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Rudolph TE, Roths M, Freestone AD, Yap SQ, Michael A, Rhoads RP, White-Springer SH, Baumgard LH, Selsby JT. Biological sex impacts oxidative stress in skeletal muscle in a porcine heat stress model. Am J Physiol Regul Integr Comp Physiol 2024; 326:R578-R587. [PMID: 38708546 PMCID: PMC11381024 DOI: 10.1152/ajpregu.00268.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/03/2024] [Accepted: 04/25/2024] [Indexed: 05/07/2024]
Abstract
Oxidative stress contributes to heat stress (HS)-mediated alterations in skeletal muscle; however, the extent to which biological sex mediates oxidative stress during HS remains unknown. We hypothesized muscle from males would be more resistant to oxidative stress caused by HS than muscle from females. To address this, male and female pigs were housed in thermoneutral conditions (TN; 20.8 ± 1.6°C; 62.0 ± 4.7% relative humidity; n = 8/sex) or subjected to HS (39.4 ± 0.6°C; 33.7 ± 6.3% relative humidity) for 1 (HS1; n = 8/sex) or 7 days (HS7; n = 8/sex) followed by collection of the oxidative portion of the semitendinosus. Although HS increased muscle temperature, by 7 days, muscle from heat-stressed females was cooler than muscle from heat-stressed males (0.3°C; P < 0.05). Relative protein abundance of 4-hydroxynonenal (4-HNE)-modified proteins increased in HS1 females compared with TN (P = 0.05). Furthermore, malondialdehyde (MDA)-modified proteins and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentration, a DNA damage marker, was increased in HS7 females compared with TN females (P = 0.05). Enzymatic activities of catalase and superoxide dismutase (SOD) remained similar between groups; however, glutathione peroxidase (GPX) activity decreased in HS7 females compared with TN and HS1 females (P ≤ 0.03) and HS7 males (P = 0.02). Notably, HS increased skeletal muscle Ca2+ deposition (P = 0.05) and was greater in HS1 females compared with TN females (P < 0.05). Heat stress increased sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA)2a protein abundance (P < 0.01); however, Ca2+ ATPase activity remained similar between groups. Overall, despite having lower muscle temperature, muscle from heat-stressed females had increased markers of oxidative stress and calcium deposition than muscle from males following identical environmental exposure.NEW & NOTEWORTHY Heat stress is a global threat to human health and agricultural production. We demonstrated that following 7 days of heat stress, skeletal muscle from females was more susceptible to oxidative stress than muscle from males in a porcine model, despite cooler muscle temperatures. The vulnerability to heat stress-induced oxidative stress in females may be driven, at least in part, by decreased antioxidant capacity and calcium dysregulation.
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Affiliation(s)
- Tori E Rudolph
- Department of Animal Science, Iowa State University, Ames, Iowa, United States
| | - Melissa Roths
- Department of Animal Science, Iowa State University, Ames, Iowa, United States
| | - Alyssa D Freestone
- Department of Animal Science, Iowa State University, Ames, Iowa, United States
| | - Sau Qwan Yap
- Department of Animal Science, Iowa State University, Ames, Iowa, United States
| | - Alyona Michael
- Department of Vet Diagnostic & Production Animal Med, Iowa State University, Ames, Iowa, United States
| | - Robert P Rhoads
- School of Animal Sciences, Virginia Tech, Blacksburg, Virginia, United States
| | - Sarah H White-Springer
- Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, Texas, United States
- Department of Kinesiology and Sport Management, Texas A&M University, College Station, Texas, United States
| | - Lance H Baumgard
- Department of Animal Science, Iowa State University, Ames, Iowa, United States
| | - Joshua T Selsby
- Department of Animal Science, Iowa State University, Ames, Iowa, United States
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2
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Périard JD, Eijsvogels TMH, Daanen HAM. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiol Rev 2021; 101:1873-1979. [PMID: 33829868 DOI: 10.1152/physrev.00038.2020] [Citation(s) in RCA: 149] [Impact Index Per Article: 49.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.
