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Garrett EJ, Prasad SK, Schweizer RM, McClelland GB, Scott GR. Evolved changes in phenotype across skeletal muscles in deer mice native to high altitude. Am J Physiol Regul Integr Comp Physiol 2024; 326:R297-R310. [PMID: 38372126 DOI: 10.1152/ajpregu.00206.2023] [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: 08/24/2023] [Revised: 01/11/2024] [Accepted: 02/09/2024] [Indexed: 02/20/2024]
Abstract
The cold and hypoxic conditions at high altitude necessitate high metabolic O2 demands to support thermogenesis while hypoxia reduces O2 availability. Skeletal muscles play key roles in thermogenesis, but our appreciation of muscle plasticity and adaptation at high altitude has been hindered by past emphasis on only a small number of muscles. We examined this issue in deer mice (Peromyscus maniculatus). Mice derived from both high-altitude and low-altitude populations were born and raised in captivity and then acclimated as adults to normoxia or hypobaric hypoxia (12 kPa O2 for 6-8 wk). Maximal activities of citrate synthase (CS), cytochrome c oxidase (COX), β-hydroxyacyl-CoA dehydrogenase (HOAD), hexokinase (HK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) were measured in 20 muscles involved in shivering, locomotion, body posture, ventilation, and mastication. Principal components analysis revealed an overall difference in muscle phenotype between populations but no effect of hypoxia acclimation. High-altitude mice had greater activities of mitochondrial enzymes and/or lower activities of PK or LDH across many (but not all) respiratory, limb, core and mastication muscles compared with low-altitude mice. In contrast, chronic hypoxia had very few effects across muscles. Further examination of CS in the gastrocnemius showed that population differences in enzyme activity stemmed from differences in protein abundance and mRNA expression but not from population differences in CS amino acid sequence. Overall, our results suggest that evolved increases in oxidative capacity across many skeletal muscles, at least partially driven by differences in transcriptional regulation, may contribute to high-altitude adaptation in deer mice.NEW & NOTEWORTHY Most previous studies of muscle plasticity and adaptation in high-altitude environments have focused on a very limited number of skeletal muscles. Comparing high-altitude versus low-altitude populations of deer mice, we show that a large number of muscles involved in shivering, locomotion, body posture, ventilation, and mastication exhibit greater mitochondrial enzyme activities in the high-altitude population. Therefore, evolved increases in mitochondrial oxidative capacity across skeletal muscles contribute to high-altitude adaptation.
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Affiliation(s)
- Emily J Garrett
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Srikripa K Prasad
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Rena M Schweizer
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States
- United States Department of Agriculture, Agricultural Research Service, Pollinating Insects Research Unit, Utah State University, Logan, Utah, United States
| | | | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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2
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Thoral E, Dargère L, Medina-Suárez I, Clair A, Averty L, Sigaud J, Morales A, Salin K, Teulier L. Non-lethal sampling for assessment of mitochondrial function does not affect metabolic rate and swimming performance. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220483. [PMID: 38186271 PMCID: PMC10772603 DOI: 10.1098/rstb.2022.0483] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 09/26/2023] [Indexed: 01/09/2024] Open
Abstract
A fundamental issue in the metabolic field is whether it is possible to understand underlying mechanisms that characterize individual variation. Whole-animal performance relies on mitochondrial function as it produces energy for cellular processes. However, our lack of longitudinal measures to evaluate how mitochondrial function can change within and among individuals and with environmental context makes it difficult to assess individual variation in mitochondrial traits. The aims of this study were to test the repeatability of muscle mitochondrial metabolism by performing two biopsies of red muscle, and to evaluate the effects of biopsies on whole-animal performance in goldfish Carassius auratus. Our results show that basal mitochondrial respiration and net phosphorylation efficiency are repeatable at 14-day intervals. We also show that swimming performance (optimal cost of transport and critical swimming speed) was repeatable in biopsied fish, whereas the repeatability of individual oxygen consumption (standard and maximal metabolic rates) seemed unstable over time. However, we noted that the means of individual and mitochondrial traits did not change over time in biopsied fish. This study shows that muscle biopsies allow the measurement of mitochondrial metabolism without sacrificing animals and that two muscle biopsies 14 days apart affect the intraspecific variation in fish performance without affecting average performance of individuals. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'.
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Affiliation(s)
- Elisa Thoral
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
- Department of Biology, Section for Evolutionary Ecology, Lund University, Sölvegatan 37, Lund 223 62, Sweden
| | - Lauréliane Dargère
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Ione Medina-Suárez
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, Unidad Asociada ULPGC-CSIC, Campus de Taliarte, 35214 Telde, Gran Canaria, Canary Islands, Spain
| | - Angéline Clair
- Plateforme Animalerie Conventionnelle et Sauvage Expérimentale de la Doua (ACSED), Fédération de Recherche 3728, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENS-Lyon, INRAE, INSA, VetAgroSup 69622, Villeurbanne, France
| | - Laetitia Averty
- Plateforme Animalerie Conventionnelle et Sauvage Expérimentale de la Doua (ACSED), Fédération de Recherche 3728, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENS-Lyon, INRAE, INSA, VetAgroSup 69622, Villeurbanne, France
| | - Justine Sigaud
- Plateforme Animalerie Conventionnelle et Sauvage Expérimentale de la Doua (ACSED), Fédération de Recherche 3728, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENS-Lyon, INRAE, INSA, VetAgroSup 69622, Villeurbanne, France
| | - Anne Morales
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Karine Salin
- Ifremer, CNRS, RD, Laboratory of Environmental Marine Sciences, Université de Brest, 29280 Plouzané, France
| | - Loïc Teulier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
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Schytz CT, Ørtenblad N, Lundby AKM, Jacobs RA, Nielsen J, Lundby C. Skeletal muscle mitochondria demonstrate similar respiration per cristae surface area independent of training status and sex in healthy humans. J Physiol 2024; 602:129-151. [PMID: 38051639 DOI: 10.1113/jp285091] [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: 05/31/2023] [Accepted: 11/15/2023] [Indexed: 12/07/2023] Open
Abstract
The impact of training status and sex on intrinsic skeletal muscle mitochondrial respiratory capacity remains unclear. We examined this by analysing human skeletal muscle mitochondrial respiration relative to mitochondrial volume and cristae density across training statuses and sexes. Mitochondrial cristae density was estimated in skeletal muscle biopsies originating from previous independent studies. Participants included females (n = 12) and males (n = 41) across training statuses ranging from untrained (UT, n = 8), recreationally active (RA, n = 9), active-to-elite runners (RUN, n = 27) and cross-country skiers (XC, n = 9). The XC and RUN groups demonstrated higher mitochondrial volume density than the RA and UT groups while all active groups (RA, RUN and XC) displayed higher mass-specific capacity of oxidative phosphorylation (OXPHOS) and mitochondrial cristae density than UT. Differences in OXPHOS diminished between active groups and UT when normalising to mitochondrial volume density and were lost when normalising to muscle cristae surface area density. Moreover, active females (n = 6-9) and males (n = 15-18) did not differ in mitochondrial volume and cristae density, OXPHOS, or when normalising OXPHOS to mitochondrial volume density and muscle cristae surface area density. These findings demonstrate: (1) differences in OXPHOS between active and untrained individuals may be explained by both higher mitochondrial volume and cristae density in active individuals, with no difference in intrinsic mitochondrial respiratory capacity (OXPHOS per muscle cristae surface area density); and (2) no sex differences in mitochondrial volume and cristae density or mass-specific and normalised OXPHOS. This highlights the importance of normalising OXPHOS to muscle cristae surface area density when studying skeletal muscle mitochondrial biology. KEY POINTS: Oxidative phosphorylation is the mitochondrial process by which ATP is produced, governed by the electrochemical gradient across the inner mitochondrial membrane with infoldings named cristae. In human skeletal muscle, the mass-specific capacity of oxidative phosphorylation (OXPHOS) can change independently of shifts in mitochondrial volume density, which may be attributed to variations in cristae density. We demonstrate that differences in skeletal muscle OXPHOS between healthy females and males, ranging from untrained to elite endurance athletes, are matched by differences in cristae density. This suggests that higher OXPHOS in skeletal muscles of active individuals is attributable to an increase in the density of cristae. These findings broaden our understanding of the variability in human skeletal muscle OXPHOS and highlight the significance of cristae, specific to mitochondrial respiration.
