1
|
Ng YK, Blazev R, McNamara JW, Dutt M, Molendijk J, Porrello ER, Elliott DA, Parker BL. Affinity Purification-Mass Spectrometry and Single Fiber Physiology/Proteomics Reveals Mechanistic Insights of C18ORF25. J Proteome Res 2024; 23:1285-1297. [PMID: 38480473 DOI: 10.1021/acs.jproteome.3c00716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
C18ORF25 was recently shown to be phosphorylated at S67 by AMP-activated protein kinase (AMPK) in the skeletal muscle, following acute exercise in humans. Phosphorylation was shown to improve the ex vivo skeletal muscle contractile function in mice, but our understanding of the molecular mechanisms is incomplete. Here, we profiled the interactome of C18ORF25 in mouse myotubes using affinity purification coupled to mass spectrometry. This analysis included an investigation of AMPK-dependent and S67-dependent protein/protein interactions. Several nucleocytoplasmic and contractile-associated proteins were identified, which revealed a subset of GTPases that associate with C18ORF25 in an AMPK- and S67 phosphorylation-dependent manner. We confirmed that C18ORF25 is localized to the nucleus and the contractile apparatus in the skeletal muscle. Mice lacking C18Orf25 display defects in calcium handling specifically in fast-twitch muscle fibers. To investigate these mechanisms, we developed an integrated single fiber physiology and single fiber proteomic platform. The approach enabled a detailed assessment of various steps in the excitation-contraction pathway including SR calcium handling and force generation, followed by paired single fiber proteomic analysis. This enabled us to identify >700 protein/phenotype associations and 36 fiber-type specific differences, following loss of C18Orf25. Taken together, our data provide unique insights into the function of C18ORF25 and its role in skeletal muscle physiology.
Collapse
Affiliation(s)
- Yaan-Kit Ng
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, 3052 VIC, Australia
- Centre for Muscle Research, The University of Melbourne, Parkville, 3052 VIC, Australia
| | - Ronnie Blazev
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, 3052 VIC, Australia
- Centre for Muscle Research, The University of Melbourne, Parkville, 3052 VIC, Australia
| | - James W McNamara
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, 3052 VIC, Australia
- Centre for Muscle Research, The University of Melbourne, Parkville, 3052 VIC, Australia
- Murdoch Children's Research Institute and Melbourne Centre for Cardiovascular Genomics and Regenerative Medicine, The Royal Children's Hospital, Parkville, 3052 VIC, Australia
- Melbourne Centre for Cardiovascular Genomics and Regenerative Medicine, The Royal Children's Hospital, Melbourne, 3052 VIC, Australia
- Novo Nordisk Foundation Center for Stem Cell Medicine, Murdoch Children's Research Institute, Melbourne, 3052 VIC, Australia
| | - Mriga Dutt
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, 3052 VIC, Australia
- Centre for Muscle Research, The University of Melbourne, Parkville, 3052 VIC, Australia
| | - Jeffrey Molendijk
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, 3052 VIC, Australia
- Centre for Muscle Research, The University of Melbourne, Parkville, 3052 VIC, Australia
| | - Enzo R Porrello
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, 3052 VIC, Australia
- Murdoch Children's Research Institute and Melbourne Centre for Cardiovascular Genomics and Regenerative Medicine, The Royal Children's Hospital, Parkville, 3052 VIC, Australia
- Melbourne Centre for Cardiovascular Genomics and Regenerative Medicine, The Royal Children's Hospital, Melbourne, 3052 VIC, Australia
- Novo Nordisk Foundation Center for Stem Cell Medicine, Murdoch Children's Research Institute, Melbourne, 3052 VIC, Australia
- Department of Paediatrics, Faculty of Medicine, Dentistry & Health Sciences, The University of Melbourne, Melbourne, 3010 VIC, Australia
| | - David A Elliott
- Murdoch Children's Research Institute and Melbourne Centre for Cardiovascular Genomics and Regenerative Medicine, The Royal Children's Hospital, Parkville, 3052 VIC, Australia
- Melbourne Centre for Cardiovascular Genomics and Regenerative Medicine, The Royal Children's Hospital, Melbourne, 3052 VIC, Australia
- Novo Nordisk Foundation Center for Stem Cell Medicine, Murdoch Children's Research Institute, Melbourne, 3052 VIC, Australia
- Department of Paediatrics, Faculty of Medicine, Dentistry & Health Sciences, The University of Melbourne, Melbourne, 3010 VIC, Australia
| | - Benjamin L Parker
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, 3052 VIC, Australia
- Centre for Muscle Research, The University of Melbourne, Parkville, 3052 VIC, Australia
| |
Collapse
|
2
|
Gerzen OP, Votinova VO, Potoskueva IK, Tzybina AE, Nikitina LV. Direct Effects of Toxic Divalent Cations on Contractile Proteins with Implications for the Heart: Unraveling Mechanisms of Dysfunction. Int J Mol Sci 2023; 24:10579. [PMID: 37445756 DOI: 10.3390/ijms241310579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/19/2023] [Accepted: 06/22/2023] [Indexed: 07/15/2023] Open
Abstract
The binding of calcium and magnesium ions to proteins is crucial for regulating heart contraction. However, other divalent cations, including xenobiotics, can accumulate in the myocardium and enter cardiomyocytes, where they can bind to proteins. In this article, we summarized the impact of these cations on myosin ATPase activity and EF-hand proteins, with special attention given to toxic cations. Optimal binding to EF-hand proteins occurs at an ionic radius close to that of Mg2+ and Ca2+. In skeletal Troponin C, Cd2+, Sr2+, Pb2+, Mn2+, Co2+, Ni2+, Ba2+, Mg2+, Zn2+, and trivalent lanthanides can substitute for Ca2+. As myosin ATPase is not a specific MgATPase, Ca2+, Fe2+, Mn2+, Ni2+, and Sr2+ could support myosin ATPase activity. On the other hand, Zn2+ and Cu2 significantly inhibit ATPase activity. The affinity to various divalent cations depends on certain proteins or their isoforms and can alter with amino acid substitution and post-translational modification. Cardiac EF-hand proteins and the myosin ATP-binding pocket are potential molecular targets for toxic cations, which could significantly alter the mechanical characteristics of the heart muscle at the molecular level.
