- Ahmed H Abdelhafiz
- Department of Geriatric Medicine, Rotherham General Hospital, Rotherham, UK
| | - Daniel Pennells
- Department of Geriatric Medicine, Rotherham General Hospital, Rotherham, UK
| | - Alan J Sinclair
- King's College, London, UK
- Foundation for Diabetes Research in Older People (fDROP), Droitwich Spa, UK
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Gilloteaux J, Nicaise C, Sprimont L, Bissler J, Finkelstein JA, Payne WR. Leptin receptor defect with diabetes causes skeletal muscle atrophy in female obese Zucker rats where peculiar depots networked with mitochondrial damages. Ultrastruct Pathol 2021; 45:346-375. [PMID: 34743665 DOI: 10.1080/01913123.2021.1983099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Tibialis anterior muscles of 45-week-old female obese Zucker rats with defective leptin receptor and non-insulin dependent diabetes mellitus (NIDDM) showed a significative atrophy compared to lean muscles, based on histochemical-stained section's measurements in the sequence: oxidative slow twitch (SO, type I) < oxidative fast twitch (FOG, type IIa) < fast glycolytic (FG, type IIb). Both oxidative fiber's outskirts resembled 'ragged' fibers and, in these zones, ultrastructure revealed small clusters of endoplasm-like reticulum filled with unidentified electron contrasted compounds, contiguous and continuous with adjacent mitochondria envelope. The linings appeared crenated stabbed by circular patterns resembling those found of ceramides. The same fibers contained scattered degraded mitochondria that tethered electron contrasted droplets favoring larger depots while mitoptosis were widespread in FG fibers. Based on other interdisciplinary investigations on the lipid depots of diabetes 2 muscles made us to propose these accumulated contrasted contents to be made of peculiar lipids, including acyl-ceramides, as those were only found while diabetes 2 progresses in aging obese rats. These could interfere in NIDDM with mitochondrial oxidative energetic demands and muscle functions.
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Affiliation(s)
- Jacques Gilloteaux
- Department of Anatomical Sciences, St George's University School of Medicine, K B Taylor Global Scholar's Program at the University of Northumbria, School of Health and Life Sciences, Newcastle upon Tyne, UK.,Unité de Recherches de Physiologie Moleculaire (URPHyM) - Narilis, Département de Médecine, Université de Namur, Namur, Belgium.,Department of Anatomy, Northeast Ohio Medical University (Neomed), Rootstown, OH, USA
| | - Charles Nicaise
- Unité de Recherches de Physiologie Moleculaire (URPHyM) - Narilis, Département de Médecine, Université de Namur, Namur, Belgium
| | - Lindsay Sprimont
- Unité de Recherches de Physiologie Moleculaire (URPHyM) - Narilis, Département de Médecine, Université de Namur, Namur, Belgium
| | - John Bissler
- Department of Anatomy, Northeast Ohio Medical University (Neomed), Rootstown, OH, USA.,Division of Nephrology at St. Jude Children's Research Hospital and Le Bonheur Children's Hospital, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Judith A Finkelstein
- Department of Anatomy, Northeast Ohio Medical University (Neomed), Rootstown, OH, USA
| | - Warren R Payne
- Institute for Sport and Health, Footscray Park Campus, Victoria University, Melbourne, VIC, Australia
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Kim AK, Kwon DW, Yeom E, Lee KP, Kwon KS, Yu K, Lee KS. Lipophorin receptor 1 (LpR1) in Drosophila muscle influences life span by regulating mitochondrial aging. Biochem Biophys Res Commun 2021; 568:95-102. [PMID: 34217014 DOI: 10.1016/j.bbrc.2021.06.080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 06/24/2021] [Indexed: 10/21/2022]
Abstract
Sarcopenia is a syndrome characterized by progressive loss of muscle mass and function during aging. Although mitochondrial dysfunction and related metabolic defects precede age-related changes in muscle, their contributions to muscle aging are still not well known. In this study, we used a Drosophila model to investigate the role of lipophorin receptors (LpRs), a Drosophila homologue of the mammalian very low-density lipoprotein receptor (VLDLR), in mitochondrial dynamics and muscle aging. Muscle-specific knockdown of LpR1 or LpR2 resulted in mitochondrial dysfunction and reduced proteostasis, which contributed to muscle aging. Activation of AMP-activated protein kinase (AMPK) ameliorated muscle dysfunction induced by LpR1 knockdown. These results suggest that LpR1/VLDLR is a novel key target that modulates age-dependent lipid remodeling and muscle homeostasis.
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Affiliation(s)
- Ae-Kyeong Kim
- Metabolism and Neurophysiology Research Group, KRIBB, Daejeon, 34141, South Korea
| | - Dae-Woo Kwon
- Metabolism and Neurophysiology Research Group, KRIBB, Daejeon, 34141, South Korea; Department of Functional Genomics, UST, Daejeon, 34113, South Korea
| | - Eunbyul Yeom
- Metabolism and Neurophysiology Research Group, KRIBB, Daejeon, 34141, South Korea; Tunneling Nanotube Research Cnter, Korea University, Seoul, 02841, South Korea
| | - Kwang-Pyo Lee
- Department of Functional Genomics, UST, Daejeon, 34113, South Korea; Aging Research Center, KRIBB, Daejeon, 34141, South Korea; Aventi Inc. Daejeon, 34141, South Korea
| | - Ki-Sun Kwon
- Department of Functional Genomics, UST, Daejeon, 34113, South Korea; Aging Research Center, KRIBB, Daejeon, 34141, South Korea; Aventi Inc. Daejeon, 34141, South Korea
| | - Kweon Yu
- Metabolism and Neurophysiology Research Group, KRIBB, Daejeon, 34141, South Korea; Department of Functional Genomics, UST, Daejeon, 34113, South Korea; Convergence Research Center of Dementia, KIST, Seoul, 02792, South Korea.
| | - Kyu-Sun Lee
- Metabolism and Neurophysiology Research Group, KRIBB, Daejeon, 34141, South Korea; Department of Functional Genomics, UST, Daejeon, 34113, South Korea.
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Abdelhafiz AH, Emmerton D, Sinclair AJ. Impact of frailty metabolic phenotypes on the management of older people with type 2 diabetes mellitus. Geriatr Gerontol Int 2021; 21:614-622. [PMID: 34151494 DOI: 10.1111/ggi.14214] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/08/2021] [Accepted: 05/27/2021] [Indexed: 12/25/2022]
Abstract
AIMS To provide a pathophysiological basis for distinguishing metabolic variants of the frailty phenotype in older adults with type 2 diabetes. METHODS We have made an in-depth review of the possible mechanisms in diabetes, ageing and frailty that will alter allow us to describe phenotypic changes which might assist in predicting responses to particular glucose-lowering therapy. RESULTS Our review has enable us to describe with some confidence a sarcopenic obese phenotype and an anorexic malnourished phenotype. CONCLUSIONS By identifying these two phenotypes we can predict which would be most responsive to certain classes of therapy and where therapies may be ill-advised. This represents the first novel approach in this area. Further work is being planned to develop this hypothesis. Geriatr Gerontol Int 2021; 21: 614-622.
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Affiliation(s)
- Ahmed H Abdelhafiz
- Department of Geriatric Medicine, Rotherham General Hospital, Rotherham, UK
| | - Demelza Emmerton
- Department of Geriatric Medicine, Rotherham General Hospital, Rotherham, UK
| | - Alan J Sinclair
- Foundation for Diabetes Research in Older People, Diabetes Frail Ltd, Droitwich Spa, UK
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Jorgenson KW, Phillips SM, Hornberger TA. Identifying the Structural Adaptations that Drive the Mechanical Load-Induced Growth of Skeletal Muscle: A Scoping Review. Cells 2020; 9:cells9071658. [PMID: 32660165 PMCID: PMC7408414 DOI: 10.3390/cells9071658] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 12/21/2022] Open
Abstract
The maintenance of skeletal muscle mass plays a critical role in health and quality of life. One of the most potent regulators of skeletal muscle mass is mechanical loading, and numerous studies have led to a reasonably clear understanding of the macroscopic and microscopic changes that occur when the mechanical environment is altered. For instance, an increase in mechanical loading induces a growth response that is mediated, at least in part, by an increase in the cross-sectional area of the myofibers (i.e., myofiber hypertrophy). However, very little is known about the ultrastructural adaptations that drive this response. Even the most basic questions, such as whether mechanical load-induced myofiber hypertrophy is mediated by an increase in the size of the pre-existing myofibrils and/or an increase in the number myofibrils, have not been resolved. In this review, we thoroughly summarize what is currently known about the macroscopic, microscopic and ultrastructural changes that drive mechanical load-induced growth and highlight the critical gaps in knowledge that need to be filled.