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Affiliation(s)
- Camilla Tvede Schytz
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Anne-Kristine Meinild Lundby
- Xlab, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Robert Acton Jacobs
- Department of Human Physiology & Nutrition, University of Colorado Colorado Springs (UCCS), Colorado Springs, Colorado, USA
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Carsten Lundby
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
- Department of Health and Exercise Physiology, Inland Norway University of Applied Science, Lillehammer, Norway
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Nybo L, Rønnestad B, Lundby C. High or hot-Perspectives on altitude camps and heat-acclimation training as preparation for prolonged stage races. Scand J Med Sci Sports 2024; 34:e14268. [PMID: 36350277 DOI: 10.1111/sms.14268] [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] [Received: 09/02/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022]
Abstract
Adaptation to heat stress and hypoxia are relevant for athletes participating in Tour de France or similar cycling races taking place during the summertime in landscapes with varying altitude. Both to minimize detrimental performance effects associated with arterial desaturation occurring at moderate altitudes in elite athletes, respectively, reduce the risk of hyperthermia on hot days, but also as a pre-competition acclimatization strategy to boost blood volume in already highly adapted athletes. The hematological adaptations require weeks of exposure to manifest, but are attractive as an augmented hemoglobin mass may improve arterial oxygen delivery and hence benefit prolonged performances. Altitude training camps have in this context a long history in exercise physiology and are still common practice in elite cycling. However, heat-acclimation training provides an attractive alternative for some athletes either as a stand-alone approach or in combination with altitude. The present paper provides an update and practical perspectives on the potential to utilize hypoxia and heat exposure to optimize hematological adaptations. Furthermore, we will consider temporal aspects both in terms of onset and decay of the adaptations relevant for improved thermoregulatory capacity and respiratory adaptations to abate arterial desaturation during altitude exposure. From focus on involved physiological mechanisms, time course, and responsiveness in elite athletes, we will provide guidance based on our experience from practical implementation in cyclists preparing for prolonged stage races such as the Tour de France.
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Affiliation(s)
- Lars Nybo
- Department of Nutrition, Exercise and Sport, University of Copenhagen, Copenhagen, Denmark
| | - Bent Rønnestad
- Inland Norway University of Applied Sciences, Lillehammer, Norway
| | - Carsten Lundby
- Inland Norway University of Applied Sciences, Lillehammer, Norway
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Bourdillon N, Subudhi AW, Fan JL, Evero O, Elliott JE, Lovering AT, Roach RC, Kayser B. AltitudeOmics: effects of 16 days acclimatization to hypobaric hypoxia on muscle oxygen extraction during incremental exercise. J Appl Physiol (1985) 2023; 135:823-832. [PMID: 37589059 PMCID: PMC10642515 DOI: 10.1152/japplphysiol.00100.2023] [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: 02/16/2023] [Revised: 07/11/2023] [Accepted: 08/03/2023] [Indexed: 08/18/2023] Open
Abstract
Acute altitude exposure lowers arterial oxygen content ([Formula: see text]) and cardiac output ([Formula: see text]) at peak exercise, whereas O2 extraction from blood to working muscles remains similar. Acclimatization normalizes [Formula: see text] but not peak [Formula: see text] nor peak oxygen consumption (V̇o2peak). To what extent acclimatization impacts muscle O2 extraction remains unresolved. Twenty-one sea-level residents performed an incremental cycling exercise to exhaustion near sea level (SL), in acute (ALT1) and chronic (ALT16) hypoxia (5,260 m). Arterial blood gases, gas exchange at the mouth and oxy- (O2Hb) and deoxyhemoglobin (HHb) of the vastus lateralis were recorded to assess arterial O2 content ([Formula: see text]), [Formula: see text], and V̇o2. The HHb-V̇o2 slope was taken as a surrogate for muscle O2 extraction. During moderate-intensity exercise, HHb-V̇o2 slope increased to a comparable extent at ALT1 (2.13 ± 0.94) and ALT16 (2.03 ± 0.88) compared with SL (1.27 ± 0.12), indicating increased O2 extraction. However, the HHb/[Formula: see text] ratio increased from SL to ALT1 and then tended to go back to SL values at ALT16. During high-intensity exercise, HHb-V̇o2 slope reached a break point beyond which it decreased at SL and ALT1, but not at ALT16. Increased muscle O2 extraction during submaximal exercise was associated with decreased [Formula: see text] in acute hypoxia. The significantly greater muscle O2 extraction during maximal exercise in chronic hypoxia is suggestive of an O2 reserve.NEW & NOTEWORTHY During incremental exercise muscle deoxyhemoglobin (HHb) and oxygen consumption (V̇o2) both increase linearly, and the slope of their relationship is an indirect index of local muscle O2 extraction. The latter was assessed at sea level, in acute and during chronic exposure to 5,260 m. The demonstrated presence of a muscle O2 extraction reserve during chronic exposure is coherent with previous studies indicating both limited muscle oxidative capacity and decrease in motor drive.
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Affiliation(s)
- Nicolas Bourdillon
- Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland
| | - Andrew W Subudhi
- Hybl Sports Medicine and Performance Center, Department of Human Physiology and Nutrition, University of Colorado, Colorado Springs, Colorado, United States
| | - Jui-Lin Fan
- Department of Physiology, Faculty of Medical & Health Sciences, Manaaki Manawa-The Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Oghenero Evero
- Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Jonathan E Elliott
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States
| | - Robert C Roach
- Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Bengt Kayser
- Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland
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6
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Adar O, Hollander A, Ilan Y. The Constrained Disorder Principle Accounts for the Variability That Characterizes Breathing: A Method for Treating Chronic Respiratory Diseases and Improving Mechanical Ventilation. Adv Respir Med 2023; 91:350-367. [PMID: 37736974 PMCID: PMC10514877 DOI: 10.3390/arm91050028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/23/2023]
Abstract
Variability characterizes breathing, cellular respiration, and the underlying quantum effects. Variability serves as a mechanism for coping with changing environments; however, this hypothesis does not explain why many of the variable phenomena of respiration manifest randomness. According to the constrained disorder principle (CDP), living organisms are defined by their inherent disorder bounded by variable boundaries. The present paper describes the mechanisms of breathing and cellular respiration, focusing on their inherent variability. It defines how the CDP accounts for the variability and randomness in breathing and respiration. It also provides a scheme for the potential role of respiration variability in the energy balance in biological systems. The paper describes the option of using CDP-based artificial intelligence platforms to augment the respiratory process's efficiency, correct malfunctions, and treat disorders associated with the respiratory system.