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Affiliation(s)
- Julien D Périard
- University of Canberra Research Institute for Sport and Exercise, Bruce, Australia
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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3
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Mornas A, Racinais S, Brocherie F, Alhammoud M, Hager R, Desmedt Y, Guilhem G. Hyperthermia reduces electromechanical delay via accelerated electrochemical processes. J Appl Physiol (1985) 2021; 130:290-297. [PMID: 33180642 DOI: 10.1152/japplphysiol.00538.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study aimed to determine the effect of hyperthermia on both electrochemical and mechanical components of the electromechanical delay (EMD), using very-high-frame-rate ultrasound. Electrically evoked peak twitch force, EMD, electrochemical (Dm; i.e., delay between stimulation and muscle fascicle motion), and mechanical (Tm; i.e., delay between fascicle motion and force production onset) components of EMD were assessed in 16 participants. Assessments were conducted in a control ambient environment (CON; 26°C, 34% relative humidity) and in a hot ambient environment (HOT; 46-50°C, 18% relative humidity, after ∼127 min of heat exposure). Following heat exposure, gastrocnemius medialis temperature was 37.0 ± 0.6°C in HOT vs. 34.0 ± 0.8°C in CON (P < 0.001). EMD was shorter (9.4 ± 0.8 ms) in HOT than in CON (10.8 ± 0.6 ms, P < 0.001). Electrochemical processes were shorter in HOT than in CON (4.0 ± 0.8 ms vs. 5.5 ± 0.9 ms, respectively, P < 0.001), whereas mechanical processes were unchanged (P = 0.622). These results demonstrate that hyperthermia reduces electromechanical delay via accelerated electrochemical processes, whereas force transmission along the active and passive parts of the series elastic component is not affected following heat exposure. The present study demonstrates that heat exposure accelerates muscle contraction thanks to faster electrochemical processes. Further investigations during voluntary contractions would contribute to better understand how these findings translate into motor performance.NEW & NOTEWORTHY Hyperthermia (targeted core temperature: 38.5°C) reduces the time between gastrocnemius medialis stimulation and the onset of plantar flexor force production in vivo. This reduction in electromechanical delay is concomitant to an earlier motion of muscle fascicle compared with thermoneutral environment. However, hyperthermia has no impact on the duration of force transmission along aponeurosis and tendon, thereby reflecting different effects of heat exposure on contractile and elastic properties of the muscle-tendon unit.
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Affiliation(s)
- Adèle Mornas
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance, Paris, France.,Université de Paris, Paris, France
| | - Sébastien Racinais
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance, Paris, France.,Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar
| | - Franck Brocherie
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance, Paris, France
| | - Marine Alhammoud
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar
| | - Robin Hager
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance, Paris, France
| | - Yanis Desmedt
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance, Paris, France
| | - Gaël Guilhem
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance, Paris, France
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4
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McCormick JJ, Dokladny K, Moseley PL, Kenny GP. Autophagy and heat: a potential role for heat therapy to improve autophagic function in health and disease. J Appl Physiol (1985) 2021; 130:1-9. [DOI: 10.1152/japplphysiol.00542.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Autophagy is a crucial cell survival mechanism that involves the degradation and recycling of old or damaged organelles and proteins to maintain cellular homeostasis. Impairments in autophagy are central to the pathogenesis of many conditions including metabolic and neurodegenerative disorders, cardiovascular and pulmonary diseases, diabetes, and aging. Although various pharmacological agents may be able to stimulate autophagic function, to our knowledge, few interventions exist that have been deemed safe and effective in humans. An emerging body of evidence suggests that targeting the autophagic pathway via passive heating (heat therapy) may stimulate autophagic function. Therefore, the primary focus of the present review is to analyze the mechanisms in which passive heating induces autophagy as defined by in vitro and in vivo (animal and human) models. Our secondary focus is to examine the implications of utilizing passive heating to restore dysfunctional autophagy in chronic disease and aging. Finally, we discuss potential therapeutic strategies to implement passive heating to stimulate autophagic function in humans.