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Affiliation(s)
- Kent W. Jorgenson
- School of Veterinary Medicine and the Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, USA;
| | - Stuart M. Phillips
- Department of Kinesiology, McMaster University, Hamilton, ON L8S 4K1, Canada;
| | - Troy A. Hornberger
- School of Veterinary Medicine and the Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, USA;
- Correspondence:
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15
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Ravn MK, Ostergaard TI, Schroeder HD, Nyengaard JR, Lambertsen KL, Frich LH. Supraspinatus and deltoid muscle fiber composition in rotator cuff tear conditions. JSES Int 2020; 4:431-437. [PMID: 32939464 PMCID: PMC7479021 DOI: 10.1016/j.jseint.2020.04.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Background Rotator cuff (RC) tears are associated with RC muscle atrophy and changes in composition that are crucial to the prognosis of RC repair. The aim of this study was to characterize muscle fiber composition in the supraspinatus (SS) muscle under tear conditions. Methods Muscle biopsies were obtained from 21 patients undergoing surgery for an RC tendon tear. Biopsies were obtained from the musculotendinous junction of the SS muscle, and control biopsies were harvested from the deltoid muscle (DT). Biopsies were immunohistochemically processed for detection of type 1 (slow type) and type 2 (fast type) fibers and analyzed using unbiased, stereological principles. We counted the total numbers of type 1 and 2 muscle fibers/mm2, and fiber diameter was used to estimate muscle fiber atrophy and hypertrophy. Results We found significantly more type 2 cells/mm2 in the SS compared with the DT (P < .01). In addition, we found a significantly higher fraction of type 1 fibers than type 2 fibers in the DT (P < .01), whereas both fiber types were equally present in the SS. The diameters of SS cells were generally smaller than those of DT cells. Atrophy of especially SS type 2 fibers was also demonstrated. Fiber atrophy was more pronounced in men than women. Conclusion The changes in the composition of SS muscle cell types suggest a shift from type 1 to type 2 muscle fibers and atrophy of both type 1 and 2 fibers. This composition indicates loss of endurance and rapid fatigue of the SS muscle under RC tear conditions.
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Affiliation(s)
- Morten Kjaer Ravn
- Department of Orthopaedics, Odense University Hospital, Odense, Denmark.,The Orthopaedic Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Trine Ivarsen Ostergaard
- Department of Orthopaedics, Odense University Hospital, Odense, Denmark.,The Orthopaedic Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | | | - Jens Randel Nyengaard
- Department of Clinical Medicine - Core Centre for Molecular Morphology, Section for Stereology and Microscopy, Center for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark
| | - Kate Lykke Lambertsen
- Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Neurology, Odense University Hospital, Odense, Denmark.,BRIDGE - Brain Research - Inter-Disciplinary Guided Excellence, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Lars Henrik Frich
- Department of Orthopaedics, Odense University Hospital, Odense, Denmark.,The Orthopaedic Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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16
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Medler S. Mixing it up: the biological significance of hybrid skeletal muscle fibers. ACTA ACUST UNITED AC 2019; 222:222/23/jeb200832. [PMID: 31784473 DOI: 10.1242/jeb.200832] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Skeletal muscle fibers are classified according to the myosin heavy chain (MHC) isoforms and other myofibrillar proteins expressed within these cells. In addition to 'pure' fibers expressing single MHC isoforms, many fibers are 'hybrids' that co-express two or more different isoforms of MHC or other myofibrillar proteins. Although hybrid fibers have been recognized by muscle biologists for more than three decades, uncertainty persists about their prevalence in normal muscles, their role in fiber-type transitions, and what they might tell us about fiber-type regulation at the cellular and molecular levels. This Review summarizes current knowledge on the relative abundance of hybrid fibers in a variety of muscles from different species. Data from more than 150 muscles from 39 species demonstrate that hybrid fibers are common, frequently representing 25% or more of the fibers in normal muscles. Hybrid fibers appear to have two main roles: (1) they function as intermediates during the fiber-type transitions associated with skeletal muscle development, adaptation to exercise and aging; and (2) they provide a functional continuum of fiber phenotypes, as they possess physiological properties that are intermediate to those of pure fiber types. One aspect of hybrid fibers that is not widely recognized is that fiber-type asymmetries - such as dramatic differences in the MHC composition along the length of single fibers - appear to be a common aspect of many fibers. The final section of this Review examines the possible role of differential activities of nuclei in different myonuclear domains in establishing fiber-type asymmetries.
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Affiliation(s)
- Scott Medler
- Biology Department, State University of New York at Fredonia, Fredonia, NY 14063, USA
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17
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Blackburn DM, Lazure F, Corchado AH, Perkins TJ, Najafabadi HS, Soleimani VD. High-resolution genome-wide expression analysis of single myofibers using SMART-Seq. J Biol Chem 2019; 294:20097-20108. [PMID: 31753917 DOI: 10.1074/jbc.ra119.011506] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/15/2019] [Indexed: 12/26/2022] Open
Abstract
Skeletal muscle is a heterogeneous tissue. Individual myofibers that make up muscle tissue exhibit variation in their metabolic and contractile properties. Although biochemical and histological assays are available to study myofiber heterogeneity, efficient methods to analyze the whole transcriptome of individual myofibers are lacking. Here, we report on a single-myofiber RNA-sequencing (smfRNA-Seq) approach to analyze the whole transcriptome of individual myofibers by combining single-fiber isolation with Switching Mechanism at 5' end of RNA Template (SMART) technology. Using smfRNA-Seq, we first determined the genes that are expressed in the whole muscle, including in nonmyogenic cells. We also analyzed the differences in the transcriptome of myofibers from young and old mice to validate the effectiveness of this new method. Our results suggest that aging leads to significant changes in the expression of metabolic genes, such as Nos1, and structural genes, such as Myl1, in myofibers. We conclude that smfRNA-Seq is a powerful tool to study developmental, disease-related, and age-related changes in the gene expression profile of skeletal muscle.
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Affiliation(s)
- Darren M Blackburn
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada.,Molecular and Regenerative Medicine Axis, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Felicia Lazure
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada.,Molecular and Regenerative Medicine Axis, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Aldo H Corchado
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada
| | - Theodore J Perkins
- Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario K1H 8L6, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Hamed S Najafabadi
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada
| | - Vahab D Soleimani
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada .,Molecular and Regenerative Medicine Axis, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
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18
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Bontemps B, Piponnier E, Chalchat E, Blazevich AJ, Julian V, Bocock O, Duclos M, Martin V, Ratel S. Children Exhibit a More Comparable Neuromuscular Fatigue Profile to Endurance Athletes Than Untrained Adults. Front Physiol 2019; 10:119. [PMID: 30828304 PMCID: PMC6384268 DOI: 10.3389/fphys.2019.00119] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/30/2019] [Indexed: 11/13/2022] Open
Abstract
The present study compared neuromuscular fatigue profiles between children, untrained adults and adult endurance athletes during repeated maximal muscle contractions. Eighteen prepubertal boys, 19 untrained men and 13 endurance male athletes performed 5-s maximal voluntary isometric knee extensor contractions (MVICs) interspersed with 5-s recovery until MVIC reached 60% of its initial value. Single and doublet magnetic stimulations were delivered to the femoral nerve to quantify the time course of potentiated twitch amplitude (Ttw,pot), high-frequency torque (T100 Hz) and the low-to-high frequency torque ratio (T10 Hz/T100 Hz), i.e., indicators of peripheral fatigue. M-wave-normalized EMG amplitudes (EMG/M) and the maximal voluntary activation level (VA) were calculated to quantify central fatigue. Adults (15.9 ± 3.9 repetitions) performed fewer MVICs than children (40.4 ± 19.7) and endurance athletes (51.7 ± 19.6), however, no difference was observed between children and athletes (P = 0.13). Ttw,pot (∼52%, P < 0.001), T100 Hz (∼39%, P < 0.001) and T10 Hz/T100 Hz (∼23%, P < 0.001) decreased only in adults. Similar decrements in vastus medialis and vastus lateralis EMG/M were observed in children and endurance athletes (range: 40-50%), and these were greater than in adults (∼15%). Whilst VA decreased more in children (-38.4 ± 22.5%, P < 0.001) than endurance athletes (-20.3 ± 10.1%, P < 0.001), it did not change in adults. Thus, children fatigued more slowly than adults and as much as endurance athletes. They developed less peripheral and more central fatigue than adults and, although central fatigue appeared somewhat higher in children than endurance athletes, both children and endurance athletes experienced greater decrements than adults. Therefore, children exhibit a more comparable neuromuscular fatigue profile to endurance athletes than adults.