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Affiliation(s)
- Ofek Adar
- Faculty of Medicine, Hebrew University, Jerusalem P.O. Box 1200, Israel; (O.A.); (A.H.)
- Department of Medicine, Hadassah Medical Center, Jerusalem P.O. Box 1200, Israel
| | - Adi Hollander
- Faculty of Medicine, Hebrew University, Jerusalem P.O. Box 1200, Israel; (O.A.); (A.H.)
- Department of Medicine, Hadassah Medical Center, Jerusalem P.O. Box 1200, Israel
| | - Yaron Ilan
- Faculty of Medicine, Hebrew University, Jerusalem P.O. Box 1200, Israel; (O.A.); (A.H.)
- Department of Medicine, Hadassah Medical Center, Jerusalem P.O. Box 1200, Israel
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7
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Batterson PM, McGowan EM, Stierwalt HD, Ehrlicher SE, Newsom SA, Robinson MM. Two weeks of high-intensity interval training increases skeletal muscle mitochondrial respiration via complex-specific remodeling in sedentary humans. J Appl Physiol (1985) 2023; 134:339-355. [PMID: 36603044 DOI: 10.1152/japplphysiol.00467.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Aerobic training remodels the quantity and quality (function per unit) of skeletal muscle mitochondria to promote substrate oxidation, however, there remain key gaps in understanding the underlying mechanisms during initial training adaptations. We used short-term high-intensity interval training (HIIT) to determine changes to mitochondrial respiration and regulatory pathways that occur early in remodeling. Fifteen normal-weight sedentary adults started seven sessions of HIIT over 14 days and 14 participants completed the intervention. We collected vastus lateralis biopsies before and 48 h after HIIT to determine mitochondrial respiration, RNA sequencing, and Western blotting for proteins of mitochondrial respiration and degradation via autophagy. HIIT increased respiration per mitochondrial protein for lipid (+23% P = 0.020), complex I (+18%, P = 0.0015), complex I + II (+14%, P < 0.0001), and complex II (+24% P < 0.0001). Transcripts that increased with HIIT identified several gene sets of mitochondrial respiration, particularly for complex I, whereas transcripts that decreased identified pathways of DNA and chromatin remodeling. HIIT lowered protein abundance of autophagy markers for p62 (-19%, P = 0.012) and LC3 II/I (-20%, P = 0.004) in whole tissue lysates but not isolated mitochondria. Meal tolerance testing revealed HIIT increased the change in whole body respiratory exchange ratio and lowered cumulative plasma insulin concentrations. Gene transcripts and respiratory function indicate remodeling of mitochondria within 2 wk of HIIT. Overall changes are consistent with increased protein quality driving rapid improvements in substrate oxidation.NEW & NOTEWORTHY Aerobic training stimulates mitochondrial metabolism in skeletal muscle that is linked to improvements to whole body fuel metabolism. The mechanisms driving changes to the quantity and quality (function per unit) of mitochondria are less known. We used seven sessions of high-intensity interval training (HIIT) to determine functional changes and mechanisms of mitochondrial remodeling in skeletal muscle. HIIT increased mitochondrial respiration per mass for fatty acids, complex I, and complex II substrates. HIIT-induced remodeling pathways including gene transcripts for mitochondrial respiration (via RNA sequencing of muscle tissue) and proteins related to complex I respiration. We conclude that an early feature of aerobic training is increased mitochondrial protein quality via improved respiration and induction of mitochondrial transcriptional patterns.
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Affiliation(s)
- Philip M Batterson
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Erin M McGowan
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Harrison D Stierwalt
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Sarah E Ehrlicher
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Sean A Newsom
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Matthew M Robinson
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
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8
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Willoughby OS. Adrenergic restraint of blood flow and high-altitude acclimatization. J Physiol 2022; 600:5185-5186. [PMID: 36314729 DOI: 10.1113/jp283688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022] Open
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Cerda-Kohler H, Haichelis D, Reuquén P, Miarka B, Homer M, Zapata-Gómez D, Aedo-Muñoz E. Training at moderate altitude improves submaximal but not maximal performance-related parameters in elite rowers. Front Physiol 2022; 13:931325. [PMID: 36311238 PMCID: PMC9614325 DOI: 10.3389/fphys.2022.931325] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 09/30/2022] [Indexed: 11/13/2022] Open
Abstract
Maximal oxygen consumption (V̇O2max), physiological thresholds, and hemoglobin mass are strong predictors of endurance performance. High values of V̇O2max, maximal aerobic power (MAP), and power output at anaerobic thresholds are key variables in elite rowers. Endurance athletes often use altitude training as a strategy to improve performance. However, no clear evidence exists that training at natural altitude enhances sea-level performance in elite rowers. This study aimed to evaluate the effect of altitude training on rowing-performance parameters at sea level. The study was conducted on eleven rowers (Six females, five males) from the Chilean National Team during a 3-week moderate altitude training (∼2,900 m. a.s.l.) under the live high-train high (LHTH) model. It included a rowing ergometer maximal incremental test and blood analysis (pre and post-altitude). Gas exchange analysis was performed to measure V̇O2max, ventilatory thresholds (VTs) and rowing economy/efficiency (ECR/GE%). LHTL training improves performance-related variables at sea level (V̇Emax: 3.3% (95% CI, 1.2–5.5); hemoglobin concentration ([Hb]): 4.3% (95% CI, 1.7–6.9); hematocrit (%): 4.5% (95% CI, 0.9–8.2); RBC (red blood cells) count: 5.3% (95% CI, 2.3–8.2); power at VT2: 6.9% (95% CI, 1.7–12.1), V̇EVT2: 6.4% (95% CI, 0.4–12.4); power at VT1: 7.3% (95% CI, 1.3–13.3), V̇EVT1: 8.7% (95% CI, 1.6–15.8)) and economy/efficiency-related variables (ECRVT2: 5.3% (95% CI, −0.6 to −10.0); GE(%): 5.8% (95% CI, 0.8–10.7)). The LHTH training decreased breathing economy at MAP (−2.8% (95% CI, 0.1–5.6)), pVT2 (−9.3% (95% CI, −5.9 to −12.7)), and pVT1 (−9.3% (95% CI, −4.1 to −14.4)). Non-significant changes were found for V̇O2max and MAP. This study describes the effects of a 3-week moderate altitude (LHTH training) on performance and economy/efficiency-related variables in elite rowers, suggesting that it is an excellent option to induce positive adaptations related to endurance performance.