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Affiliation(s)
- James J. McCormick
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Karol Dokladny
- Department of Internal Medicine, The University of New Mexico, Albuquerque, New Mexico
| | - Pope L. Moseley
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
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5
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Phospholamban and sarcolipin prevent thermal inactivation of sarco(endo)plasmic reticulum Ca2+-ATPases. Biochem J 2020; 477:4281-4294. [PMID: 33111944 DOI: 10.1042/bcj20200346] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 10/15/2020] [Accepted: 10/28/2020] [Indexed: 12/31/2022]
Abstract
Na+-K+-ATPase from mice lacking the γ subunit exhibits decreased thermal stability. Phospholamban (PLN) and sarcolipin (SLN) are small homologous proteins that regulate sarco(endo)plasmic reticulum Ca2+-ATPases (SERCAs) with properties similar to the γ subunit, through physical interactions with SERCAs. Here, we tested the hypothesis that PLN and SLN may protect against thermal inactivation of SERCAs. HEK-293 cells were co-transfected with different combinations of cDNAs encoding SERCA2a, PLN, a PLN mutant (N34A) that cannot bind to SERCA2a, and SLN. One-half of the cells were heat stressed at 40°C for 1 h (HS), and one-half were maintained at 37°C (CTL) before harvesting the cells and isolating microsomes. Compared with CTL, maximal SERCA activity was reduced by 25-35% following HS in cells that expressed either SERCA2a alone or SERCA2a and mutant PLN (N34A) whereas no change in maximal SERCA2a activity was observed in cells that co-expressed SERCA2a and either PLN or SLN following HS. Increases in SERCA2a carbonyl group content and nitrotyrosine levels that were detected following HS in cells that expressed SERCA2a alone were prevented in cells co-expressing SERCA2a with PLN or SLN, whereas co-expression of SERCA2a with mutant PLN (N34A) only prevented carbonyl group formation. In other experiments using knock-out mice, we found that thermal inactivation of SERCA was increased in cardiac left ventricle samples from Pln-null mice and in diaphragm samples from Sln-null mice, compared with WT littermates. Our results show that both PLN and SLN form a protective interaction with SERCA pumps during HS, preventing nitrosylation and oxidation of SERCA and thus preserving its maximal activity.
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6
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Racinais S, Cocking S, Périard JD. Sports and environmental temperature: From warming-up to heating-up. Temperature (Austin) 2017; 4:227-257. [PMID: 28944269 DOI: 10.1080/23328940.2017.1356427] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/09/2017] [Accepted: 07/09/2017] [Indexed: 01/22/2023] Open
Abstract
Most professional and recreational athletes perform pre-conditioning exercises, often collectively termed a 'warm-up' to prepare for a competitive task. The main objective of warming-up is to induce both temperature and non-temperature related responses to optimize performance. These responses include increasing muscle temperature, initiating metabolic and circulatory adjustments, and preparing psychologically for the upcoming task. However, warming-up in hot and/or humid ambient conditions increases thermal and circulatory strain. As a result, this may precipitate neuromuscular and cardiovascular impairments limiting endurance capacity. Preparations for competing in the heat should include an acclimatization regimen. Athletes should also consider cooling interventions to curtail heat gain during the warm-up and minimize dehydration. Indeed, although it forms an important part of the pre-competition preparation in all environmental conditions, the rise in whole-body temperature should be limited in hot environments. This review provides recommendations on how to build an effective warm-up following a 3 stage RAMP model (Raise, Activate and Mobilize, Potentiate), including general and context specific exercises, along with dynamic flexibility work. In addition, this review provides suggestion to manipulate the warm-up to suit the demands of competition in hot environments, along with other strategies to avoid heating-up.