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Affiliation(s)
| | - Enzo Piponnier
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, France
| | - Emeric Chalchat
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, France
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Valérie Julian
- Clermont-Ferrand University Hospital, Clermont-Ferrand, France
| | - Olivia Bocock
- Clermont-Ferrand University Hospital, Clermont-Ferrand, France
| | - Martine Duclos
- Clermont-Ferrand University Hospital, Clermont-Ferrand, France
| | - Vincent Martin
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, France
| | - Sébastien Ratel
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, France
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19
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Franzini-Armstrong C. The relationship between form and function throughout the history of excitation-contraction coupling. J Gen Physiol 2018; 150:189-210. [PMID: 29317466 PMCID: PMC5806676 DOI: 10.1085/jgp.201711889] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Franzini-Armstrong reviews the development of the excitation–contraction coupling field over time. The concept of excitation–contraction coupling is almost as old as Journal of General Physiology. It was understood as early as the 1940s that a series of stereotyped events is responsible for the rapid contraction response of muscle fibers to an initial electrical event at the surface. These early developments, now lost in what seems to be the far past for most young investigators, have provided an endless source of experimental approaches. In this Milestone in Physiology, I describe in detail the experiments and concepts that introduced and established the field of excitation–contraction coupling in skeletal muscle. More recent advances are presented in an abbreviated form, as readers are likely to be familiar with recent work in the field.
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Affiliation(s)
- Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA
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20
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Capitanio D, Moriggi M, Gelfi C. Mapping the human skeletal muscle proteome: progress and potential. Expert Rev Proteomics 2017; 14:825-839. [PMID: 28780899 DOI: 10.1080/14789450.2017.1364996] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Human skeletal muscle represents 40% of our body mass and deciphering its proteome composition to further understand mechanisms regulating muscle function under physiological and pathological conditions has proved a challenge. The inter-individual variability, the presence of structurally and functionally different muscle types and the high protein dynamic range require carefully selected methodologies for the assessment of the muscle proteome. Furthermore, physiological studies are understandingly hampered by ethical issues related to biopsies on healthy subjects, making it difficult to recruit matched controls essential for comparative studies. Areas covered: This review critically analyses studies performed on muscle to date and identifies what still remains unknown or poorly investigated in physiological and pathological states, such as training, aging, metabolic disorders and muscular dystrophies. Expert commentary: Efforts should be made on biological fluid analyses targeting low abundant/low molecular weight fragments generated from muscle cell disruption to improve diagnosis and clinical monitoring. From a methodological point of view, particular attention should be paid to improve the characterization of intact proteins and unknown post translational modifications to better understand the molecular mechanisms of muscle disorders.
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Affiliation(s)
- Daniele Capitanio
- a Department of Biomedical Sciences for Health , University of Milan , Segrate , Milan , Italy
| | - Manuela Moriggi
- a Department of Biomedical Sciences for Health , University of Milan , Segrate , Milan , Italy
| | - Cecilia Gelfi
- a Department of Biomedical Sciences for Health , University of Milan , Segrate , Milan , Italy
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21
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Koh ES, Kim HC, Lim JY. The effects of electromyostimulation application timing on denervated skeletal muscle atrophy. Muscle Nerve 2017; 56:E154-E161. [PMID: 28345221 DOI: 10.1002/mus.25656] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 03/06/2017] [Accepted: 03/20/2017] [Indexed: 12/25/2022]
Abstract
INTRODUCTION In this study we evaluated the effect of electromyostimulation (EMS) on myosin heavy chain (MHC) isoform expression in denervated rat muscles to determine the optimal timing for EMS application. METHODS EMS was initiated on post-injury day 1 for the group with denervation receiving immediate EMS (DIEMS) and on post-injury day 15 for the group with denervation receiving delayed EMS (DDEMS) in rat denervated muscles. Muscle wet weight and muscle fiber cross-sectional area (FCSA) were measured. MHC isoforms were analyzed in both protein homogenates and single muscle fibers. RESULTS The expression levels of IIx and IIb isoforms of MHC were significantly lower and higher, respectively, in the gastrocnemius muscles of the DIEMS group, but not the DDEMS group. The DIEMS group also showed larger FCSA and a lower proportion of hybrid single fibers compared with the DDEMS group. DISCUSSION These results indicate that immediate EMS is more effective than delayed EMS for aiding recovery of denervation-induced MHC changes. Muscle Nerve 56: E154-E161, 2017.
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Affiliation(s)
- Eun Sil Koh
- Department of Rehabilitation Medicine, National Medical Center, Seoul, Republic of Korea.,Department of Biomedical Engineering, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hee Chan Kim
- Department of Biomedical Engineering, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jae-Young Lim
- Mechanic & Molecular Myology Laboratory, Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, 173-82, Gumi-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea
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22
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Trevino MA, Herda TJ, Fry AC, Gallagher PM, Vardiman JP, Mosier EM, Miller JD. Influence of the contractile properties of muscle on motor unit firing rates during a moderate-intensity contraction in vivo. J Neurophysiol 2016; 116:552-62. [PMID: 27146989 PMCID: PMC4978784 DOI: 10.1152/jn.01021.2015] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 05/02/2016] [Indexed: 11/22/2022] Open
Abstract
It is suggested that firing rate characteristics of motor units (MUs) are influenced by the physical properties of the muscle. However, no study has correlated MU firing rates at recruitment, targeted force, or derecruitment with the contractile properties of the muscle in vivo. Twelve participants (age = 20.67 ± 2.35 yr) performed a 40% isometric maximal voluntary contraction of the leg extensors that included linearly increasing, steady force, and decreasing segments. Muscle biopsies were collected with myosin heavy chain (MHC) content quantified, and surface electromyography (EMG) was recorded from the vastus lateralis. The EMG signal was decomposed into the firing events of single MUs. Slopes and y-intercepts were calculated for 1) firing rates at recruitment vs. recruitment threshold, 2) mean firing rates at steady force vs. recruitment threshold, and 3) firing rates at derecruitment vs. derecruitment threshold relationships for each subject. Correlations among type I %MHC isoform content and the slopes and y-intercepts from the three relationships were examined. Type I %MHC isoform content was correlated with MU firing rates at recruitment (y-intercepts: r = -0.577; slopes: r = 0.741) and targeted force (slopes: r = 0.853) vs. recruitment threshold and MU firing rates at derecruitment (y-intercept: r = -0.597; slopes: r = 0.701) vs. derecruitment threshold relationships. However, the majority of the individual MU firing rates vs. recruitment and derecruitment relationships were not significant (P > 0.05) and, thus, revealed no systematic pattern. In contrast, MU firing rates during the steady force demonstrated a systematic pattern with higher firing rates for the lower- than higher-threshold MUs and were correlated with the physical properties of MUs in vivo.