Collapse
Affiliation(s)
- Oksana P Gerzen
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, 620049 Ekaterinburg, Russia
| | - Veronika O Votinova
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, 620049 Ekaterinburg, Russia
| | - Iulia K Potoskueva
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, 620049 Ekaterinburg, Russia
| | - Alyona E Tzybina
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, 620049 Ekaterinburg, Russia
| | - Larisa V Nikitina
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, 620049 Ekaterinburg, Russia
| |
Collapse
|
3
|
Blazev R, Carl CS, Ng YK, Molendijk J, Voldstedlund CT, Zhao Y, Xiao D, Kueh AJ, Miotto PM, Haynes VR, Hardee JP, Chung JD, McNamara JW, Qian H, Gregorevic P, Oakhill JS, Herold MJ, Jensen TE, Lisowski L, Lynch GS, Dodd GT, Watt MJ, Yang P, Kiens B, Richter EA, Parker BL. Phosphoproteomics of three exercise modalities identifies canonical signaling and C18ORF25 as an AMPK substrate regulating skeletal muscle function. Cell Metab 2022; 34:1561-1577.e9. [PMID: 35882232 DOI: 10.1016/j.cmet.2022.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/31/2022] [Accepted: 07/08/2022] [Indexed: 11/03/2022]
Abstract
Exercise induces signaling networks to improve muscle function and confer health benefits. To identify divergent and common signaling networks during and after different exercise modalities, we performed a phosphoproteomic analysis of human skeletal muscle from a cross-over intervention of endurance, sprint, and resistance exercise. This identified 5,486 phosphosites regulated during or after at least one type of exercise modality and only 420 core phosphosites common to all exercise. One of these core phosphosites was S67 on the uncharacterized protein C18ORF25, which we validated as an AMPK substrate. Mice lacking C18ORF25 have reduced skeletal muscle fiber size, exercise capacity, and muscle contractile function, and this was associated with reduced phosphorylation of contractile and Ca2+ handling proteins. Expression of C18ORF25 S66/67D phospho-mimetic reversed the decreased muscle force production. This work defines the divergent and canonical exercise phosphoproteome across different modalities and identifies C18ORF25 as a regulator of exercise signaling and muscle function.
Collapse
Affiliation(s)
- Ronnie Blazev
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | - Christian S Carl
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, The University of Copenhagen, Copenhagen, Denmark
| | - Yaan-Kit Ng
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | - Jeffrey Molendijk
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | - Christian T Voldstedlund
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, The University of Copenhagen, Copenhagen, Denmark
| | - Yuanyuan Zhao
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Di Xiao
- Children's Medical Research Institute, The University of Sydney, Camperdown, NSW, Australia; School of Mathematics and Statistics, The University of Sydney, Camperdown, NSW, Australia
| | - Andrew J Kueh
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Paula M Miotto
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Vanessa R Haynes
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Justin P Hardee
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | - Jin D Chung
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | - James W McNamara
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia; Murdoch Children's Research Institute and Melbourne Centre for Cardiovascular Genomics and Regenerative Medicine, The Royal Children's Hospital, Parkville, VIC, Australia
| | - Hongwei Qian
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | - Paul Gregorevic
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | | | - Marco J Herold
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Thomas E Jensen
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, The University of Copenhagen, Copenhagen, Denmark
| | - Leszek Lisowski
- Children's Medical Research Institute, The University of Sydney, Camperdown, NSW, Australia; Military Institute of Medicine, Warsaw, Poland
| | - Gordon S Lynch
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia
| | - Garron T Dodd
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Matthew J Watt
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Pengyi Yang
- Children's Medical Research Institute, The University of Sydney, Camperdown, NSW, Australia; The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Bente Kiens
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, The University of Copenhagen, Copenhagen, Denmark.
| | - Erik A Richter
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, The University of Copenhagen, Copenhagen, Denmark.
| | - Benjamin L Parker
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC, Australia; Centre for Muscle Research, The University of Melbourne, Parkville, VIC, Australia.
| |
Collapse
|
4
|
Rudayni HA, Stephenson G, Posterino GS. Measurements of basal d-glucose transport through GLUT1 across the intact plasma membrane of isolated segments from single fast- and slow-twitch skeletal muscle fibres of rat. Acta Physiol (Oxf) 2022; 234:e13789. [PMID: 35038771 PMCID: PMC9541404 DOI: 10.1111/apha.13789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 01/09/2022] [Accepted: 01/12/2022] [Indexed: 12/24/2022]
Abstract
Aim To develop a method for direct measurement of the fluorescent d‐glucose analogue 2‐NBDG transport across the plasma membrane of single skeletal muscle fibres and derive the theoretical framework for determining the kinetic parameters for d‐glucose transport under basal conditions. Methods A novel method is described for measuring free 2‐NBDG transport across plasma membrane of single rat muscle fibres at rest. The 2‐NBDG uptake was >90% suppressed by 100 µM cytochalasin B in both fast‐twitch and slow‐twitch fibres, indicating that the 2‐NBDG transport is GLUT‐mediated. Fibres were identified as fast‐twitch or slow‐twitch based on the differential sensitivity of their contractile apparatus to Sr2+. Results The time course of 2‐NBDG uptake in the presence of 50 µM 2‐NBDG follows a one‐phase exponential plateau curve and is faster in fast‐twitch (rate constant 0.053 ± 0.0024 s‐1) than in slow‐twitch fibres (rate constant 0.031 ± 0.0021 s‐1). The rate constants were markedly reduced in the presence of 20 mM d‐glucose to 0.0082 ± 0.0004 s‐1 and 0.0056 ± 0.0002 s‐1 in fast‐twitch and slow‐twitch fibres respectively. 2‐NBDG transport was asymmetric, consistent with GLUT1 being the major functional GLUT isoform transporting 2‐NBDG in muscle fibres at rest. The parameters describing the transport kinetics for both 2‐NBDG and d‐glucose (dissociation constants, Michaelis–Menten constants, maximal rates of uptake and outflow) were calculated from the measurements made with 2‐NBDG. Conclusion Free 2‐NBDG and d‐glucose transport across the plasma membrane of single rat muscle fibres at rest is fast, conclusively showing that the rate‐limiting step in d‐glucose uptake in skeletal muscle is not necessarily the GLUT‐mediated transport of d‐glucose.