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Affiliation(s)
- Hugo Cerda-Kohler
- Escuela de Ciencias del Deporte y Actividad Física, Facultad de Salud, Universidad Santo Tomás, Santiago, Chile
- Departamento de Educación Física, eporte y Recreación, Facultad de Artes y Educación Física, Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile
- Laboratory of Psychophysiology and Performance in Sports and Combats, Postgraduate Program in Physical Education, School of Physical Education and Sport, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Unidad de Fisiología del Ejercicio, Centro de Innovación, Clínica MEDS, Santiago, Chile
| | - Danni Haichelis
- Unidad de Fisiología del Ejercicio, Centro de Innovación, Clínica MEDS, Santiago, Chile
- Unidad de Ciencias Aplicadas al Deporte, Instituto Nacional de Deportes, Santiago, Chile
| | - Patricia Reuquén
- Unidad de Ciencias Aplicadas al Deporte, Instituto Nacional de Deportes, Santiago, Chile
- Escuela de Ciencias de la Actividad Física, el Deporte y la Salud, Universidad de Santiago de Chile, Santiago, Chile
- Laboratorio de Ciencias de la Actividad Física, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Bianca Miarka
- Laboratory of Psychophysiology and Performance in Sports and Combats, Postgraduate Program in Physical Education, School of Physical Education and Sport, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mark Homer
- School of Human and Social Sciences, Buckinghamshire New University, Buckinghamshire, United Kingdom
| | - Daniel Zapata-Gómez
- Unidad de Ciencias Aplicadas al Deporte, Instituto Nacional de Deportes, Santiago, Chile
| | - Esteban Aedo-Muñoz
- Laboratory of Psychophysiology and Performance in Sports and Combats, Postgraduate Program in Physical Education, School of Physical Education and Sport, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Unidad de Ciencias Aplicadas al Deporte, Instituto Nacional de Deportes, Santiago, Chile
- Escuela de Ciencias de la Actividad Física, el Deporte y la Salud, Universidad de Santiago de Chile, Santiago, Chile
- *Correspondence: Esteban Aedo-Muñoz,
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10
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Hansen AB, Moralez G, Amin SB, Hofstätter F, Simpson LL, Gasho C, Tymko MM, Ainslie PN, Lawley JS, Hearon CM. Global REACH 2018: increased adrenergic restraint of blood flow preserves coupling of oxygen delivery and demand during exercise at high-altitude. J Physiol 2022; 600:3483-3495. [PMID: 35738560 PMCID: PMC9357095 DOI: 10.1113/jp282972] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 06/16/2022] [Indexed: 01/05/2023] Open
Abstract
Chronic exposure to hypoxia (high-altitude, HA; >4000 m) attenuates the vasodilatory response to exercise and is associated with a persistent increase in basal sympathetic nerve activity (SNA). The mechanism(s) responsible for the reduced vasodilatation and exercise hyperaemia at HA remains unknown. We hypothesized that heightened adrenergic signalling restrains skeletal muscle blood flow during handgrip exercise in lowlanders acclimatizing to HA. We tested nine adult males (n = 9) at sea-level (SL; 344 m) and following 21-28 days at HA (∼4300 m). Forearm blood flow (FBF; duplex ultrasonography), mean arterial pressure (MAP; brachial artery catheter), forearm vascular conductance (FVC; FBF/MAP), and arterial and venous blood sampling (O2 delivery ( DO2${D}_{{{\rm{O}}}_{\rm{2}}}$ ) and uptake ( V̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ )) were measured at rest and during graded rhythmic handgrip exercise (5%, 15% and 25% of maximum voluntary isometric contraction; MVC) before and after local α- and β-adrenergic blockade (intra-arterial phentolamine and propranolol). HA reduced ΔFBF (25% MVC: SL: 138.3 ± 47.6 vs. HA: 113.4 ± 37.1 ml min-1 ; P = 0.022) and Δ V̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ (25% MVC: SL: 20.3 ± 7.5 vs. HA: 14.3 ± 6.2 ml min-1 ; P = 0.014) during exercise. Local adrenoreceptor blockade at HA restored FBF during exercise (25% MVC: SLα-β blockade : 164.1 ± 71.7 vs. HAα-β blockade : 185.4 ± 66.6 ml min-1 ; P = 0.947) but resulted in an exaggerated relationship between DO2${D}_{{{\rm{O}}}_{\rm{2}}}$ and V̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ ( DO2${D}_{{{\rm{O}}}_{\rm{2}}}$ / V̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slope: SL: 1.32; HA: slope: 1.86; P = 0.037). These results indicate that tonic adrenergic signalling restrains exercise hyperaemia in lowlanders acclimatizing to HA. The increase in adrenergic restraint is necessary to match oxygen delivery to demand and prevent over perfusion of contracting muscle at HA. KEY POINTS: In exercising skeletal muscle, local vasodilatory signalling and sympathetic vasoconstriction integrate to match oxygen delivery to demand and maintain arterial blood pressure. Exposure to chronic hypoxia (altitude, >4000 m) causes a persistent increase in sympathetic nervous system activity that is associated with impaired functional capacity and diminished vasodilatation during exercise. In healthy male lowlanders exposed to chronic hypoxia (21-28 days; ∼4300 m), local adrenoreceptor blockade (combined α- and β-adrenergic blockade) restored skeletal muscle blood flow during handgrip exercise. However, removal of tonic adrenergic restraint at high altitude caused an excessive rise in blood flow and subsequently oxygen delivery for any given metabolic demand. This investigation is the first to identify greater adrenergic restraint of blood flow during acclimatization to high altitude and provides evidence of a functional role for this adaptive response in regulating oxygen delivery and demand.
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Affiliation(s)
| | - Gilbert Moralez
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, TX, USA
| | - Sachin B. Amin
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Florian Hofstätter
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Lydia L. Simpson
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Christopher Gasho
- Department of Medicine, Division of Pulmonary and Critical Care, University of Loma Linda, Loma Linda, California, USA
| | - Michael M. Tymko
- Physical Activity and Diabetes Laboratory, Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada.,Centre of Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia – Okanagan, Kelowna, British Columbia, Canada
| | - Philip N. Ainslie
- Centre of Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia – Okanagan, Kelowna, British Columbia, Canada
| | - Justin S. Lawley
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Christopher M. Hearon
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, TX, USA.,Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, TX, USA.,Correspondence: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, 7232 Greenville Avenue, Suite 435, Dallas, TX, 75231, USA.
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11
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Dawson NJ, Scott GR. Adaptive increases in respiratory capacity and O 2 affinity of subsarcolemmal mitochondria from skeletal muscle of high-altitude deer mice. FASEB J 2022; 36:e22391. [PMID: 35661419 DOI: 10.1096/fj.202200219r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/05/2022] [Accepted: 05/23/2022] [Indexed: 11/11/2022]
Abstract
Aerobic energy demands have led to the evolution of complex mitochondrial reticula in highly oxidative muscles, but the extent to which metabolic challenges can be met with adaptive changes in physiology of specific mitochondrial fractions remains unresolved. We examined mitochondrial mechanisms supporting adaptive increases in aerobic performance in deer mice (Peromyscus maniculatus) adapted to the hypoxic environment at high altitude. High-altitude and low-altitude mice were born and raised in captivity, and exposed as adults to normoxia or hypobaric hypoxia (12 kPa O2 for 6-8 weeks). Subsarcolemmal and intermyofibrillar mitochondria were isolated from the gastrocnemius, and a comprehensive substrate titration protocol was used to examine mitochondrial physiology and O2 kinetics by high-resolution respirometry and fluorometry. High-altitude mice had greater yield, respiratory capacity for oxidative phosphorylation, and O2 affinity (lower P50 ) of subsarcolemmal mitochondria compared to low-altitude mice across environments, but there were no species difference in these traits in intermyofibrillar mitochondria. High-altitude mice also had greater capacities of complex II relative to complexes I + II and higher succinate dehydrogenase activities in both mitochondrial fractions. Exposure to chronic hypoxia reduced reactive oxygen species (ROS) emission in high-altitude mice but not in low-altitude mice. Our findings suggest that functional changes in subsarcolemmal mitochondria contribute to improving aerobic performance in hypoxia in high-altitude deer mice. Therefore, physiological variation in specific mitochondrial fractions can help overcome the metabolic challenges of life at high altitude.