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Affiliation(s)
| | - Trent J Herda
- Neuromechanics Laboratory, University of Kansas, Lawrence, Kansas;
| | - Andrew C Fry
- Applied Physiology Laboratory, University of Kansas, Lawrence, Kansas; and
| | - Philip M Gallagher
- Applied Physiology Laboratory, University of Kansas, Lawrence, Kansas; and
| | - John P Vardiman
- Applied Physiology and Sports Medicine Laboratory, Kansas State University, Manhattan, Kansas
| | - Eric M Mosier
- Neuromechanics Laboratory, University of Kansas, Lawrence, Kansas
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23
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Dowling P, Murphy S, Ohlendieck K. Proteomic profiling of muscle fibre type shifting in neuromuscular diseases. Expert Rev Proteomics 2016; 13:783-99. [DOI: 10.1080/14789450.2016.1209416] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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24
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Stutzig N, Rzanny R, Moll K, Gussew A, Reichenbach JR, Siebert T. The pH heterogeneity in human calf muscle during neuromuscular electrical stimulation. Magn Reson Med 2016; 77:2097-2106. [PMID: 27436629 DOI: 10.1002/mrm.26329] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/02/2016] [Accepted: 06/12/2016] [Indexed: 12/30/2022]
Abstract
PURPOSE The aim of the study was to examine pH heterogeneity during fatigue induced by neuromuscular electrical stimulation (NMES) using phosphorus magnetic resonance spectroscopy (31 P-MRS). It is hypothesized that three pH components would occur in the 31 P-MRS during fatigue, representing three fiber types. METHODS The medial gastrocnemius of eight subjects was stimulated within a 3-Tesla whole body MRI scanner. The maximal force during stimulation (Fstim ) was examined by a pressure sensor. Phosphocreatine (PCr), adenosintriphosphate, inorganic phosphate (Pi), and the corresponding pH were estimated by a nonvolume-selective 31 P-MRS using a small loop coil at rest and during fatigue. RESULTS During fatigue, Fstim and PCr decreased to 27% and 33% of their initial levels, respectively. In all cases, the Pi peak increased when NMES was started and split into three different peaks. Based on the single Pi peaks during fatigue, an alkaline (6.76 ± 0.08), a medium (6.40 ± 0.06), and an acidic (6.09 ± 0.05) pH component were observed compared to the pH (7.02 ± 0.02) at rest. CONCLUSION It is suggested that NMES is able to induce pH heterogeneity in the medial gastrocnemius, and that the single Pi peaks represent the different muscle fiber types of the skeletal muscle. Magn Reson Med 77:2097-2106, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Norman Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - Reinhard Rzanny
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Kevin Moll
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Alexander Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Tobias Siebert
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
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25
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Perkisas S, De Cock A, Verhoeven V, Vandewoude M. Physiological and architectural changes in the ageing muscle and their relation to strength and function in sarcopenia. Eur Geriatr Med 2016. [DOI: 10.1016/j.eurger.2015.12.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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26
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Li Y, Xu S, Zhang X, Yi Z, Cichello S. Skeletal intramyocellular lipid metabolism and insulin resistance. BIOPHYSICS REPORTS 2015; 1:90-98. [PMID: 26942223 PMCID: PMC4762133 DOI: 10.1007/s41048-015-0013-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/10/2015] [Indexed: 12/24/2022] Open
Abstract
Lipids stored in skeletal muscle cells are known as intramyocellular lipid (IMCL). Disorders involving IMCL and its causative factor, circulatory free fatty acids (FFAs), induce a toxic state and ultimately result in insulin resistance (IR) in muscle tissue. On the other hand, intramuscular triglyceride (IMTG), the most abundant component of IMCL and an essential energy source for active skeletal muscle, is different from other IMCLs, as it is stored in lipid droplets and plays a pivotal role in skeletal muscle energy homeostasis. This review discusses the association of FFA-induced ectopic lipid accumulation and IR, with specific emphasis on the relationship between IMCL/IMTG metabolism and IR.
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Affiliation(s)
- Yiran Li
- Department of Biological Science and Biotechnology, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191 China ; National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Shimeng Xu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China ; University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Xuelin Zhang
- Capital University of Physical Education and Sport, Beijing, 100191 China
| | - Zongchun Yi
- Department of Biological Science and Biotechnology, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191 China
| | - Simon Cichello
- School of Life Sciences, La Trobe University, Melbourne, VIC 3086 Australia
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27
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Trappe S, Luden N, Minchev K, Raue U, Jemiolo B, Trappe TA. Skeletal muscle signature of a champion sprint runner. J Appl Physiol (1985) 2015; 118:1460-6. [PMID: 25749440 DOI: 10.1152/japplphysiol.00037.2015] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/02/2015] [Indexed: 11/22/2022] Open
Abstract
We had the unique opportunity to study the skeletal muscle characteristics, at the single fiber level, of a world champion sprint runner who is the current indoor world record holder in the 60-m hurdles (7.30 s) and former world record holder in 110-m hurdles (12.91 s). Muscle biopsies were obtained from the vastus lateralis at rest and 4 h after a high-intensity exercise challenge (4 × 7 repetitions of resistance exercise). Single muscle fiber analyses were conducted for fiber type distribution (myosin heavy chain, MHC), fiber size, contractile function (strength, speed, and power) and mRNA expression (before and after the exercise bout). The world-class sprinter's leg muscle had a high abundance (24%) of the pure MHC IIx muscle fibers with a total fast-twitch fiber population of 71%. Power output of the MHC IIx fibers (35.1 ± 1.4 W/l) was 2-fold higher than MHC IIa fibers (17.1 ± 0.5 W/l) and 14-fold greater than MHC I fibers (2.5 ± 0.1 W/l). Additionally, the MHC IIx fibers were highly responsive to intense exercise at the transcriptional level for genes involved with muscle growth and remodeling (Fn14 and myostatin). To our knowledge, the abundance of pure MHC IIx muscle fibers is the highest observed in an elite sprinter. Further, the power output of the MHC IIa and MHC IIx muscle fibers was greater than any human values reported to date. These data provide a myocellular basis for the high level of sprinting success achieved by this individual.
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Affiliation(s)
- Scott Trappe
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Nicholas Luden
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Kiril Minchev
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Ulrika Raue
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Bozena Jemiolo
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Todd A Trappe
- Human Performance Laboratory, Ball State University, Muncie, Indiana
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28
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SOUKUP T, DIALLO M. Proportions of Myosin Heavy Chain mRNAs, Protein Isoforms and Fiber Types in the Slow and Fast Skeletal Muscles Are Maintained After Alterations of Thyroid Status in Rats. Physiol Res 2015; 64:111-8. [DOI: 10.33549/physiolres.932831] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Recently, we have established that slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles of euthyroid (EU) Lewis rats posses the same proportions between their four myosin heavy chain (MyHC) mRNAs, protein isoforms and fiber types as determined by real time RT-PCR, SDS-PAGE and 2-D stereological fiber type analysis, respectively. In the present paper we investigated if these proportions are maintained in adult Lewis rats with hyperthyroid (HT) and hypothyroid (HY) status. Although HT and HY states change MyHC isoform expression, results from all three methods showed that proportion between MyHC mRNA-1, ‑2a, -2x/d, -2b, protein isoforms MyHC-1, -2a, -2x/d, -2b and to lesser extent also fiber types 1, 2A, 2X/D, 2B were preserved in both SOL and EDL muscles. Furthermore, in the SOL muscle mRNA expression of slow MyHC-1 remained up to three orders higher compared to fast MyHC transcripts, which explains the predominance of MyHC-1 isoform and fiber type 1 even in HT rats. Although HT status led in the SOL to increased expression of MyHC-2a mRNA, MyHC-2a isoform and 2A fibers, it preserved extremely low expression of MyHC-2x and -2b mRNA and protein isoforms, which explains the absence of pure 2X/D and 2B fibers. HY status, on the other hand, almost completely abolished expression of all three fast MyHC mRNAs, MyHC protein isoforms and fast fiber types in the SOL muscle. Our data present evidence that a correlation between mRNA, protein content and fiber type composition found in EU status is also preserved in HT and HY rats.
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Affiliation(s)
- T. SOUKUP
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Allen MD, Kimpinski K, Doherty TJ, Rice CL. Decreased muscle endurance associated with diabetic neuropathy may be attributed partially to neuromuscular transmission failure. J Appl Physiol (1985) 2015; 118:1014-22. [PMID: 25663671 DOI: 10.1152/japplphysiol.00441.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 02/03/2015] [Indexed: 01/25/2023] Open
Abstract
Diabetic polyneuropathy (DPN) can cause muscle atrophy, weakness, contractile slowing, and neuromuscular transmission instability. Our objective was to assess the response of the impaired neuromuscular system of DPN in humans when stressed with a sustained maximal voluntary contraction (MVC). Baseline MVC and evoked dorsiflexor contractile properties were assessed in DPN patients (n = 10) and controls (n = 10). Surface electromyography was used to record tibialis anterior evoked maximal compound muscle action potentials (CMAPs) and neuromuscular activity during MVCs. Participants performed a sustained isometric dorsiflexion MVC for which task termination was determined by the inability to sustain ≥60% MVC torque. The fatigue protocol was immediately followed by a maximal twitch, with additional maximal twitches and MVCs assessed at 30 s and 2 min postfatigue. DPN patients fatigued ∼21% more quickly than controls (P < 0.05) and featured less relative electromyographic activity during the first one-third of the fatigue protocol compared with controls (P < 0.05). Immediately following fatigue, maximal twitch torque was reduced similarly (∼20%) in both groups, and concurrently CMAPs were reduced (∼12%) in DPN patients, whereas they were unaffected in controls (P > 0.05). Twitch torque and CMAP amplitude recovered to baseline 30 s postfatigue. Additionally, at 30 s postfatigue, both groups had similar (∼10%) reductions in MVC torque relative to baseline, and MVC strength recovered by 2 min postfatigue. We conclude DPN patients possess less endurance than controls, and neuromuscular transmission failure may contribute to this greater fatigability.