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Affiliation(s)
- Sébastien Racinais
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, France
| | - Scott Cocking
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,Research Institute for Sport and Exercise Science, Liverpool John Moores University, United Kingdom
| | - Julien D Périard
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,University of Canberra, Research Institute for Sport and Exercise, Canberra, Australia
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7
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Heat-Induced Calcium Leakage Causes Mitochondrial Damage in Caenorhabditis elegans Body-Wall Muscles. Genetics 2017; 206:1985-1994. [PMID: 28576866 PMCID: PMC5560802 DOI: 10.1534/genetics.117.202747] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 05/23/2017] [Indexed: 01/22/2023] Open
Abstract
Acute onset of organ failure in heatstroke is triggered by rhabdomyolysis of skeletal muscle. Here, we showed that elevated temperature increases free cytosolic Ca2+ [Ca2+]f from RYR (ryanodine receptor)/UNC-68in vivo in the muscles of an experimental model animal, the nematode Caenorhabditis elegans. This subsequently leads to mitochondrial fragmentation and dysfunction, and breakdown of myofilaments similar to rhabdomyolysis. In addition, treatment with an inhibitor of RYR (dantrolene) or activation of FoxO (Forkhead box O)/DAF-16 is effective against heat-induced muscle damage. Acute onset of organ failure in heatstroke is triggered by rhabdomyolysis of skeletal muscle. To gain insight into heat-induced muscle breakdown, we investigated alterations of Ca2+ homeostasis and mitochondrial morphology in vivo in body-wall muscles of C. elegans exposed to elevated temperature. Heat stress for 3 hr at 35° increased the concentration of [Ca2+]f, and led to mitochondrial fragmentation and subsequent dysfunction in the muscle cells. A similar mitochondrial fragmentation phenotype is induced in the absence of heat stress by treatment with a calcium ionophore, ionomycin. Mutation of the unc-68 gene, which encodes the ryanodine receptor that is linked to Ca2+ release from the sarcoplasmic reticulum, could suppress the mitochondrial dysfunction, muscle degeneration, and reduced mobility and life span induced by heat stress. In addition, in a daf-2 mutant, in which the DAF-16/FoxO transcription factor is activated, resistance to calcium overload, mitochondrial fragmentation, and dysfunction was observed. These findings reveal that heat-induced Ca2+ accumulation causes mitochondrial damage and consequently induces muscle breakdown.
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8
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Ganesan S, Reynolds C, Hollinger K, Pearce SC, Gabler NK, Baumgard LH, Rhoads RP, Selsby JT. Twelve hours of heat stress induces inflammatory signaling in porcine skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1288-96. [PMID: 27009052 DOI: 10.1152/ajpregu.00494.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/21/2016] [Indexed: 01/08/2023]
Abstract
Heat stress causes morbidity and mortality in humans and animals and threatens food security by limiting livestock productivity. Inflammatory signaling may contribute to heat stress-mediated skeletal muscle dysfunction. Previously, we discovered increased circulating endotoxin and intramuscular oxidative stress and TNF-α protein abundance, but not inflammatory signaling following 24 and 72 h of heat stress. Thus the purpose of this investigation was to clarify the role of inflammatory signaling in heat-stressed skeletal muscle. Crossbred gilts (n = 8/group) were assigned to either thermal neutral (24°C), heat stress (37°C), or pair-fed thermal neutral (24°C) conditions for 12 h. Following treatment, animals were euthanized, and the semitendinosus red (STR) and white (STW) were recovered. Heat stress did not alter inflammatory signaling in STW. In STR, relative heat shock protein abundance was similar between groups, as was nuclear content of heat shock factor 1. In whole homogenate, relative abundance of the NF-κB activator inhibitory κB kinase-α was increased by heat stress, although abundance of NF-κB was similar between groups. Relative abundance of phosphorylated NF-κB was increased by heat stress in nuclear fractions. Activator protein-1 (AP-1) signaling was similar between groups. While there were few differences in transcript expression between thermal neutral and heat stress, 80 and 56% of measured transcripts driven by NF-κB or AP-1, respectively, were increased by heat stress compared with pair-fed thermal neutral. Heat stress also caused a reduction in IL-6 transcript and relative protein abundance. These data demonstrate that short-term heat stress causes inflammatory signaling through NF-κB in oxidative, but not glycolytic, skeletal muscle.