Collapse
Affiliation(s)
- Hassan A. Rudayni
- Department of Biology College of Science Imam Mohammad Ibn Saud Islamic University Riyadh Saudi Arabia
| | - George Stephenson
- Department of Physiology, Anatomy and Microbiology La Trobe University Melbourne Victoria Australia
| | - Giuseppe S. Posterino
- Department of Physiology, Anatomy and Microbiology La Trobe University Melbourne Victoria Australia
| |
Collapse
|
5
|
Lamboley CR, Rouffet DM, Dutka TL, McKenna MJ, Lamb GD. Effects of high-intensity intermittent exercise on the contractile properties of human type I and type II skeletal muscle fibers. J Appl Physiol (1985) 2020; 128:1207-1216. [PMID: 32213115 DOI: 10.1152/japplphysiol.00014.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In vitro studies have shown that alterations in redox state can cause a range of opposing effects on the properties of the contractile apparatus in skeletal muscle fibers. To test whether and how redox changes occurring in vivo affect the contractile properties, vastus lateralis muscle fibers from seven healthy young adults were examined at rest (PRE) and following (POST) high-intensity intermittent cycling exercise. Individual mechanically skinned muscle fibers were exposed to heavily buffered solutions at progressively higher free [Ca2+] to determine their force-Ca2+ relationship. Following acute exercise, Ca2+ sensitivity was significantly decreased in type I fibers (by 0.06 pCa unit) but not in type II fibers (0.01 pCa unit). Specific force decreased after the exercise in type II fibers (-18%) but was unchanged in type I fibers. Treatment with the reducing agent dithiothreitol (DTT) caused a small decrease in Ca2+-sensitivity in type II fibers at PRE (by ∼0.014 pCa units) and a significantly larger decrease at POST (∼0.035 pCa units), indicating that the exercise had increased S-glutathionylation of fast troponin I. DTT treatment also increased specific force (by ∼4%), but only at POST. In contrast, DTT treatment had no effect on either parameter in type I fibers at either PRE or POST. In type I fibers, the decreased Ca2+ sensitivity was not due to reversible oxidative changes and may have contributed to a decrease in power production during vigorous exercises. In type II fibers, exercise-induced redox changes help counter the decline in Ca2+-sensitivity while causing a small decline in maximum force.NEW & NOTEWORTHY This study identified important cellular changes occurring in human skeletal muscle fibers following high-intensity intermittent exercise: 1) a decrease in contractile apparatus Ca2+ sensitivity in type I but not type II fibers, 2) a decrease in specific force only in type II muscle fibers, and 3) a redox-dependent increase in Ca2+ sensitivity occurring only in type II fibers, which would help maintain muscle performance by countering the normal metabolite-induced decline in Ca2+ sensitivity.
Collapse
Affiliation(s)
- Cedric R Lamboley
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia.,School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - David M Rouffet
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia.,Department of Health and Sport Sciences, Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky
| | - Travis L Dutka
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia
| | - Graham D Lamb
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| |
Collapse
|
6
|
Watanabe D, Lamboley CR, Lamb GD. Effects of S-glutathionylation on the passive force-length relationship in skeletal muscle fibres of rats and humans. J Muscle Res Cell Motil 2019; 41:239-250. [PMID: 31679105 DOI: 10.1007/s10974-019-09563-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 10/26/2019] [Indexed: 12/14/2022]
Abstract
This study investigated the effect of S-glutathionylation on passive force in skeletal muscle fibres, to determine whether activity-related redox reactions could modulate the passive force properties of muscle. Mechanically-skinned fibres were freshly obtained from human and rat muscle, setting sarcomere length (SL) by laser diffraction. Larger stretches were required to produce passive force in human fibres compared to rat fibres, but there were no fibre-type differences in either species. When fibres were exposed to glutathione disulfide (GSSG; 20 mM, 15 min) whilst stretched (at a SL where passive force reached ~ 20% of maximal Ca2+-activated force, denoted as SL20 % max), passive force was subsequently decreased at all SLs in both type I and type II fibres of rat and human (e.g., passive force at SL20 % max decreased by 12 to 25%). This decrease was fully reversed by subsequent reducing treatment with dithiothreitol (DTT; 10 mM for 10 min). If freshly skinned fibres were initially treated with DTT, there was an increase in passive force in type II fibres (by 10 ± 3% and 9 ± 2% in rat and human fibres, respectively), but not in type I fibres. These results indicate that (i) S-glutathionylation, presumably in titin, causes a decrease in passive force in skeletal muscle fibres, but the reduction is relatively smaller than that reported in cardiac muscle, (ii) in rested muscle in vivo, there appears to be some level of reversible oxidative modification, probably involving S-glutathionylation of titin, in type II fibres, but not in type I fibres.
Collapse
Affiliation(s)
- Daiki Watanabe
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Australia. .,Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan.