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Affiliation(s)
- Matti D Allen
- School of Medicine, Queen's University, Kingston, Ontario, Canada; School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada; School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada;
| | - Kurt Kimpinski
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Timothy J Doherty
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada; Department of Physical Medicine and Rehabilitation, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada; and
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
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Murgia M, Nagaraj N, Deshmukh AS, Zeiler M, Cancellara P, Moretti I, Reggiani C, Schiaffino S, Mann M. Single muscle fiber proteomics reveals unexpected mitochondrial specialization. EMBO Rep 2015; 16:387-95. [PMID: 25643707 PMCID: PMC4364878 DOI: 10.15252/embr.201439757] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mammalian skeletal muscles are composed of multinucleated cells termed slow or fast fibers according to their contractile and metabolic properties. Here, we developed a high-sensitivity workflow to characterize the proteome of single fibers. Analysis of segments of the same fiber by traditional and unbiased proteomics methods yielded the same subtype assignment. We discovered novel subtype-specific features, most prominently mitochondrial specialization of fiber types in substrate utilization. The fiber type-resolved proteomes can be applied to a variety of physiological and pathological conditions and illustrate the utility of single cell type analysis for dissecting proteomic heterogeneity.
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Affiliation(s)
- Marta Murgia
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Nagarjuna Nagaraj
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Atul S Deshmukh
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marlis Zeiler
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Pasqua Cancellara
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Irene Moretti
- Venetian Institute of Molecular Medicine, Padua, Italy
| | - Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | | | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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ŽURMANOVÁ J, SOUKUP T. Comparison of Myosin Heavy Chain mRNAs, Protein Isoforms and Fiber Type Proportions in the Rat Slow and Fast Muscles. Physiol Res 2013; 62:445-53. [DOI: 10.33549/physiolres.932418] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
We studied the expression of myosin heavy chain isoforms at mRNA and protein levels as well as fiber type composition in the fast extensor digitorum longus (EDL) and slow soleus (SOL) twitch muscles of adult inbred Lewis strain rats. Comparison of the results from Real Time RT-PCR, SDS-PAGE and fiber type analysis showed corresponding proportions of MyHC transcripts (MyHC-1, -2a, -2x/d, -2b), protein isoforms (MyHC-1, -2a, -2x/d, -2b) and fiber types (type 1, 2A, 2X/D, 2B) in both muscles. Furthermore, we found that slow MyHC-1 mRNA expression in the SOL was up to three orders higher than that of fast MyHC transcripts. This finding can explain the predominance of MyHC-1 isoform and fiber type 1 and the absence of pure 2X/D and 2B fibers in the SOL muscle. Based on our data presenting quantitative evidence of corresponding proportions between mRNA level, protein content and fiber type composition, we suggest that the Real Time RT-PCR technique can be used as a routine method for analysis of muscle composition changes and could be advantageous for the analysis of scant biological samples such as muscle biopsies in humans.
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Affiliation(s)
| | - T. SOUKUP
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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32
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Panissa VLG, Azevedo NRM, Julio UF, Andreato LV, Pinto E Silva CM, Hardt F, Franchini E. Maximum number of repetitions, total weight lifted and neuromuscular fatigue in individuals with different training backgrounds. Biol Sport 2013; 30:131-6. [PMID: 24744479 PMCID: PMC3944574 DOI: 10.5604/20831862.1044458] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2013] [Indexed: 11/15/2022] Open
Abstract
The aim of this study was to evaluate the performance, as well as neuromuscular activity, in a strength task in subjects with different training backgrounds. Participants (n = 26) were divided into three groups according to their training backgrounds (aerobic, strength or mixed) and submitted to three sessions: (1) determination of the maximum oxygen uptake during the incremental treadmill test to exhaustion and familiarization of the evaluation of maximum strength (1RM) for the half squat; (2) 1RM determination; and (3) strength exercise, four sets at 80% of the 1RM, in which the maximum number of repetitions (MNR), the total weight lifted (TWL), the root mean square (RMS) and median frequency (MF) of the electromyographic (EMG) activity for the second and last repetition were computed. There was an effect of group for MNR, with the aerobic group performing a higher MNR compared to the strength group (P = 0.045), and an effect on MF with a higher value in the second repetition than in the last repetition (P = 0.016). These results demonstrated that individuals with better aerobic fitness were more fatigue resistant than strength trained individuals. The absence of differences in EMG signals indicates that individuals with different training backgrounds have a similar pattern of motor unit recruitment during a resistance exercise performed until failure, and that the greater capacity to perform the MNR probably can be explained by peripheral adaptations.
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Affiliation(s)
- V L G Panissa
- School of Physical Education and Sport, University of São Paulo, Brazil
| | - Neto R M Azevedo
- School of Physical Education and Sport, University of São Paulo, Brazil
| | - U F Julio
- School of Physical Education and Sport, University of São Paulo, Brazil
| | - L V Andreato
- School of Physical Education and Sport, University of São Paulo, Brazil
| | - C M Pinto E Silva
- School of Physical Education and Sport, University of São Paulo, Brazil
| | - F Hardt
- School of Physical Education and Sport, University of São Paulo, Brazil
| | - E Franchini
- School of Physical Education and Sport, University of São Paulo, Brazil
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Hazimihalis P, Gorvet M, Butcher M. Myosin Isoform Fiber Type and Fiber Size in the Tail of the Virginia Opossum (Didelphis virginiana). Anat Rec (Hoboken) 2012; 296:96-107. [DOI: 10.1002/ar.22614] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 05/29/2012] [Accepted: 08/17/2012] [Indexed: 11/09/2022]
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Feng X, Zhang T, Xu Z, Choi SJ, Qian J, Furdui CM, Register TC, Delbono O. Myosin heavy chain isoform expression in the Vastus Lateralis muscle of aging African green vervet monkeys. Exp Gerontol 2012; 47:601-7. [PMID: 22617406 DOI: 10.1016/j.exger.2012.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 04/07/2012] [Accepted: 05/08/2012] [Indexed: 10/28/2022]
Abstract
Non-human primates (NHP) represent an emerging animal model for the study of physical function, and provide opportunities for exploration of relationships of muscle biomolecular changes with age. One such primate model, the African green vervet monkey, has been used extensively in biomedical research but little is known regarding skeletal muscle composition, expression of myosin heavy chain (MHC) isoforms, and changes with age. In the present study we examined the effects of age on vastus lateralis (VL) muscle fiber-type composition, fiber cross-sectional area (CSA), and MHC isoforms expressed in 4 young and 4 older adult vervet monkeys. Proteomics analysis, using a human and nonhuman primate protein database, showed five MHC isoforms (I, IIA, IIX, IIB, and IIB') expressed in female vervet VL muscle, which matched the human MHC isoforms. Fast type II fibers predominated and no pure type IIB or IIB' containing fibers were detected. Hybrid fibers containing IIB/IIB' MHC decreased in the old vervets. The CSA of both type I and type II fibers was significantly smaller in older vervet while type IIA fibers showed the most severity of atrophy. The decrease of fast MHC and atrophy of muscle fiber with aging recapitulate observations in human VL muscle. These findings, along with its homology of MHC between the vervet and human suggested that the vervet monkey may be a suitable preclinical model for understanding the cellular and molecular basis of sarcopenia and for developing new interventions to ameliorate the impact of disorders that affect skeletal muscle structure and function.
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Affiliation(s)
- Xin Feng
- Department of Otolaryngology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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Abstract
Muscle plasticity is defined as the ability of a given muscle to alter its structural and functional properties in accordance with the environmental conditions imposed on it. As such, respiratory muscle is in a constant state of remodeling, and the basis of muscle's plasticity is its ability to change protein expression and resultant protein balance in response to varying environmental conditions. Here, we will describe the changes of respiratory muscle imposed by extrinsic changes in mechanical load, activity, and innervation. Although there is a large body of literature on the structural and functional plasticity of respiratory muscles, we are only beginning to understand the molecular-scale protein changes that contribute to protein balance. We will give an overview of key mechanisms regulating protein synthesis and protein degradation, as well as the complex interactions between them. We suggest future application of a systems biology approach that would develop a mathematical model of protein balance and greatly improve treatments in a variety of clinical settings related to maintaining both muscle mass and optimal contractile function of respiratory muscles.