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Affiliation(s)
- Shanthi Ganesan
- Department of Animal Science, Iowa State University, Ames, Iowa; and
| | - Carmen Reynolds
- Department of Animal Science, Iowa State University, Ames, Iowa; and
| | - Katrin Hollinger
- Department of Animal Science, Iowa State University, Ames, Iowa; and
| | - Sarah C Pearce
- Department of Animal Science, Iowa State University, Ames, Iowa; and
| | - Nicholas K Gabler
- Department of Animal Science, Iowa State University, Ames, Iowa; and
| | - Lance H Baumgard
- Department of Animal Science, Iowa State University, Ames, Iowa; and
| | - Robert P Rhoads
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - Joshua T Selsby
- Department of Animal Science, Iowa State University, Ames, Iowa; and
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9
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Montilla SIR, Johnson TP, Pearce SC, Gardan-Salmon D, Gabler NK, Ross JW, Rhoads RP, Baumgard LH, Lonergan SM, Selsby JT. Heat stress causes oxidative stress but not inflammatory signaling in porcine skeletal muscle. Temperature (Austin) 2014; 1:42-50. [PMID: 27583280 PMCID: PMC4972518 DOI: 10.4161/temp.28844] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 04/08/2014] [Accepted: 04/08/2014] [Indexed: 02/07/2023] Open
Abstract
Heat stress is associated with death and other maladaptions including muscle dysfunction and impaired growth across species. Despite this common observation, the molecular effects leading to these pathologic changes remain unclear. The purpose of this study was to determine the extent to which heat stress disrupted redox balance and initiated an inflammatory response in oxidative and glycolytic skeletal muscle. Female pigs (5-6/group) were subjected to thermoneutral (20 °C) or heat stress (35 °C) conditions for 1 or 3 days and the semitendinosus removed and dissected into red (STR) and white (STW) portions. After 1 day of heat stress, relative abundance of proteins modified by malondialdehyde, a measure of oxidative damage, was increased 2.5-fold (P < 0.05) compared with thermoneutral in the STR but not the STW, before returning to thermoneutral conditions following 3 days of heat stress. This corresponded with increased catalase and superoxide dismutase-1 gene expression (P < 0.05) and superoxide dismutase-1 protein abundance (P < 0.05) in the STR but not the STW. In the STR catalase and total superoxide dismutase activity were increased by ~30% and ~130%, respectively (P < 0.05), after 1 day of heat stress and returned to thermoneutral levels by day 3. One or 3 days of heat stress did not increase inflammatory signaling through the NF-κB pathway in the STR or STW. These data suggest that oxidative muscle is more susceptible to heat stress-mediated changes in redox balance than glycolytic muscle during chronic heat stress.
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Affiliation(s)
| | | | - Sarah C Pearce
- Department of Animal Science; Iowa State University; Ames, IA USA
| | | | | | - Jason W Ross
- Department of Animal Science; Iowa State University; Ames, IA USA
| | - Robert P Rhoads
- Department of Animal and Poultry Sciences; Virginia Tech; Blacksburg, VA USA
| | - Lance H Baumgard
- Department of Animal Science; Iowa State University; Ames, IA USA
| | | | - Joshua T Selsby
- Department of Animal Science; Iowa State University; Ames, IA USA
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10
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Fluorescence Imaging of Calcium Loading and Mitochondrial Depolarization in Cancer Cells Exposed to Heat Stress. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/978-1-4419-1260-2_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
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11
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Tupling AR, Bombardier E, Vigna C, Quadrilatero J, Fu M. Interaction between Hsp70 and the SR Ca2+pump: a potential mechanism for cytoprotection in heart and skeletal muscle. Appl Physiol Nutr Metab 2008; 33:1023-32. [DOI: 10.1139/h08-067] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The overexpression of heat shock protein 70 (Hsp70) provides cytoprotection to cells, making them resistant to otherwise lethal levels of stress. In this review, the role Hsp70 plays in protecting both cardiac and skeletal muscle against the pathophysiological effects of oxidative stress are examined, with a focus on the molecular basis for the cytoprotective effects of Hsp70. The ability of Hsp70 to maintain cell survival undoubtedly involves the regulation of multiple steps within apoptotic pathways, but could also involve the regulation of key upstream mediators of apoptosis (i.e., oxidative stress, Ca2+overload). Hsp70 can stabilize the structure and function of both the skeletal muscle and cardiac Ca2+pump under heat stress conditions. Given that Ca2+overload has long been implicated in cell death, Hsp70 might protect muscle cells by maintaining cellular Ca2+homeostasis, thereby preventing the initiation of apoptosis. The functional interaction between Hsp70 and Ca2+pumps might also promote improvements in muscle contractility after exposure to oxidative stress.