| | - Cedric R Lamboley
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Australia.,School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Graham D Lamb
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Australia
| |
Collapse
|
7
|
Skeletal muscle fibre swelling contributes to force depression in rats and humans: a mechanically-skinned fibre study. J Muscle Res Cell Motil 2019; 40:343-351. [PMID: 31175519 DOI: 10.1007/s10974-019-09521-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 06/03/2019] [Indexed: 10/26/2022]
Abstract
This study investigated the effects of fibre swelling on force production in rat and human skinned muscle fibres, using osmotic compression to reverse the fibre swelling. In mechanically-skinned fibres, the sarcolemma is removed but normal excitation-contraction coupling remains functional. Force responses in mechanically-skinned fibres were examined with and without osmotic compression by polyvinylpyrrolidone 40 kDa (PVP-40) or Dextran 500 kDa (dextran). Fibre diameter increased to 116 ± 2% (mean ± SEM) when rat skinned type II fibres were immersed in the standard intracellular solution, but remained close to the in situ size when 3% (mass/volume) PVP-40 or 4% Dextran were present. Myofibrillar Ca2+ sensitivity, as indicated by pCa50 (- log10[Ca2+] at half-maximal force), was increased in 4% Dextran (0.072 ± 0.007 pCa50 shift), but was not significantly changed in 3% PVP-40. Maximum Ca2+-activated force increased slightly to 103 ± 1% and 104 ± 1% in PVP-40 and Dextran, respectively. Both tetanic and depolarization-induced force responses in rat skinned type II fibres, elicited by electrical stimulation and ion substitution respectively, were increased by ~ 10 to 15% when the fibres were returned to their normal in situ diameter by addition of PVP-40 or Dextran. Interestingly, the potentiation of these force responses in PVP-40 was appreciably greater than could be explained by potentiation of myofibrillar function alone. These results indicate that muscle fibre swelling, as can occur with intense exercise, decreases evoked force responses by reducing both the Ca2+-sensitivity of the contractile apparatus properties and Ca2+ release from the sarcoplasmic reticulum.
Collapse
|
8
|
Lamb GD, Stephenson DG. Measurement of force and calcium release using mechanically skinned fibers from mammalian skeletal muscle. J Appl Physiol (1985) 2018; 125:1105-1127. [DOI: 10.1152/japplphysiol.00445.2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The mechanically skinned (or “peeled”) skeletal muscle fiber technique is a highly versatile procedure that allows controlled examination of each of the steps in the excitation-contraction (EC)-coupling sequence in skeletal muscle fibers, starting with excitation/depolarization of the transverse tubular (T)-system through to Ca2+ release from sarcoplasmic reticulum (SR) and finally force development by the contractile apparatus. It can also show the overall response of the whole EC-coupling sequence together, such as in twitch and tetanic force responses. A major advantage over intact muscle fiber preparations is that it is possible to set and rapidly manipulate the “intracellular” conditions, allowing examination of the effects of key variables (e.g., intracellular pH, ATP levels, redox state, etc.) on each individual step in EC coupling. This Cores of Reproducibility in Physiology (CORP) article describes the rationale, procedures, and experimental details of the various ways in which the mechanically skinned fiber technique is used in our laboratory to examine the physiological mechanisms controlling Ca2+ release and contraction in skeletal muscle fibers and the aberrations and dysfunction occurring with exercise and disease.
Collapse
Affiliation(s)
- Graham D. Lamb
- Department of Physiology, Anatomy, and Microbiology, School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - D. George Stephenson
- Department of Physiology, Anatomy, and Microbiology, School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| |
Collapse
|
9
|
Cannata DJ, Crossley KJ, Barclay CJ, Walker DW, West JM. Contribution of stretch to the change of activation properties of muscle fibers in the diaphragm at the transition from fetal to neonatal life. Front Physiol 2011; 2:109. [PMID: 22232605 PMCID: PMC3248696 DOI: 10.3389/fphys.2011.00109] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 12/06/2011] [Indexed: 12/02/2022] Open
Abstract
The transition from fetal to postnatal life involves clearance of liquid from the lung and airways, and rapid formation of a functional residual capacity. Despite the importance of the diaphragm in this process, the impact of birth on the mechanical and functional activity of its muscle fibers is not known. This study determined the contractile characteristics of individual “skinned” diaphragm fibers from 70 days (0.47) gestation to after birth in sheep. Based on differential sensitivity to the divalent ions calcium (Ca2+) and strontium (Sr2+), all fibers in the fetal diaphragm were classified as “fast,” whereas fibers from the adult sheep diaphragm exhibited a “hybrid” phenotype where both “fast” and “slow” characteristics were present within each single fiber. Transition to the hybrid phenotype occurred at birth, was evident after only 40 min of spontaneous breathing, and could be induced by simple mechanical stretch of diaphragm fibers from near-term fetuses (∼147 days gestation). Both physical stretch of isolated fibers, and mechanical ventilation of the fetal diaphragm in situ, significantly increased sensitivity to Ca2+ and Sr2+, maximum force generating capacity, and decreased passive tension in near-term and preterm fetuses; however, only fibers from near-term fetuses showed a complete transition to a “hybrid” activation profile. These findings suggest that stretch associated with the transition from a liquid to air-filled lung at birth induces physical changes of proteins determining the activation and elastic properties of the diaphragm. These changes may allow the diaphragm to meet the increased mechanical demands of breathing immediately after birth.
Collapse
Affiliation(s)
- David J Cannata
- School of Life and Environmental Sciences, Deakin University Melbourne, VIC, Australia
| | | | | | | | | |
Collapse
|
10
|
Abstract
Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.
Collapse
Affiliation(s)
- Stefano Schiaffino
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
| | - Carlo Reggiani
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
| |
Collapse
|
11
|
Neunhäuserer D, Zebedin M, Obermoser M, Moser G, Tauber M, Niebauer J, Resch H, Galler S. Human skeletal muscle: transition between fast and slow fibre types. Pflugers Arch 2011; 461:537-43. [PMID: 21360037 DOI: 10.1007/s00424-011-0943-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 02/15/2011] [Accepted: 02/17/2011] [Indexed: 10/18/2022]
Abstract
Human skeletal muscles consist of different fibre types: slow fibres (slow twitch or type I) containing the myosin heavy chain isoform (MHC)-I and fast fibres (fast twitch or type II) containing MHC-IIa (type IIA) or MHC-IId (type IID). The following order of decreasing kinetics is known: type IID > type IIA >> type I. This order is especially based on the kinetics of stretch activation, which is the most discriminative property among fibre types. In this study we tested if hybrid fibres containing both MHC-IIa and MHC-I (type C fibres) provide a transition in kinetics between fast (type IIA) and slow fibres (type I). Our data of stretch activation kinetics suggest that type C fibres, with different ratios of MHC-IIa and MHC-I, do not provide a continuous transition. Instead, a specialized group of slow fibres, which we called "transition fibres", seems to provide a transition. Apart of their kinetics of stretch activation, which is most close to that of type IIA, the transition fibres are characterized by large cross-sectional areas and low maximal tensions. The molecular cause for the mechanical properties of the transition fibres is unknown. It is possible that the transition fibres contain an unknown slow MHC isoform, which cannot be separated by biochemical methods. Alternatively, or in addition, isoforms of myofibrillar proteins, other than MHC, and posttranslational modifications of myofibrillar proteins could play a role regarding the characteristics of the transition fibres.