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Affiliation(s)
- Heather M Gransee
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
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36
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Uzun S, Pourmoghaddam A, Hieronymus M, Thrasher TA. Evaluation of muscle fatigue of wheelchair basketball players with spinal cord injury using recurrence quantification analysis of surface EMG. Eur J Appl Physiol 2012; 112:3847-57. [PMID: 22395284 DOI: 10.1007/s00421-012-2358-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 02/14/2012] [Indexed: 11/26/2022]
Abstract
Wheelchair basketball is the most popular exercise activity among individuals with spinal cord injury (SCI). The purpose of this study was to investigate muscular endurance and fatigue in wheelchair basketball athletes with SCI using surface electromyography (SEMG) and maximal torque values. SEMG characteristics of 10 wheelchair basketball players (WBP) were compared to 13 able-bodied basketball players and 12 sedentary able-bodied subjects. Participants performed sustained isometric elbow flexion at 50% maximal voluntary contraction until exhaustion. Elbow flexion torque and SEMG signals were recorded from three elbow flexor muscles: biceps brachii longus, biceps brachii brevis and brachioradialis. SEMG signals were clustered into 0.5-s epochs with 50% overlap. Root mean square (RMS) and median frequency (MDF) of SEMG signals were calculated for each muscle and epoch as traditional fatigue monitoring. Recurrence quantification analysis was used to extract the percentage of determinism (%DET) of SEMG signals. The slope of the %DET for basketball players and WBP showed slower increase with time than the sedentary able-bodied control group for three different elbow flexor muscles, while no difference was observed for the slope of the %DET between basketball and WBP. This result indicated that the athletes are less fatigable during the task effort than the nonathletes. Normalized MDF slope decay exhibited similar results between the groups as %DET, while the slope of the normalized RMS failed to show any significant differences among the groups (p > 0.05). MDF and %DET could be useful for the evaluation of muscle fatigue in wheelchair basketball training. No conclusions about special training for WBP could be determined.
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Affiliation(s)
- S Uzun
- School of Physical Education and Sport, Marmara University, Istanbul, Turkey.
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Chemello F, Bean C, Cancellara P, Laveder P, Reggiani C, Lanfranchi G. Microgenomic analysis in skeletal muscle: expression signatures of individual fast and slow myofibers. PLoS One 2011; 6:e16807. [PMID: 21364935 PMCID: PMC3043066 DOI: 10.1371/journal.pone.0016807] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 12/30/2010] [Indexed: 11/18/2022] Open
Abstract
Background Skeletal muscle is a complex, versatile tissue composed of a variety of functionally diverse fiber types. Although the biochemical, structural and functional properties of myofibers have been the subject of intense investigation for the last decades, understanding molecular processes regulating fiber type diversity is still complicated by the heterogeneity of cell types present in the whole muscle organ. Methodology/Principal Findings We have produced a first catalogue of genes expressed in mouse slow-oxidative (type 1) and fast-glycolytic (type 2B) fibers through transcriptome analysis at the single fiber level (microgenomics). Individual fibers were obtained from murine soleus and EDL muscles and initially classified by myosin heavy chain isoform content. Gene expression profiling on high density DNA oligonucleotide microarrays showed that both qualitative and quantitative improvements were achieved, compared to results with standard muscle homogenate. First, myofiber profiles were virtually free from non-muscle transcriptional activity. Second, thousands of muscle-specific genes were identified, leading to a better definition of gene signatures in the two fiber types as well as the detection of metabolic and signaling pathways that are differentially activated in specific fiber types. Several regulatory proteins showed preferential expression in slow myofibers. Discriminant analysis revealed novel genes that could be useful for fiber type functional classification. Conclusions/Significance As gene expression analyses at the single fiber level significantly increased the resolution power, this innovative approach would allow a better understanding of the adaptive transcriptomic transitions occurring in myofibers under physiological and pathological conditions.
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Affiliation(s)
- Francesco Chemello
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
| | - Camilla Bean
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
| | - Pasqua Cancellara
- Department of Anatomy and Physiology, University of Padova, Padova, Italy
| | - Paolo Laveder
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
| | - Carlo Reggiani
- Department of Anatomy and Physiology, University of Padova, Padova, Italy
| | - Gerolamo Lanfranchi
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
- * E-mail:
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Abstract
Muscle performance is in part dictated by muscle fibre composition and a precise understanding of the genetic and acquired factors that determine the fibre type profile is important in sport science, but is also relevant to neuromuscular diseases and to metabolic diseases, such as type 2 diabetes. The dissection of the signalling pathways that determine or modulate the muscle fibre phenotype has thus potential clinical significance. In this brief review, I examine the evolution of the notion of muscle fibre types, discuss some aspects related to species differences, point at problems in the interpretation of transgenic and knockout models and show how in vivo transfection can be used to identify regulatory factors involved in fibre type diversification, focusing on the calcineurin-nuclear factor of activated T cells (NFAT) pathway.
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Affiliation(s)
- S Schiaffino
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
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Arbanas J, Klasan GS, Nikolic M, Jerkovic R, Miljanovic I, Malnar D. Fibre type composition of the human psoas major muscle with regard to the level of its origin. J Anat 2010; 215:636-41. [PMID: 19930517 DOI: 10.1111/j.1469-7580.2009.01155.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The aim of our study was to explore the fibre type composition of the human psoas major muscle at different levels of its origin, from the first lumbar to the fourth lumbar vertebra, and to compare the muscle fibre size and distribution of different fibre types between levels with respect to its complex postural and dynamic function. Muscle samples were collected from 15 young males (younger than 35 years). Serial transverse sections (5 microm) of the samples were cut by cryomicrotome. Type I, IIA and IIX muscle fibres were typed using myosin heavy chain identification. The serial sections were analysed using a light microscope with a magnitude of 100x. The differences between measurements were evaluated using a repeated-measures anova and Scheffé test for post-hoc analysis. Our study showed that the human psoas major muscle was composed of type I, IIA and IIX muscle fibres. It had a predominance of type IIA muscle fibres, whereas type I muscle fibres had the largest cross-sectional area. Type IIX muscle fibres were present as a far smaller percentage and had the smallest cross-sectional area. Moreover, the fibre type composition of the psoas major muscle was different between levels of its origin starting from the first lumbar to the fourth lumbar vertebra. We conclude that the fibre type composition of the psoas major muscle indicated its dynamic and postural functions, which supports the fact that it is the main flexor of the hip joint (dynamic function) and stabilizer of the lumbar spine, sacroiliac and hip joints (postural function). The cranial part of the psoas major muscle has a primarily postural role, whereas the caudal part of the muscle has a dynamic role.
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Affiliation(s)
- Juraj Arbanas
- Department of Anatomy, School of Medicine, University of Rijeka, 51000 Rijeka, Croatia.
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Hesse B, Fischer MS, Schilling N. Distribution pattern of muscle fiber types in the perivertebral musculature of two different sized species of mice. Anat Rec (Hoboken) 2010; 293:446-63. [PMID: 20169566 DOI: 10.1002/ar.21090] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Many physiological parameters scale with body size. Regarding limb muscles, it has been shown that the demands for relatively faster muscles, less postural work, and greater heat production in small mammals are met by lower proportions of Type I and conversely higher proportions of Type II fibers. To investigate possible adaptations of the perivertebral musculature, we investigated the proportion, spatial distribution, and cross-sectional area (csa) of the different muscle fiber types in the laboratory and harvest mouse. Serial cross sections from the posterior thoracic to the lumbo-sacral region were prepared and Type I, IIA, and IIB fibers identified using enzymehistochemistry. The general distribution of Type I and IIB fibers, as well as the more or less equal distribution of IIA fibers, resembles the pattern found in other mammals. However, the overall proportion of Type I fibers was very low in the laboratory mouse and particularly low in the harvest mouse. Muscular adaptations to a small body size were met primarily by increased Type IIA fiber proportions. Thereby, not all muscles or muscle regions similarly reflected the expected scaling effects. However, our results clearly show that body size is a critical factor when fiber-type proportions are compared among different sized mammals.
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Affiliation(s)
- Bettina Hesse
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, Germany.