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Affiliation(s)
- Neal J Dawson
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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12
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Analysis of Reasonable Respiratory Efficiency in Tennis Competition and Training Environment Based on Cloud Computing. JOURNAL OF HEALTHCARE ENGINEERING 2022; 2022:4289667. [PMID: 35480156 PMCID: PMC9038377 DOI: 10.1155/2022/4289667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 01/19/2022] [Accepted: 03/11/2022] [Indexed: 11/23/2022]
Abstract
Competitive tennis is developing in the direction of quantification. How to use and give full play to all positive factors, in order to attack actively and give full play to the limits of body and psychology, breathing, as the basic metabolic function of human body, also plays a vital role in tennis. This paper studies that it plays an important role in the rationality and explosiveness of sports and the psychological and physiological regulation in competition. The characteristics of tennis events determine the importance of scientific and rational breathing. Reasonable breathing during exercise is conducive to maintaining the basic stability of the internal environment, improving the training effect, and giving full play to the functional ability of the human body, so as to create excellent sports results. First, reduce respiratory resistance. Second, there are two methods to improve alveolar ventilation efficiency and pulmonary ventilation: increasing respiratory rate and increasing respiratory depth. When the inhalation volume is constant, the alveolar gas freshness rate depends on the functional residual volume in the alveolar cavity at the end of expiratory or before inhalation. The less functional the residual air, the more fresh air inhaled, and the higher the oxygen partial pressure in alveolar gas. An effective way to reduce the functional residual volume in the alveolar cavity is to exhale as deeply as possible, so as to ensure that more oxygen enters the body. Reasonable breathing methods can not only accelerate the excitation of the body, increase movement strength, reduce fatigue, and promote recovery but also play a vital role in the rational allocation of physical fitness and the improvement of sports performance. The purpose of this study is to provide a theoretical basis for scientific tennis training by analyzing the characteristics of tennis events, the form of breathing in tennis and the efficiency of reasonable breathing in tennis.
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13
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Ruggiero L, Harrison SWD, Rice CL, McNeil CJ. Neuromuscular fatigability at high altitude: Lowlanders with acute and chronic exposure, and native highlanders. Acta Physiol (Oxf) 2022; 234:e13788. [PMID: 35007386 PMCID: PMC9286620 DOI: 10.1111/apha.13788] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 01/18/2023]
Abstract
Ascent to high altitude is accompanied by a reduction in partial pressure of inspired oxygen, which leads to interconnected adjustments within the neuromuscular system. This review describes the unique challenge that such an environment poses to neuromuscular fatigability (peripheral, central and supraspinal) for individuals who normally reside near to sea level (SL) (<1000 m; ie, lowlanders) and for native highlanders, who represent the manifestation of high altitude-related heritable adaptations across millennia. Firstly, the effect of acute exposure to high altitude-related hypoxia on neuromuscular fatigability will be examined. Under these conditions, both supraspinal and peripheral fatigability are increased compared with SL. The specific mechanisms contributing to impaired performance are dependent on the exercise paradigm and amount of muscle mass involved. Next, the effect of chronic exposure to high altitude (ie, acclimatization of ~7-28 days) will be considered. With acclimatization, supraspinal fatigability is restored to SL values, regardless of the amount of muscle mass involved, whereas peripheral fatigability remains greater than SL except when exercise involves a small amount of muscle mass (eg, knee extensors). Indeed, when whole-body exercise is involved, peripheral fatigability is not different to acute high-altitude exposure, due to competing positive (haematological and muscle metabolic) and negative (respiratory-mediated) effects of acclimatization on neuromuscular performance. In the final section, we consider evolutionary adaptations of native highlanders (primarily Himalayans of Tibet and Nepal) that may account for their superior performance at altitude and lesser degree of neuromuscular fatigability compared with acclimatized lowlanders, for both single-joint and whole-body exercise.
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Affiliation(s)
- Luca Ruggiero
- Laboratory of Physiomechanics of Locomotion Department of Pathophysiology and Transplantation University of Milan Milan Italy
| | - Scott W. D. Harrison
- School of Kinesiology Faculty of Health Sciences The University of Western Ontario London Ontario Canada
| | - Charles L. Rice
- School of Kinesiology Faculty of Health Sciences The University of Western Ontario London Ontario Canada
- Department of Anatomy and Cell Biology Schulich School of Medicine and Dentistry The University of Western Ontario London Ontario Canada
| | - Chris J. McNeil
- Centre for Heart, Lung & Vascular Health School of Health and Exercise Sciences University of British Columbia Kelowna British Columbia Canada
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14
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Rudloff S, Bileck A, Janker L, Wanner N, Liaukouskaya N, Lundby C, Huber TB, Gerner C, Huynh-Do U. Dichotomous responses to chronic fetal hypoxia lead to a predetermined aging phenotype. Mol Cell Proteomics 2021; 21:100190. [PMID: 34958949 PMCID: PMC8808178 DOI: 10.1016/j.mcpro.2021.100190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/07/2021] [Accepted: 12/21/2021] [Indexed: 12/29/2022] Open
Abstract
Hypoxia-induced intrauterine growth restriction increases the risk for cardiovascular, renal and other chronic diseases in adults, representing thus a major public health problem. Still, not much is known about the fetal mechanisms that predispose these individuals to disease. Using a previously validated mouse model of fetal hypoxia and bottom-up proteomics we characterize the response of the fetal kidney to chronic hypoxic stress. Fetal kidneys exhibit a dichotomous response to chronic hypoxia, comprising on the one hand cellular adaptations that promote survival (glycolysis, autophagy, and reduced DNA and protein synthesis), but on the other processes that induce a senescence-like phenotype (infiltration of inflammatory cells, DNA damage, and reduced proliferation). Importantly, chronic hypoxia also reduces the expression of the anti-aging proteins klotho and Sirt6, a mechanism that is evolutionary conserved between mice and humans. Taken together, we uncover that predetermined aging during fetal development is a key event in chronic hypoxia, establishing a solid foundation for Barker's hypothesis of fetal programming of adult diseases. This phenotype is associated with a characteristic biomarker profile in tissue and serum samples, exploitable for detecting and targeting accelerated aging in chronic hypoxic human diseases.
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Affiliation(s)
- Stefan Rudloff
- Division of Nephrology and Hypertension, University of Bern and University Hospital Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland
| | - Andrea Bileck
- Department of Analytical Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Strasse 38, A-1090 Vienna, Austria
| | - Lukas Janker
- Department of Analytical Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Strasse 38, A-1090 Vienna, Austria
| | - Nicola Wanner
- University Medical Center Hamburg-Eppendorf, III. Medizinische Klinik und Poliklinik, Martinistrasse 52, D-20246 Hamburg, Germany
| | - Nastassia Liaukouskaya
- University Medical Center Hamburg-Eppendorf, III. Medizinische Klinik und Poliklinik, Martinistrasse 52, D-20246 Hamburg, Germany
| | - Carsten Lundby
- Centre for Physical Activity Research (CFAS), Rigshospitalet Section 7641, Ole Maaloesvej 24, DK-2100 Copenhagen, Denmark; Faculty of Social and Health Sciences, Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, NO-2624 Lillehammer, Norway
| | - Tobias B Huber
- University Medical Center Hamburg-Eppendorf, III. Medizinische Klinik und Poliklinik, Martinistrasse 52, D-20246 Hamburg, Germany
| | - Christopher Gerner
- Department of Analytical Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Strasse 38, A-1090 Vienna, Austria.
| | - Uyen Huynh-Do
- Division of Nephrology and Hypertension, University of Bern and University Hospital Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland.