Collapse
Affiliation(s)
- Daniel Neunhäuserer
- Department of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University Salzburg, Lindhofstr. 20, 5020, Salzburg, Austria.
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Ochala J. Ca2+ sensitizers: An emerging class of agents for counterbalancing weakness in skeletal muscle diseases? Neuromuscul Disord 2009; 20:98-101. [PMID: 20006502 DOI: 10.1016/j.nmd.2009.11.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 11/14/2009] [Accepted: 11/17/2009] [Indexed: 11/16/2022]
Abstract
Ca(2+) ions are key regulators of skeletal muscle contraction. By binding to contractile proteins, they initiate a cascade of molecular events leading to cross-bridge formation and ultimately, muscle shortening and force production. The ability of contractile proteins to respond to Ca(2+) attachment, also known as Ca(2+) sensitivity, is often compromised in acquired and congenital skeletal muscle disorders. It constitutes, undoubtedly, a major physiological cause of weakness for patients. In this review, we discuss recent studies giving strong molecular and cellular evidence that pharmacological modulators of some of the contractile proteins, also termed Ca(2+) sensitizers, are efficient agents to improve Ca(2+) sensitivity and function in diseased skeletal muscle cells. In fact, they compensate for the impaired contractile proteins response to Ca(2+) binding. Currently, such Ca(2+) sensitizing compounds are successfully used for reducing problems in cardiac disorders. Therefore, in the future, under certain conditions, these agents may represent an emerging class of agents to enhance the quality of life of patients suffering from skeletal muscle weakness.
Collapse
Affiliation(s)
- Julien Ochala
- Department of Clinical Neurophysiology, Uppsala University Hospital, Sweden.
| |
Collapse
|
13
|
Spencer T, Posterino GS. Sequential effects of GSNO and H2O2 on the Ca2+ sensitivity of the contractile apparatus of fast- and slow-twitch skeletal muscle fibers from the rat. Am J Physiol Cell Physiol 2009; 296:C1015-23. [DOI: 10.1152/ajpcell.00251.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Reactive oxygen species (ROS), such as hydrogen peroxide (H2O2) and nitric oxide (NO), have been shown to differentially alter the Ca2+ sensitivity of the contractile apparatus of fast-twitch skeletal muscle, leading to the proposal that normal muscle function is controlled by perturbations in the amounts of these two groups of molecules ( 28 ). However, no previous studies have examined whether these opposing actions are retained when the contractile apparatus is subjected to both molecule types. Using mechanically skinned fast- and slow-twitch skeletal muscle fibers of the rat, we compared the effects of sequential addition of nitrosoglutathione (GSNO), a NO donor, and H2O2 on the Ca2+ sensitivity of the contractile apparatus. As expected from previous reports in fast-twitch fibers, when added separately, GSNO (1 mM) reduced the Ca2+ sensitivity of the contractile apparatus, whereas H2O2 (10 mM; added during contractions) increased the Ca2+ sensitivity of the contractile apparatus. When added sequentially to the same fiber, such that the oxidation by one molecule (e.g., GSNO) preceded the oxidation by the other (e.g., H2O2), and vice versa, the individual effects of both molecules on the Ca2+ sensitivity were retained. Interestingly, neither molecule had any effect on the Ca2+ sensitivity of slow-twitch skeletal muscle. The data show that H2O2 and GSNO retain the capacity to independently affect the contractile apparatus to modulate force. Furthermore, the absence of effects in slow-twitch muscle may further explain why this fiber type is relatively insensitive to fatigue.
Collapse
|
14
|
Cannata DJ, Finkelstein DI, Gantois I, Teper Y, Drago J, West JM. Altered fast- and slow-twitch muscle fibre characteristics in female mice with a (S248F) knock-in mutation of the brain neuronal nicotinic acetylcholine receptor. J Muscle Res Cell Motil 2009; 30:73-83. [PMID: 19404753 DOI: 10.1007/s10974-009-9177-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Accepted: 04/15/2009] [Indexed: 10/20/2022]
Abstract
We generated a mouse line with a missense mutation (S248F) in the gene (CHRNA4) encoding the alpha4 subunit of neuronal nicotinic acetylcholine receptor (nAChR). Mutant mice demonstrate brief nicotine induced dystonia that resembles the clinical events seen in patients with the same mutation. Drug-induced dystonia is more pronounced in female mice, thus our aim was to determine if the S248F mutation changed the properties of fast- and slow-twitch muscle fibres from female mutant mice. Reverse transcriptase-PCR confirmed CHRNA4 gene expression in the brain but not skeletal muscles in normal and mutant mice. Ca(2+) and Sr(2+) force activation curves were obtained using skinned muscle fibres prepared from slow-twitch (soleus) and fast-twitch (EDL) muscles. Two significant results were found: (1) the (pCa(50) - pSr(50)) value from EDL fibres was smaller in mutant mice than in wild type (1.01 vs. 1.30), (2) the percentage force produced at pSr 5.5 was larger in mutants than in wild type (5.76 vs. 0.24%). Both results indicate a shift to slow-twitch characteristics in the mutant. This conclusion is supported by the identification of the myosin heavy chain (MHC) isoforms. Mutant EDL fibres expressed MHC I (usually only found in slow-twitch fibres) as well as MHC IIa. Despite the lack of spontaneous dystonic events, our findings suggest that mutant mice may be having subclinical events or the mutation results in a chronic alteration to muscle neural input.