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Almosnino S, Pelland L, Pedlow SV, Stevenson JM. Between-day reliability of electromechanical delay of selected neck muscles during performance of maximal isometric efforts. BMC Sports Sci Med Rehabil 2009; 1:22. [PMID: 19775461 PMCID: PMC2764695 DOI: 10.1186/1758-2555-1-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 09/23/2009] [Indexed: 11/26/2022]
Abstract
Background The purpose of this study was to assess the between-day reliability of the electromechanical delay (EMD) of selected neck muscles during the performance of maximal isometric contractions in five different directions. Methods Twenty-one physically active males participated in two testing sessions separated by seven to eight days. Using a custom-made fixed frame dynamometer, cervical force and surface electromyography (EMG) were recorded bilaterally from the splenius capitis, upper trapezius and sternocleidomastoid muscles during the performance of efforts in extension, flexion, left and right lateral bending, and protraction. The EMD was extracted using the Teager-Kaiser Energy Operator. Reliability indices calculated for each muscle in each testing direction were: the difference in scores between the two testing sessions and corresponding 95% confidence intervals, the standard error of measurement (SEM) and intra-class correlation coefficients (ICC). Results EMD values showed no evidence of systematic difference between the two testing sessions across all muscles and testing directions. The SEM for extension, flexion and lateral bending efforts ranged between 2.5 ms to 4.8 ms, indicating a good level of measurement precision. For protraction, SEM values were higher and considered to be imprecise for research and clinical purposes. ICC values for all muscles across all testing directions ranged from 0.23 to 0.79. Conclusion EMD of selected neck muscles can be measured with sufficient precision for the assessment of neck muscle function in an athletic population in the majority of directions tested.
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Affiliation(s)
- Sivan Almosnino
- School of Rehabilitation Therapy, Queen's University, Kingston, ON, Canada.
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Rannou F, Droguet M, Giroux-Metges MA, Pennec Y, Gioux M, Pennec JP. Differences in sodium voltage-gated channel properties according to myosin heavy chain isoform expression in single muscle fibres. J Physiol 2009; 587:5249-58. [PMID: 19752118 DOI: 10.1113/jphysiol.2009.176446] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The myosin heavy chain (MHC) isoform determines the characteristics and shortening velocity of muscle fibres. The functional properties of the muscle fibre are also conditioned by its membrane excitability through the electrophysiological properties of sodium voltage-gated channels. Macropatch-clamp is used to study sodium channels in fibres from peroneus longus (PL) and soleus (Sol) muscles (Wistar rats, n = 8). After patch-clamp recordings, single fibres are identified by SDS-PAGE electrophoresis according to their myosin heavy chain isoform (slow type I and the three fast types IIa, IIx, IIb). Characteristics of sodium currents are compared (Student's t test) between fibres exhibiting only one MHC isoform. Four MHC isoforms are identified in PL and only type I in Sol single fibres. In PL, maximal sodium current (I(max)), maximal sodium conductance (g(Na,max)) and time constants of activation and inactivation ((m) and (h)) increase according to the scheme I-->IIa-->IIx-->IIb (P < 0.05). (m) values related to sodium channel type and/or function, are similar in Sol I and PL IIb fibres (P = 0.97) despite different contractile properties. The voltage dependence of activation (V(a,1/2)) shows a shift towards positive potentials from Sol type I to IIa, IIx and finally IIb fibres from PL (P < 0.05). These data are consistent with the earlier recruitment of slow fibres in a fast-mixed muscle like PL, while slow fibres of postural muscle such as soleus could be recruited in the same ways as IIb fibres in a fast muscle.
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Affiliation(s)
- F Rannou
- Université de Brest, Faculté de Médecine et des Sciences de la Santé, EA 4326, Laboratoire de Physiologie, Brest, F-29200 France
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Jouanin JC, Pérès M, Ducorps A, Renault B. A dynamic network involving M1-S1, SII-insular, medial insular, and cingulate cortices controls muscular activity during an isometric contraction reaction time task. Hum Brain Mapp 2009; 30:675-88. [PMID: 18266218 DOI: 10.1002/hbm.20534] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Magnetoencephalographic, electromyographic (EMG), work, and reaction time (RT) were recorded from nine subjects during visually triggered intermittent isometric contractions of the middle finger under two conditions: unloaded and loaded (30% of maximal voluntary contraction). The effect of muscle fatigue was studied over three consecutive periods under both conditions. In the loaded condition, the motor evoked field triggered by the EMG onset decreased with fatigue, whereas movement-evoked fields (MEFs) increased (P < 0.01). Fatigue was demonstrated in the loaded condition, since (i) RT increased due to an increase in the electromechanical delay (P < 0.002); (ii) work decreased from Periods 1 to 3 (P < 0.005), while (iii) the myoelectric RMS amplitude of both flexor digitorum superficialis and extensor muscles increased (P < 0.003) and (iv) during Period 3, the spectral deflection of the EMG median frequency of the FDS muscle decreased (P < 0.001). In the unloaded condition and at the beginning of the loaded condition, a parallel network including M1-S1, posterior SII-insular, and posterior cingulate cortices accounted for the MEF activities. However, under the effect of fatigue, medial insular and posterior cingulate cortices drove this network. Moreover, changes in the location of insular and M1-S1 activations were significantly correlated with muscle fatigue (increase of RMS-EMG; P < 0.03 and P < 0.01, respectively). These results demonstrate that a plastic network controls the strength of the motor command as fatigue occurs: sensory information, pain, and exhaustion act through activation of the medial insular and posterior cingulate cortices to decrease the motor command in order to preserve muscle efficiency and integrity.
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Affiliation(s)
- Jean-Claude Jouanin
- Department of Integrated Physiology, Aerospace Medical Institute of Health, Brétigny-sur-Orge, France.
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Waardenberg AJ, Reverter A, Wells CA, Dalrymple BP. Using a 3D virtual muscle model to link gene expression changes during myogenesis to protein spatial location in muscle. BMC SYSTEMS BIOLOGY 2008; 2:88. [PMID: 18945372 PMCID: PMC2596796 DOI: 10.1186/1752-0509-2-88] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 10/22/2008] [Indexed: 11/23/2022]
Abstract
Background Myogenesis is an ordered process whereby mononucleated muscle precursor cells (myoblasts) fuse into multinucleated myotubes that eventually differentiate into myofibres, involving substantial changes in gene expression and the organisation of structural components of the cells. To gain further insight into the orchestration of these structural changes we have overlaid the spatial organisation of the protein components of a muscle cell with their gene expression changes during differentiation using a new 3D visualisation tool: the Virtual Muscle 3D (VMus3D). Results Sets of generic striated muscle costamere, Z-disk and filament proteins were constructed from the literature and protein-interaction databases. Expression profiles of the genes encoding these proteins were obtained from mouse C2C12 cells undergoing myogenesis in vitro, as well as a mouse tissue survey dataset. Visualisation of the expression data in VMus3D yielded novel observations with significant relationships between the spatial location and the temporal expression profiles of the structural protein products of these genes. A muscle specificity index was calculated based on muscle expression relative to the median expression in all tissues and, as expected, genes with the highest muscle specificity were also expressed most dynamically during differentiation. Interestingly, most genes encoding costamere as well as some Z-disk proteins appeared to be broadly expressed across most tissues and showed little change in expression during muscle differentiation, in line with the broader cellular role described for some of these proteins. Conclusion By studying gene expression patterns from a structural perspective we have demonstrated that not all genes encoding proteins that are part of muscle specific structures are simply up-regulated during muscle cell differentiation. Indeed, a group of genes whose expression program appears to be minimally affected by the differentiation process, code for proteins participating in vital skeletal muscle structures. Expression alone is a poor metric of gene behaviour. Instead, the "connectivity model of muscle development" is proposed as a mechanism for muscle development: whereby the closer to the myofibril core of muscle cells, the greater the gene expression changes during muscle differentiation and the greater the muscle specificity.
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Affiliation(s)
- Ashley J Waardenberg
- CSIRO, Food Futures Flagship, Queensland Bioscience Precinct, 306 Carmody Road, St, Lucia, QLD 4067, Australia.
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Muscle-Specific PPARbeta/delta Agonism May Provide Synergistic Benefits with Life Style Modifications. PPAR Res 2008; 2007:30578. [PMID: 18274626 PMCID: PMC2220041 DOI: 10.1155/2007/30578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 08/08/2007] [Accepted: 11/13/2007] [Indexed: 11/26/2022] Open
Abstract
Peroxisome proliferator-activated receptor β/δ
(PPARβ/δ)
has emerged as a powerful metabolic regulator in diverse tissues
including fat, skeletal muscle, and the heart. It is now
established that activation of
PPARβ/δ
promotes fatty acid oxidation in several tissues, such as skeletal
muscle and adipose tissue. In muscle,
PPARβ/δ
appears to act as a central regulator of fatty acid catabolism.
PPARβ/δ contents are increased in muscle during physiological situations
such as physical exercise or long-term fasting, characterized by
increased fatty acid oxidation. Targeted expression of an
activated form of PPARβ/δ
in skeletal muscle induces a switch to form increased numbers of
type I muscle fibers resembling the fiber type transition by
endurance training. Activation of
PPARβ/δ
also enhances mitochondrial capacity and fat oxidation in the
skeletal muscle that resembles the effect of regular exercise.