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15
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Rathor R, Suryakumar G, Singh SN. Diet and redox state in maintaining skeletal muscle health and performance at high altitude. Free Radic Biol Med 2021; 174:305-320. [PMID: 34352371 DOI: 10.1016/j.freeradbiomed.2021.07.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/14/2021] [Accepted: 07/19/2021] [Indexed: 01/07/2023]
Abstract
High altitude exposure leads to compromised physical performance with considerable weight loss. The major stressor at high altitude is hypobaric hypoxia which leads to disturbance in redox homeostasis. Oxidative stress is a well-known trigger for many high altitude illnesses and regulates several key signaling pathways under stressful conditions. Altered redox homeostasis is considered the prime culprit of high altitude linked skeletal muscle atrophy. Hypobaric hypoxia disturbs redox homeostasis through increased RONS production and compromised antioxidant system. Increased RONS disturbs the cellular homeostasis via multiple ways such as inflammation generation, altered protein anabolic pathways, redox remodeling of RyR1 that contributed to dysregulated calcium homeostasis, enhanced protein degradation pathways via activation calcium-regulated protein, calpain, and apoptosis. Ultimately, all the cellular signaling pathways aggregately result in skeletal muscle atrophy. Dietary supplementation of phytochemicals could become a safe and effective intervention to ameliorate skeletal muscle atrophy and enhance the physical performance of the personnel who are staying at high altitude regions. The present evidence-based review explores few dietary supplementations which regulate several signaling mechanisms and ameliorate hypobaric hypoxia induced muscle atrophy and enhances physical performance. However, a clinical research trial is required to establish proof-of-concept.
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Affiliation(s)
- Richa Rathor
- Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, New Delhi, 110054, India.
| | - Geetha Suryakumar
- Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, New Delhi, 110054, India
| | - Som Nath Singh
- Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, New Delhi, 110054, India
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16
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Galli GLJ, Ruhr IM, Crossley J, Crossley DA. The Long-Term Effects of Developmental Hypoxia on Cardiac Mitochondrial Function in Snapping Turtles. Front Physiol 2021; 12:689684. [PMID: 34262478 PMCID: PMC8273549 DOI: 10.3389/fphys.2021.689684] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/03/2021] [Indexed: 01/05/2023] Open
Abstract
It is well established that adult vertebrates acclimatizing to hypoxic environments undergo mitochondrial remodeling to enhance oxygen delivery, maintain ATP, and limit oxidative stress. However, many vertebrates also encounter oxygen deprivation during embryonic development. The effects of developmental hypoxia on mitochondrial function are likely to be more profound, because environmental stress during early life can permanently alter cellular physiology and morphology. To this end, we investigated the long-term effects of developmental hypoxia on mitochondrial function in a species that regularly encounters hypoxia during development-the common snapping turtle (Chelydra serpentina). Turtle eggs were incubated in 21% or 10% oxygen from 20% of embryonic development until hatching, and both cohorts were subsequently reared in 21% oxygen for 8 months. Ventricular mitochondria were isolated, and mitochondrial respiration and reactive oxygen species (ROS) production were measured with a microrespirometer. Compared to normoxic controls, juvenile turtles from hypoxic incubations had lower Leak respiration, higher P:O ratios, and reduced rates of ROS production. Interestingly, these same attributes occur in adult vertebrates that acclimatize to hypoxia. We speculate that these adjustments might improve mitochondrial hypoxia tolerance, which would be beneficial for turtles during breath-hold diving and overwintering in anoxic environments.
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Affiliation(s)
- Gina L. J. Galli
- Faculty of Biology, Medicine, and Health, School of Medical Sciences, The University of Manchester, Manchester, United Kingdom
| | - Ilan M. Ruhr
- Faculty of Biology, Medicine, and Health, School of Medical Sciences, The University of Manchester, Manchester, United Kingdom
| | - Janna Crossley
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, TX, United States
| | - Dane A. Crossley
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, TX, United States
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17
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Malgoyre A, Prola A, Meunier A, Chapot R, Serrurier B, Koulmann N, Bigard X, Sanchez H. Endurance Is Improved in Female Rats After Living High-Training High Despite Alterations in Skeletal Muscle. Front Sports Act Living 2021; 3:663857. [PMID: 34124658 PMCID: PMC8193088 DOI: 10.3389/fspor.2021.663857] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/12/2021] [Indexed: 11/29/2022] Open
Abstract
Altitude camps are used during the preparation of endurance athletes to improve performance based on the stimulation of erythropoiesis by living at high altitude. In addition to such whole-body adaptations, studies have suggested that high-altitude training increases mitochondrial mass, but this has been challenged by later studies. Here, we hypothesized that living and training at high altitude (LHTH) improves mitochondrial efficiency and/or substrate utilization. Female rats were exposed and trained in hypoxia (simulated 3,200 m) for 5 weeks (LHTH) and compared to sedentary rats living in hypoxia (LH) or normoxia (LL) or those that trained in normoxia (LLTL). Maximal aerobic velocity (MAV) improved with training, independently of hypoxia, whereas the time to exhaustion, performed at 65% of MAV, increased both with training (P = 0.009) and hypoxia (P = 0.015), with an additive effect of the two conditions. The distance run was 7.98 ± 0.57 km in LHTH vs. 6.94 ± 0.51 in LLTL (+15%, ns). The hematocrit increased >20% with hypoxia (P < 0.001). The increases in mitochondrial mass and maximal oxidative capacity with endurance training were blunted by combination with hypoxia (−30% for citrate synthase, P < 0.01, and −23% for Vmax glut−succ, P < 0.001 between LHTH and LLTL). A similar reduction between the LHTH and LLTL groups was found for maximal respiration with pyruvate (−29%, P < 0.001), for acceptor-control ratio (−36%, hypoxia effect, P < 0.001), and for creatine kinase efficiency (−48%, P < 0.01). 3-hydroxyl acyl coenzyme A dehydrogenase was not altered by hypoxia, whereas maximal respiration with Palmitoyl-CoA specifically decreased. Overall, our results show that mitochondrial adaptations are not involved in the improvement of submaximal aerobic performance after LHTH, suggesting that the benefits of altitude camps in females relies essentially on other factors, such as the transitory elevation of hematocrit, and should be planned a few weeks before competition and not several months.
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Affiliation(s)
- Alexandra Malgoyre
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.,Laboratoire de Biologie de l'Exercice pour la Performance et la Santé, Université Evry, Université Paris Saclay, Evry, France
| | - Alexandre Prola
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Adelie Meunier
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Rachel Chapot
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Bernard Serrurier
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Nathalie Koulmann
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.,Laboratoire de Biologie de l'Exercice pour la Performance et la Santé, Université Evry, Université Paris Saclay, Evry, France.,Ecole du Val de Grâce, Paris, France
| | - Xavier Bigard
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.,Ecole du Val de Grâce, Paris, France
| | - Hervé Sanchez
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
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18
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Ferri A, Yan X, Kuang J, Granata C, Oliveira RSF, Hedges CP, Lima-Silva AE, Billaut F, Bishop DJ. Fifteen days of moderate normobaric hypoxia does not affect mitochondrial function, and related genes and proteins, in healthy men. Eur J Appl Physiol 2021; 121:2323-2336. [PMID: 33988746 DOI: 10.1007/s00421-021-04706-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/28/2021] [Indexed: 11/28/2022]
Abstract
PURPOSE To investigate within the one study potential molecular and cellular changes associated with mitochondrial biogenesis following 15 days of exposure to moderate hypoxia. METHODS Eight males underwent a muscle biopsy before and after 15 days of hypoxia exposure (FiO2 = 0.140-0.154; ~ 2500-3200 m) in a hypoxic hotel. Mitochondrial respiration, citrate synthase (CS) activity, and the content of genes and proteins associated with mitochondrial biogenesis were investigated. RESULTS Our main findings were the absence of significant changes in the mean values of CS activity, mitochondrial respiration in permeabilised fibers, or the content of genes and proteins associated with mitochondrial biogenesis, after 15 days of moderate normobaric hypoxia. CONCLUSION Our data provide evidence that 15 days of moderate normobaric hypoxia have negligible influence on skeletal muscle mitochondrial content and function, or genes and proteins content associated with mitochondrial biogenesis, in young recreationally active males. However, the increase in mitochondrial protease LON content after hypoxia exposure suggests the possibility of adaptations to optimise respiratory chain function under conditions of reduced O2 availability.