Collapse
Affiliation(s)
- David J Cannata
- School of Life and Environmental Sciences, Deakin University, VIC, Australia.
| | | | | | | | | | | |
Collapse
|
15
|
Yatera K, Hsieh J, Hogg JC, Tranfield E, Suzuki H, Shih CH, Behzad AR, Vincent R, van Eeden SF. Particulate matter air pollution exposure promotes recruitment of monocytes into atherosclerotic plaques. Am J Physiol Heart Circ Physiol 2007; 294:H944-53. [PMID: 18083905 DOI: 10.1152/ajpheart.00406.2007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epidemiologic studies have shown an association between exposure to ambient particulate air pollution <10 microm in diameter (PM(10)) and increased cardiovascular morbidity and mortality. We previously showed that PM(10) exposure causes progression of atherosclerosis in coronary arteries. We postulate that the recruitment of monocytes from the circulation into atherosclerotic lesions is a key step in this PM(10)-induced acceleration of atherosclerosis. The study objective was to quantify the recruitment of circulating monocytes into vessel walls and the progression of atherosclerotic plaques induced by exposure to PM(10). Female Watanabe heritable hyperlipidemic rabbits, which naturally develop systemic atherosclerosis, were exposed to PM(10) (EHC-93) or vehicle by intratracheal instillation twice a week for 4 wk. Monocytes, labeled with 5-bromo-2'-deoxyuridine (BrdU) in donors, were transfused to recipient rabbits as whole blood, and the recruitment of BrdU-labeled cells into vessel walls and plaques in recipients was measured by quantitative histological methodology. Exposure to PM(10) caused progression of atherosclerotic lesions in thoracic and abdominal aorta. It also decreased circulating monocyte counts, decreased circulating monocytes expressing high levels of CD31 (platelet endothelial cell adhesion molecule-1) and CD49d (very late antigen-4 alpha-chain), and increased expression of CD54 (ICAM-1) and CD106 (VCAM-1) in plaques. Exposure to PM(10) increased the number of BrdU-labeled monocytes adherent to endothelium over plaques and increased the migration of BrdU-labeled monocytes into plaques and smooth muscle underneath plaques. We conclude that exposure to ambient air pollution particles promotes the recruitment of circulating monocytes into atherosclerotic plaques and speculate that this is a critically important step in the PM(10)-induced progression of atherosclerosis.
Collapse
Affiliation(s)
- Kazuhiro Yatera
- James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, University of British Columbia, Saint Paul's Hospital, Vancouver, British Columbia, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Posterino GS, Dunn SL. Comparison of the effects of inorganic phosphate on caffeine-induced Ca2+ release in fast- and slow-twitch mammalian skeletal muscle. Am J Physiol Cell Physiol 2007; 294:C97-105. [PMID: 17959728 DOI: 10.1152/ajpcell.00155.2007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We compared the effects of 50 mM P(i) on caffeine-induced Ca(2+) release in mechanically skinned fast-twitch (FT) and slow-twitch (ST) skeletal muscle fibers of the rat. The time integral (area) of the caffeine response was reduced by approximately 57% (FT) and approximately 27% (ST) after 30 s of exposure to 50 mM P(i) in either the presence or absence of creatine phosphate (to buffer ADP). Differences in the sarcoplasmic reticulum (SR) Ca(2+) content between FT and ST fibers [ approximately 40% vs. 100% SR Ca(2+) content (pCa 6.7), respectively] did not contribute to the different effects of P(i) observed; underloading the SR of ST fibers so that the SR Ca(2+) content approximated that of FT fibers resulted in an even smaller ( approximately 21%), but not significant, reduction in caffeine-induced Ca(2+) release by P(i). These observed differences between FT and ST fibers could arise from fiber-type differences in the ability of the SR to accumulate Ca(2+)-P(i) precipitate. To test this, fibers were Ca(2+) loaded in the presence of 50 mM P(i). In FT fibers, the maximum SR Ca(2+) content (pCa 6.7) was subsequently increased by up to 13 times of that achieved when loading for 2 min in the absence of P(i). In ST fibers, the SR Ca(2+) content was only doubled. These data show that Ca(2+) release in ST fibers was less affected by P(i) than FT fibers, and this may be due to a reduced capacity of ST SR to accumulate Ca(2+)-P(i) precipitate. This may account, in part, for the fatigue-resistant nature of ST fibers.
Collapse
Affiliation(s)
- Giuseppe S Posterino
- Discipline of Physiology, School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, Australia.
| | | |
Collapse
|
17
|
Birkeland JAK, Swift F, Tovsrud N, Enger U, Lunde PK, Qvigstad E, Levy FO, Sejersted OM, Sjaastad I. Serotonin increases L-type Ca2+ current and SR Ca2+ content through 5-HT4 receptors in failing rat ventricular cardiomyocytes. Am J Physiol Heart Circ Physiol 2007; 293:H2367-76. [PMID: 17660386 DOI: 10.1152/ajpheart.01375.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rats with congestive heart failure (CHF) develop ventricular inotropic responsiveness to serotonin (5-HT), mediated through 5-HT2A and 5-HT4 receptors. Human ventricle is similarly responsive to 5-HT through 5-HT4 receptors. We studied isolated ventricular cardiomyocytes to clarify the effects of 5-HT on intracellular Ca2+ handling. Left-ventricular cardiomyocytes were isolated from male Wistar rats 6 wk after induction of postinfarction CHF. Contractile function and Ca2+ transients were measured in field-stimulated cardiomyocytes, and L-type Ca2+ current ( ICa,L) and sarcoplasmic reticulum (SR) Ca2+ content were measured in voltage-clamped cells. Protein phosphorylation was measured by Western blotting or phosphoprotein gel staining. 5-HT4- and 5-HT2A-receptor stimulation induced a positive inotropic response of 33 and 18% (both P < 0.05) and also increased the Ca2+ transient (44 and 6%, respectively; both P < 0.05). ICa,L and SR Ca2+ content increased only after 5-HT4-receptor stimulation (57 and 65%; both P < 0.05). Phospholamban serine16 (PLB-Ser16) and troponin I phosphorylation increased by 26 and 13% after 5-HT4-receptor stimulation ( P < 0.05). 5-HT2A-receptor stimulation increased the action potential duration and did not significantly change the phosphorylation of PLB-Ser16 or troponin I, but it increased myosin light chain 2 (MLC2) phosphorylation. In conclusion, the positive inotropic response to 5-HT4 stimulation results from increased ICa,L and increased phosphorylation of PLB-Ser16, which increases the SR Ca2+ content. 5-HT4 stimulation is thus, like β-adrenoceptor stimulation, possibly energetically unfavorable in CHF. 5-HT2A-receptor stimulation, previously studied in acute CHF, induces a positive inotropic response also in chronic CHF, probably mediated by MLC2 phosphorylation.