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Affiliation(s)
- A. Russell Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Eric Bombardier
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Chris Vigna
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Joe Quadrilatero
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Minghua Fu
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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12
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Oliver SR, Wright VP, Parinandi N, Clanton TL. Thermal tolerance of contractile function in oxidative skeletal muscle: no protection by antioxidants and reduced tolerance with eicosanoid enzyme inhibition. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1695-705. [PMID: 18768765 DOI: 10.1152/ajpregu.90429.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mechanisms for the loss of muscle contractile function in hyperthermia are poorly understood. This study identified the critical temperature, resulting in a loss of contractile function in isolated diaphragm (thermal tolerance), and then tested the hypotheses 1) that increased reactive oxygen species (ROS) production contributes to the loss of contractile function at this temperature, and 2) eicosanoid metabolism plays an important role in preservation of contractile function in hyperthermia. Contractile function and passive force were measured in rat diaphragm bundles during and after 30 min of exposure to 40, 41, 42 or 43 degrees C. Between 40 and 42 degrees C, there were no effects of hyperthermia, but at 43 degrees C, a significant loss of active force and an increase in passive force were observed. Inhibition of ROS with the antioxidants, Tiron or Trolox, did not inhibit the loss of contractile force at 43 degrees C. Furthermore, treatment with dithiothreitol, a thiol (-SH) reducing agent, did not reverse the effects of hyperthermia. A variety of global lipoxygenase (LOX) inhibitors further depressed force during 43 degrees C and caused a significant loss of thermal tolerance at 42 degrees C. Cyclooxygenase (COX) inhibitors also caused a loss of thermal tolerance at 42 degrees C. Blockage of phospholipase with phospholipase A(2) inhibitors, bromoenol lactone or arachidonyltrifluoromethyl ketone failed to significantly prevent the loss of force at 43 degrees C. Overall, these data suggest that ROS do not play an apparent role in the loss of contractile function during severe hyperthermia in diaphragm. However, functional LOX and COX enzyme activities appear to be necessary for maintaining normal force production in hyperthermia.
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Affiliation(s)
- S Ryan Oliver
- University of Florida, Department of Applied Physiology and Kinesiology, Gainesville, Florida 32611, USA
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13
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Chen W, Ruell PA, Ghoddusi M, Kee A, Hardeman EC, Hoffman KM, Thompson MW. Ultrastructural changes and sarcoplasmic reticulum Ca2+ regulation in red vastus muscle following eccentric exercise in the rat. Exp Physiol 2006; 92:437-47. [PMID: 17138618 DOI: 10.1113/expphysiol.2006.036442] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study examined the effects of a bout of low-intensity, prolonged downhill exercise on sarcoplasmic reticulum (SR) Ca(2+)-ATPase activity, Ca(2+) uptake and release in rat red vastus muscle. Ionophore stimulation was determined to assess vesicle integrity by measuring the ratio of Ca(2+)-ATPase activities in the presence and absence of A23187. Observations of the muscle ultrastructure were made to evaluate muscle damage at the level of the myofibrils and SR. Adult male Sprague-Dawley rats (weight, 395 +/- 5.9 g) were either assigned as non-exercise controls or subjected to 90 min of downhill treadmill exercise (-16 deg; 15 m min(-1)), and then killed immediately, 4, 24, 48, 72 or 144 h after exercise (n = 7). Calcium uptake was significantly lower (P < 0.05) compared with control values (19.25 +/- 1.38 nmol min(-1) (mg protein)(-1)), by 29 and 36% immediately and 4 h postexercise, respectively, and remained depressed (P < 0.05) 24 h postexercise. Calcium release was also significantly lower (P < 0.05) compared with control values (31.06 +/- 2.36 nmol min(-1) (mg protein)(-1)), by 37 and 39% immediately and 4 h postexercise, respectively, and remained depressed (P < 0.05) 24 h postexercise. Ca(2+)-ATPase activity measured with ionophore was 31% lower (P < 0.05) 4 h postexercise, and remained lower (P < 0.05) 24 h postexercise. The ratio of Ca(2+)-ATPase activities in the presence and absence of A23187 was not significantly changed after exercise, indicating that membrane integrity was not altered by the exercise. Focal dilatations of the SR were observed immediately and 4 h following exercise, implying that SR may be susceptible to damage in the localized regions of overstretched sarcomeres. The results demonstrate that a bout of low-intensity, prolonged downhill exercise results in a long-lasting depression of SR function that is not fully restored after 2 days of recovery, which may underlie some functional impairments induced by eccentric exercise.
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Affiliation(s)
- Wan Chen
- School of Exercise & Sport Science, The University of Sydney, Sydney, NSW 1825, Australia
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