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Affiliation(s)
- Alessandra Ferri
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Xu Yan
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Jujiao Kuang
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Cesare Granata
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.,Department of Diabetes, Central Clinical School, Monash University, Alfred Medical Research and Education Precinct, Melbourne, VIC, Australia
| | | | | | - Adriano E Lima-Silva
- Human Performance Research Group, Federal University of Technology-Parana (UTFPR), Curitiba, Brazil
| | - Francois Billaut
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.,Département de Kinésiologie, Université Laval, Québec, Canada
| | - David J Bishop
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.
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19
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Jacobs RA, Lundby C. Contextualizing the biological relevance of standardized high-resolution respirometry to assess mitochondrial function in permeabilized human skeletal muscle. Acta Physiol (Oxf) 2021; 231:e13625. [PMID: 33570804 PMCID: PMC8047922 DOI: 10.1111/apha.13625] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/16/2022]
Abstract
Aim This study sought to provide a statistically robust reference for measures of mitochondrial function from standardized high‐resolution respirometry with permeabilized human skeletal muscle (ex vivo), compare analogous values obtained via indirect calorimetry, arterial‐venous O2 differences and 31P magnetic resonance spectroscopy (in vivo) and attempt to resolve differences across complementary methodologies as necessary. Methods Data derived from 831 study participants across research published throughout March 2009 to November 2019 were amassed to examine the biological relevance of ex vivo assessments under standard conditions, ie physiological temperatures of 37°C and respiratory chamber oxygen concentrations of ~250 to 500 μmol/L. Results Standard ex vivo‐derived measures are lower (Z ≥ 3.01, P ≤ .0258) en masse than corresponding in vivo‐derived values. Correcting respiratory values to account for mitochondrial temperatures 10°C higher than skeletal muscle temperatures at maximal exercise (~50°C): (i) transforms data to resemble (Z ≤ 0.8, P > .9999) analogous yet context‐specific in vivo measures, eg data collected during maximal 1‐leg knee extension exercise; and (ii) supports the position that maximal skeletal muscle respiratory rates exceed (Z ≥ 13.2, P < .0001) those achieved during maximal whole‐body exercise, e.g. maximal cycling efforts. Conclusion This study outlines and demonstrates necessary considerations when actualizing the biological relevance of human skeletal muscle respiratory control, metabolic flexibility and bioenergetics from standard ex vivo‐derived assessments using permeabilized human muscle. These findings detail how cross‐procedural comparisons of human skeletal muscle mitochondrial function may be collectively scrutinized in their relationship to human health and lifespan.
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Affiliation(s)
- Robert A. Jacobs
- Department of Human Physiology & Nutrition University of Colorado Colorado Springs (UCCS) Colorado Springs CO USA
| | - Carsten Lundby
- Innland University of Applied Sciences Lillehammer Norway
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20
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Cheng H, Munro D, Huynh K, Pamenter ME. Naked mole-rat skeletal muscle mitochondria exhibit minimal functional plasticity in acute or chronic hypoxia. Comp Biochem Physiol B Biochem Mol Biol 2021; 255:110596. [PMID: 33757832 DOI: 10.1016/j.cbpb.2021.110596] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 01/10/2023]
Abstract
Oxidative phosphorylation is compromised in hypoxia, but many organisms live and exercise in low oxygen environments. Hypoxia-driven adaptations at the mitochondrial level are common and may enhance energetic efficiency or minimize deleterious reactive oxygen species (ROS) generation. Mitochondria from various hypoxia-tolerant animals exhibit robust functional changes following in vivo hypoxia and we hypothesized that similar plasticity would occur in naked mole-rat skeletal muscle. To test this, we exposed adult subordinate naked mole-rats to normoxia (21% O2) or acute (4 h, 7% O2) or chronic hypoxia (4-6 weeks, 11% O2) and then isolated skeletal muscle mitochondria. Using high-resolution respirometry and a fluorescent indicator of ROS production, we then probed for changes in: i) lipid- (palmitoylcarnitine-malate), ii) carbohydrate- (pyruvate-malate), and iii) succinate-fueled metabolism, and also iv) complex IV electron transfer capacity, and v) H2O2 production. Compared to normoxic values, a) lipid-fueled uncoupled respiration was reduced ~15% during acute and chronic hypoxia, b) complex I-II capacity and the rate of ROS efflux were both unaffected, and c) complex II and IV uncoupled respiration were supressed ~16% following acute hypoxia. Notably, complex II-linked H2O2 efflux was 33% lower after acute hypoxia, which may reduce deleterious ROS bursts during reoxygenation. These mild changes in lipid- and carbohydrate-fueled respiratory capacity may reflect the need for this animal to exercise regularly in highly variable and intermittently hypoxic environments in which more robust plasticity may be energetically expensive.
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Affiliation(s)
- Hang Cheng
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Daniel Munro
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Kenny Huynh
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Matthew E Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada; University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
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21
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Abstract
The syndrome of critical illness is a complex physiological stressor that can be triggered by diverse pathologies. It is widely believed that organ dysfunction and death result from bioenergetic failure caused by inadequate cellular oxygen supply. Teleologically, life has evolved to survive in the face of stressors by undergoing a suite of adaptive changes. Adaptation not only comprises alterations in systemic physiology but also involves molecular reprogramming within cells. The concept of cellular adaptation in critically ill patients is a matter of contention in part because medical interventions mask underlying physiology, creating the artificial construct of "chronic critical illness," without which death would be imminent. Thus far, the intensive care armamentarium has not targeted cellular metabolism to preserve a temporary equilibrium but instead attempts to normalize global oxygen and substrate delivery. Here, we review adaptations to hypoxia that have been demonstrated in cellular models and in human conditions associated with hypoxia, including the hypobaric hypoxia of high altitude, the intrauterine low-oxygen environment, and adult myocardial hibernation. Common features include upregulation of glycolytic ATP production, enhancement of respiratory efficiency, downregulation of mitochondrial density, and suppression of energy-consuming processes. We argue that these innate cellular adaptations to hypoxia represent potential avenues for intervention that have thus far remained untapped by intensive care medicine.