Collapse
MESH Headings
- Action Potentials
- Adrenergic beta-Agonists/pharmacology
- Animals
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/metabolism
- Calcium Signaling/drug effects
- Calcium-Binding Proteins/metabolism
- Cardiac Myosins
- Cardiotonic Agents/metabolism
- Coronary Vessels/surgery
- Disease Models, Animal
- Heart Failure/etiology
- Heart Failure/metabolism
- Heart Failure/physiopathology
- Indoles/pharmacology
- Isoproterenol/pharmacology
- Ketanserin/pharmacology
- Ligation
- Male
- Myocardial Contraction
- Myocardial Infarction/complications
- Myocardial Infarction/metabolism
- Myocardial Infarction/physiopathology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myosin Light Chains
- Phosphorylation
- Rats
- Rats, Wistar
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptors, Serotonin, 5-HT4/metabolism
- Sarcoplasmic Reticulum/drug effects
- Sarcoplasmic Reticulum/metabolism
- Serotonin/metabolism
- Serotonin 5-HT2 Receptor Antagonists
- Serotonin 5-HT4 Receptor Antagonists
- Serotonin Antagonists/pharmacology
- Sulfonamides/pharmacology
- Time Factors
- Troponin I/metabolism
- Ventricular Function/drug effects
Collapse
Affiliation(s)
- Jon Arne Kro Birkeland
- Institute for Experimental Medical Research, Ullevaal Univ. Hospital, Kirkeveien 166, 0407 Oslo, Norway.
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Cozzi E, Hazarika S, Stallings HW, Cascio WE, Devlin RB, Lust RM, Wingard CJ, Van Scott MR. Ultrafine particulate matter exposure augments ischemia-reperfusion injury in mice. Am J Physiol Heart Circ Physiol 2006; 291:H894-903. [PMID: 16582015 DOI: 10.1152/ajpheart.01362.2005] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epidemiological studies have linked ambient particulate matter (PM) levels to an increased incidence of adverse cardiovascular events. Yet little is definitively known about the mechanisms accounting for the cardiovascular events associated with PM exposure. The goal of this study was to determine the effects of ultrafine (<0.1 μm) PM exposure on ischemia-reperfusion (I/R) injury. ICR mice were exposed to 100 μg of PM or vehicle by intratracheal instillation. Twenty-four hours later, mice were anesthetized with pentobarbital sodium (60 mg/kg), the left anterior descending coronary artery was ligated for 20 min, flow was restored for 2 h, and the resulting myocardial infarct (MI) size was evaluated. PM exposure doubled the relative size of the MI compared with the vehicle control. No difference was observed in the percentage of the left ventricle at risk for ischemia. PM exposure increased the level of oxidative stress in the myocardium after I/R. The density of neutrophils in the reperfused myocardium was increased by PM exposure, but differences in the number of blood leukocytes, expression of adhesion molecules on circulating neutrophils, and activation state of circulating neutrophils 24 h after PM exposure could not be correlated to the increased I/R injury observed. Additionally, aortas isolated from PM-exposed animals and studied in vitro exhibited a reduced endothelium-dependent relaxation response to acetylcholine. These results indicate that exposure to ultrafine PM increases oxidative stress in the myocardium, alters vascular reactivity, and augments injury after I/R in a murine model.
Collapse
Affiliation(s)
- Emily Cozzi
- Department of Physiology, Brody School of Medicine, East Carolina Univ., 6N98 Brody Bldg., Greenville, NC 27834, USA
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Patterson MF, Stephenson GMM, Stephenson DG. Denervation produces different single fiber phenotypes in fast- and slow-twitch hindlimb muscles of the rat. Am J Physiol Cell Physiol 2006; 291:C518-28. [PMID: 16611740 DOI: 10.1152/ajpcell.00013.2006] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using a single, mechanically skinned fiber approach, we tested the hypothesis that denervation (0 to 50 days) of skeletal muscles that do not overlap in fiber type composition [extensor digitorum longus (EDL) and soleus (SOL) muscles of Long-Evans hooded rats] leads to development of different fiber phenotypes. Denervation (50 day) was accompanied by 1) a marked increase in the proportion of hybrid IIB/D fibers (EDL) and I/IIA fibers (SOL) from 30% to >75% in both muscles, and a corresponding decrease in the proportion of pure fibers expressing only one myosin heavy chain (MHC) isoform; 2) complex muscle- and fiber-type specific changes in sarcoplasmic reticulum Ca(2+)-loading level at physiological pCa approximately 7.1, with EDL fibers displaying more consistent changes than SOL fibers; 3) decrease by approximately 50% in specific force of all fiber types; 4) decrease in sensitivity to Ca(2+), particularly for SOL fibers (by approximately 40%); 5) decrease in the maximum steepness of the force-pCa curves, particularly for the hybrid I/IIA SOL fibers (by approximately 35%); and 6) increased occurrence of biphasic behavior with respect to Sr(2+) activation in SOL fibers, indicating the presence of both slow and fast troponin C isoforms. No fiber types common to the two muscles were detected at any time points (day 7, 21, and 50) after denervation. The results provide strong evidence that not only neural factors, but also the intrinsic properties of a muscle fiber, influence the structural and functional properties of a particular muscle cell and explain important functional changes induced by denervation at both whole muscle and single cell levels.