Therefore, it is hypothesized that muscle-specific
PPARβ/δ
agonists could be a key strategy to support the poor
cardiorespiratory fitness associated with metabolic disorders.
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Donato ME, Schiavi J, Ulerich AD, Weaver FE, Coughlin DJ. Myosin regulatory light chain expression in trout muscle. ACTA ACUST UNITED AC 2008; 309:64-72. [DOI: 10.1002/jez.433] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Rabøl R, Boushel R, Dela F. Mitochondrial oxidative function and type 2 diabetes. Appl Physiol Nutr Metab 2007; 31:675-83. [PMID: 17213881 DOI: 10.1139/h06-071] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cause of insulin resistance and type 2 diabetes is unknown. The major part of insulin-mediated glucose disposal takes place in the skeletal muscle, and increased amounts of intramyocellular lipid has been associated with insulin resistance and linked to decreased activity of mitochondrial oxidative phosphorylation. This review will cover the present knowledge and literature on the topics of the activity of oxidative enzymes and the electron transport chain (ETC) in skeletal muscle of patients with type 2 diabetes. Different methods of studying mitochondrial function are described, including biochemical measurements of oxidative enzyme and electron transport activity, isolation of mitochondria for measurements of respiration, and ATP production and indirect measurements of ATP production using nuclear magnetic resonance (NMR) - spectroscopy. Biochemical markers of mitochondrial content are also discussed. Several studies show reduced activity of oxidative enzymes in skeletal muscle of type 2 diabetics. The reductions are independent of muscle fiber type, and are accompanied by visual evidence of damaged mitochondria. In most studies, the reduced oxidative enzyme activity is explained by decreases in mitochondrial content; thus, evidence of a functional impairment in mitochondria in type 2 diabetes is not convincing. These impairments in oxidative function and mitochondrial morphology could reflect the sedentary lifestyle of the diabetic subjects, and the influence of physical activity on oxidative activity and mitochondrial function is discussed. The studies on insulin-resistant offspring of type 2 diabetic parents have provided important insights in the earliest metabolic defects in type 2 diabetes. These defects include reductions in basal ATP production and an attenuated response to insulin stimulation. The decreased basal ATP production does not affect overall lipid or glucose oxidation, and no studies linking changes in oxidative activity and insulin sensitivity in type 2 diabetes have been published. It is concluded that evidence of a functional impairment in mitochondria in type 2 diabetes is not convincing, and that intervention studies describing the correlation between changes in insulin resistance and mitochondrial function in type 2 diabetes are lacking. Specific effects of regular physical training and muscular work on mitochondrial function and plasticity in type 2 diabetes remain an important area of research.
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Affiliation(s)
- Rasmus Rabøl
- The Copenhagen Muscle Research Centre, The Panum Institute, Department of Medical Physiology, University of Copenhagen, Blegdamsvej 3, DK 2200 Copenhagen N, Denmark.
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Strbenc M, Smerdu V, Pogacnik A, Fazarinc G. Myosin heavy chain isoform transitions in canine skeletal muscles during postnatal growth. J Anat 2007; 209:149-63. [PMID: 16879596 PMCID: PMC2100321 DOI: 10.1111/j.1469-7580.2006.00599.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
To gain a better understanding of the normal characteristics of developing canine muscles, myosin heavy chain (MHC) isoform expression was analysed in the axial and limb skeletal muscles of 18 young dogs whose ages ranged from the late prenatal stage to 6 months. We compared the results of immunohistochemistry using ten monoclonal antibodies, specific to different MHC isoforms, and enzyme-histochemical reactions, which demonstrate the activity of myofibrillar ATPase, succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (alpha-GPDH). In the skeletal muscles of fetuses and neonatal dogs the developmental isoforms MHC-emb and MHC-neo were prevalent. In all muscles the primary fibres, located centrally in each muscle fascicle, strongly expressed the slow isoform MHC-I. The adult fast isoform MHC-IIa was first noted in some of the secondary fibres on fetal day 55. During the first 10 days after birth, the expression of MHC-emb declined, as did that of MHC-neo during the second and third weeks. Correspondingly, the expression of MHC-IIa, and later, of MHC-I increased in the secondary fibres. Between the sixth week and second month the expression of MHC-IIx became prominent. The slow rhomboideus muscle exhibited an early expression of the slow isoform in the secondary fibres. Our results indicate that the timing of muscle maturation depends on its activity immediately following birth. The fastest developing muscle was the diaphragm, followed by the fast muscles. A pronounced changeover from developmental to adult isoforms was noted at 4-6 weeks of age, which coincides with the increased physical activity of puppies.
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MESH Headings
- Adenosine Triphosphatases/metabolism
- Animals
- Animals, Newborn
- Dogs
- Glycerolphosphate Dehydrogenase/metabolism
- Muscle Fibers, Fast-Twitch/cytology
- Muscle Fibers, Fast-Twitch/enzymology
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/cytology
- Muscle Fibers, Slow-Twitch/enzymology
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/growth & development
- Muscle, Skeletal/metabolism
- Myosin Heavy Chains/metabolism
- Protein Isoforms
- Succinate Dehydrogenase/metabolism
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Affiliation(s)
- Malan Strbenc
- Institute of Anatomy, Histology and Embryology, Veterinary Faculty, University of Ljubljana, Slovenia
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Østergård T, Jessen N, Schmitz O, Mandarino LJ. The effect of exercise, training, and inactivity on insulin sensitivity in diabetics and their relatives: what is new? Appl Physiol Nutr Metab 2007; 32:541-8. [PMID: 17510695 DOI: 10.1139/h07-031] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Insulin resistance is a hallmark characteristic of type 2 diabetes. However, in healthy first-degree relatives of type 2 diabetics, insulin resistance is often present years before glucose intolerance or diabetes becomes clinically manifest. The mechanisms of insulin resistance involve conditions leading to an increased supply of fatty acids (e.g., high energy intake, obesity) and conditions in which the degradation/oxidation of muscular fatty acids is impaired. Several large-scale studies have documented the fact that increased physical activity can reduce or at least postpone the development of type 2 diabetes, and low physical fitness is a clear independent risk factor for the development of type 2 diabetes. The mechanisms responsible for the improvement in insulin sensitivity after exercise training have been studied extensively, but are not fully understood. This review focuses on insulin resistance in skeletal muscle and, in particular, its relation to changes in aerobic fitness in type 2 diabetics and their first-degree relatives.
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Affiliation(s)
- Torben Østergård
- Department of Medicine M (Endocrinology and Diabetes), Aarhus University Hospital, Denmark.
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Wank V, Fischer MS, Walter B, Bauer R. Muscle growth and fiber type composition in hind limb muscles during postnatal development in pigs. Cells Tissues Organs 2006; 182:171-81. [PMID: 16914919 DOI: 10.1159/000093966] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2006] [Indexed: 11/19/2022] Open
Abstract
Rapid postnatal development in pigs is reflected by differentiation in skeletal muscle. This process depends on muscle function and demands, but a comprehensive overview of individual developmental characteristics of quickly growing leg muscles in pigs is still missing. This study focused on the development of 10 hind limb muscles in pigs. To determine these changes in mass, fiber type patterns and fiber diameters were analyzed 0, 2, 4, 7, 14, 28, 42, 56 and 400 days after birth. Generally, the proportion of slow fibers increased from birth to 8 weeks. Thereafter, only minor changes in muscle fiber type composition were observed. The majority of the muscles contained less then 10% slow-twitch fibers at birth, increasing to between 12 (Musculus vastus lateralis) and 38% (M. gastrocnemius medialis) in adult pigs. By contrast, postural muscles already had 20-30% slow fibers at birth, and this contribution increased up to 65% in adults (i.e. M. vastus intermedius). From birth to the 2nd week, only in slow fibers could activity of oxidative enzymes be detected. A differentiation of fast-twitch fibers into subtypes with high (comparable to type IIA) and low oxidative metabolism (equivalent to type IIB) occurred between the 2nd and 4th week of life. The ratio between type II fibers with high and low oxidative enzyme activity did not change markedly through development in any muscle, although there was a trend towards an increasing proportion of type IIA fibers in the soleus. In the majority of the muscles investigated, the fast-twitch fibers with low oxidative metabolism (IIB) obtained the largest cross-sectional area. In contrast, at birth no remarkable differences in the diameter of fast and slow fibers were found. The rapid increase in muscle mass compared to body mass reflects the high performance in meat production of the cross pig investigated.
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Affiliation(s)
- Veit Wank
- Institute of Sports and Sports Science, Eberhard Karls University, Tubingen, Germany
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