Collapse
Affiliation(s)
- M F Patterson
- Department of Zoology, La Trobe University, Kingsbury Drive, Melbourne, Victoria 3086, Australia
| | | | | |
Collapse
|
20
|
Macdonald WA, Stephenson DG. Effect of ADP on slow-twitch muscle fibres of the rat: implications for muscle fatigue. J Physiol 2006; 573:187-98. [PMID: 16556653 PMCID: PMC1779704 DOI: 10.1113/jphysiol.2006.105775] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Slow-twitch mechanically skinned fibres from rat soleus muscle were bathed in solutions mimicking the myoplasmic environment but containing different [ADP] (0.1 microm to 1.0 mm). The effect of ADP on sarcoplasmic reticulum (SR) Ca2+-content was determined from the magnitude of caffeine-induced force responses, while temporal changes in SR Ca2+-content allowed determination of the effective rates of the SR Ca2+-pump and of the SR Ca2+-leak. The SR Ca2+-pump rate, estimated at pCa (-log10[Ca2+]) 7.8, was reduced by 20% as the [ADP] was increased from 0.1 to 40 microm, with no further alteration when the [ADP] was increased to 1.0 mm. The SR Ca2+-leak rate constant was not altered by increasing [ADP] from 0.1 to 40 microm, but was increased by 26% when the [ADP] was elevated to 1.0 mm. This ADP-induced SR Ca2+-leak was insensitive to ruthenium red but was abolished by 2,5-di(tert-butyl)-1,4-hydroquinone (TBQ), indicating that the leak pathway is via the SR Ca2+-pump and not the SR Ca2+-release channel. The decrease in SR Ca2+-pump rate and SR Ca2+-leak rate when [ADP] was increased led to a 40% decrease in SR Ca2+-loading capacity. Elevation of [ADP] had only minor direct effects on the contractile apparatus of slow-twitch fibres. These results suggest that ADP has only limited depressing effects on the contractility of slow-twitch muscle fibres. This is in contrast to the marked effects of ADP on force responses in fast-twitch muscle fibres and may contribute to the fatigue-resistant nature of slow-twitch muscle fibres.
Collapse
Affiliation(s)
- W A Macdonald
- Department of Zoology, La Trobe University, Bundoora, Victoria, 3083, Australia.
| | | |
Collapse
|
21
|
O'Connell B, Blazev R, Stephenson GMM. Electrophoretic and functional identification of two troponin C isoforms in toad skeletal muscle fibers. Am J Physiol Cell Physiol 2005; 290:C515-23. [PMID: 16176967 DOI: 10.1152/ajpcell.00307.2005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The differential sensitivity of frog twitch and slow-tonic fibers to Ca(2+) and Sr(2+) suggests that these two fiber types express different troponin C (TnC) isoforms. To date, only one TnC isoform from anurans (resembling the mammalian fast-twitch isoform) has been isolated and characterized. In this study, we examined the possibility that anuran striated muscle contains more than one TnC isoform. Toward this end, we determined the TnC isoform composition of 198 single fibers from the rectus abdominis of the cane toad (a mixed slow-tonic and twitch muscle) and of toad cardiac muscle using a method that enables the identification of TnC isoforms on the basis of the effect of Ca(2+) on their electrophoretic mobility. The fibers were typed according to their myosin heavy chain (MHC) isoform composition. The data indicate that striated muscle of the cane toad contains two TnC isoforms, one of which (TnC-t) is present in all fibers displaying only twitch MHC isoforms and the other of which (TnC-T/c) is present in fibers displaying the tonic MHC isoform and in cardiac muscle. For a subpopulation of 15 fibers, the TnC isoform composition was also compared with Ca(2+) and Sr(2+) activation characteristics. Fibers containing the TnC-T/c isoform were approximately 3-fold more sensitive to Ca(2+), approximately 40-fold more sensitive to Sr(2+), and responded to a approximately 4.6-fold broader range of [Ca(2+)] than did fibers containing the TnC-t isoform. The Ca(2+) activation properties of toad fibers containing the TnC-T/c isoform appear to be consistent with the previously reported physiological characteristics of amphibian slow-tonic muscle fibers.
Collapse
Affiliation(s)
- Brett O'Connell
- Muscle Cell Biochemistry Laboratory, School of Biomedical Sciences, Victoria Univ., PO Box 14428, MCMC, Melbourne, Victoria 8001, Australia
| | | | | |
Collapse
|
22
|
Jame DW, West JM, Dooley PC, Stephenson DG. Differential effects of arginine, glutamate and phosphoarginine on Ca(2+)-activation properties of muscle fibres from crayfish and rat. J Muscle Res Cell Motil 2005; 25:497-508. [PMID: 15711880 DOI: 10.1007/s10974-004-2769-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2003] [Accepted: 07/07/2004] [Indexed: 10/25/2022]
Abstract
The effects of two amino acids, arginine which has a positively charged side-chain and glutamate which has a negatively charged side-chain on the Ca2+-activation properties of the contractile apparatus were examined in four structurally and functionally different types of skeletal muscle; long- and short-sarcomere fibres from the claw muscle of the yabby (a freshwater decapod crustacean), and fast- and slow-twitch fibres from limb muscles of the rat. Single skinned fibres were activated in carefully balanced solutions of different pCa (-log10[Ca2+]) that either contained the test solute ("test") or not ("control"). The effect of phosphoarginine, a phosphagen that bears a nett negative charge, was also compared to the effects of arginine. Results show that (i) arginine (33-36 mmol l(-1)) significantly shifted the force-pCa curve by 0.08-0.13 pCa units in the direction of increased sensitivity to Ca2+-activated contraction in all fibre types; (ii) phosphoarginine (9-10 mmol l(-1)) induced a significant shift of the force-pCa curve by 0.18-0.24 pCa units in the direction of increased sensitivity to Ca2+ in mammalian fast- and slow-twitch fibres, but had no significant effects on the force-pCa relation in either long- or short-sarcomere crustacean fibres; (iii) glutamate (36-40 mmol l(-1)), like arginine affected the force-pCa relation of all fibre types investigated, but in the opposite direction, causing a significant decrease in the sensitivity to Ca2+-activated contraction by 0.08-0.19 pCa units; (iv) arginine, phosphoarginine and glutamate had little or no effect on the maximum Ca2+-activated force of crustacean and mammalian fibres. The results suggest that the opposing effects of glutamate and arginine are not related to simply their charge structure, but must involve complex interactions between these molecules, Ca2+ and the regulatory and other myofibrillar proteins.
Collapse
Affiliation(s)
- David W Jame
- Department of Zoology, La Trobe University, Victoria 3086, Australia.
| | | | | | | |
Collapse
|