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Affiliation(s)
- Helen T McKenna
- Division of Surgery and Interventional Science, University College London, London, United Kingdom.,Royal Free Intensive Care Unit, Royal Free Hospital, London, United Kingdom
| | - Andrew J Murray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Daniel S Martin
- Royal Free Intensive Care Unit, Royal Free Hospital, London, United Kingdom.,Peninsula Medical School, University of Plymouth, Plymouth, United Kingdom
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22
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Dawson NJ, Alza L, Nandal G, Scott GR, McCracken KG. Convergent changes in muscle metabolism depend on duration of high-altitude ancestry across Andean waterfowl. eLife 2020; 9:e56259. [PMID: 32729830 PMCID: PMC7494360 DOI: 10.7554/elife.56259] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/23/2020] [Indexed: 01/07/2023] Open
Abstract
High-altitude environments require that animals meet the metabolic O2 demands for locomotion and thermogenesis in O2-thin air, but the degree to which convergent metabolic changes have arisen across independent high-altitude lineages or the speed at which such changes arise is unclear. We examined seven high-altitude waterfowl that have inhabited the Andes (3812-4806 m elevation) over varying evolutionary time scales, to elucidate changes in biochemical pathways of energy metabolism in flight muscle relative to low-altitude sister taxa. Convergent changes across high-altitude taxa included increased hydroxyacyl-coA dehydrogenase and succinate dehydrogenase activities, decreased lactate dehydrogenase, pyruvate kinase, creatine kinase, and cytochrome c oxidase activities, and increased myoglobin content. ATP synthase activity increased in only the longest established high-altitude taxa, whereas hexokinase activity increased in only newly established taxa. Therefore, changes in pathways of lipid oxidation, glycolysis, and mitochondrial oxidative phosphorylation are common strategies to cope with high-altitude hypoxia, but some changes require longer evolutionary time to arise.
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Affiliation(s)
- Neal J Dawson
- Department of Biology, McMaster UniversityHamiltonCanada
- Department of Biology University of MiamiCoral GablesUnited States
| | - Luis Alza
- Department of Biology University of MiamiCoral GablesUnited States
- University of Alaska Museum and Institute of Arctic Biology, University of Alaska FairbanksFairbanksUnited States
- Centro de Ornitología y Biodiversidad - CORBIDILimaPeru
| | | | - Graham R Scott
- Department of Biology, McMaster UniversityHamiltonCanada
| | - Kevin G McCracken
- Department of Biology University of MiamiCoral GablesUnited States
- University of Alaska Museum and Institute of Arctic Biology, University of Alaska FairbanksFairbanksUnited States
- Centro de Ornitología y Biodiversidad - CORBIDILimaPeru
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of MiamiMiamiUnited States
- Human Genetics and Genomics, Hussman Institute for Human Genomics, University of Miami Miller School of MedicineMiamiUnited States
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23
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Batterson PM, Norton MR, Hetz SE, Rohilla S, Lindsay KG, Subudhi AW, Jacobs RA. Improving biologic predictors of cycling endurance performance with near-infrared spectroscopy derived measures of skeletal muscle respiration: E pluribus unum. Physiol Rep 2020; 8:e14342. [PMID: 31960629 PMCID: PMC6971325 DOI: 10.14814/phy2.14342] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The study aim was to compare the predictive validity of the often referenced traditional model of human endurance performance (i.e. oxygen consumption, VO2 , or power at maximal effort, fatigue threshold values, and indices of exercise efficiency) versus measures of skeletal muscle oxidative potential in relation to endurance cycling performance. We hypothesized that skeletal muscle oxidative potential would more completely explain endurance performance than the traditional model, which has never been collectively verified with cycling. Accordingly, we obtained nine measures of VO2 or power at maximal efforts, 20 measures reflective of various fatigue threshold values, 14 indices of cycling efficiency, and near-infrared spectroscopy-derived measures reflecting in vivo skeletal muscle oxidative potential. Forward regression modeling identified variable combinations that best explained 25-km time trial time-to-completion (TTC) across a group of trained male participants (n = 24). The time constant for skeletal muscle oxygen consumption recovery, a validated measure of maximal skeletal muscle respiration, explained 92.7% of TTC variance by itself (Adj R2 = .927, F = 294.2, SEE = 71.2, p < .001). Alternatively, the best complete traditional model of performance, including VO2max (L·min-1 ), %VO2max determined by the ventilatory equivalents method, and cycling economy at 50 W, only explained 76.2% of TTC variance (Adj R2 = .762, F = 25.6, SEE = 128.7, p < .001). These results confirm our hypothesis by demonstrating that maximal rates of skeletal muscle respiration more completely explain cycling endurance performance than even the best combination of traditional variables long postulated to predict human endurance performance.
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Affiliation(s)
- Philip M. Batterson
- Department of BiologyUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Michael R. Norton
- Department of BiologyUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Sarah E. Hetz
- Department of BiologyUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Sachi Rohilla
- Department of BiologyUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Keston G. Lindsay
- Department of Human Physiology and NutritionUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
- Department of Health SciencesUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Andrew W. Subudhi
- Department of BiologyUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
- Department of Human Physiology and NutritionUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Robert A. Jacobs
- Department of BiologyUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
- Department of Human Physiology and NutritionUniversity of Colorado Colorado SpringsColorado SpringsCOUSA
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24
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Grocott MPW, Levett DZH, Ward SA. Exercise physiology: exercise performance at altitude. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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25
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Ruggiero L, Hoiland RL, Hansen AB, Ainslie PN, McNeil CJ. High-Altitude Acclimatization Improves Recovery from Muscle Fatigue. Med Sci Sports Exerc 2019; 52:161-169. [PMID: 31343519 DOI: 10.1249/mss.0000000000002100] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE We investigated the effect of high-altitude acclimatization on peripheral fatigue compared with sea level and acute hypoxia. METHODS At sea level (350 m), acute hypoxia (environmental chamber), and chronic hypoxia (5050 m, 5-9 d) (partial pressure of inspired oxygen = 140, 74 and 76 mm Hg, respectively), 12 participants (11 in chronic hypoxia) had the quadriceps of their dominant leg fatigued by three bouts of 75 intermittent electrically evoked contractions (12 pulses at 15 Hz, 1.6 s between train onsets, and 15 s between bouts). The initial peak force was ~30% of maximal voluntary force. Recovery was assessed by single trains at 1, 2, and 3 min postprotocol. Tissue oxygenation of rectus femoris was recorded by near-infrared spectroscopy. RESULTS At the end of the fatigue protocol, the impairments of peak force and peak rates of force development and relaxation were greater (all P < 0.05) in acute hypoxia (~51%, 53%, and 64%, respectively) than sea level (~43%, 43%, and 52%) and chronic hypoxia (~38%, 35%, and 48%). Peak force and rate of force development recovered faster (P < 0.05) in chronic hypoxia (pooled data for 1-3 min: ~84% and 74% baseline, respectively) compared with sea level (~73% and 63% baseline) and acute hypoxia (~70% and 55% baseline). Tissue oxygenation did not differ among conditions for fatigue or recovery (P > 0.05). CONCLUSIONS Muscle adaptations occurring with chronic hypoxia, independent of other adaptations, positively influence muscle contractility during and after repeated contractions at high altitude.
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Affiliation(s)
- Luca Ruggiero
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, CANADA
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26
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Fiorenza M, Lemminger AK, Marker M, Eibye K, Iaia FM, Bangsbo J, Hostrup M. High-intensity exercise training enhances mitochondrial oxidative phosphorylation efficiency in a temperature-dependent manner in human skeletal muscle: implications for exercise performance. FASEB J 2019; 33:8976-8989. [PMID: 31136218 DOI: 10.1096/fj.201900106rrr] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The purpose of the present study was to investigate whether exercise training-induced adaptations in human skeletal muscle mitochondrial bioenergetics are magnified under thermal conditions resembling sustained intense contractile activity and whether training-induced changes in mitochondrial oxidative phosphorylation (OXPHOS) efficiency influence exercise efficiency. Twenty healthy men performed 6 wk of high-intensity exercise training [i.e., speed endurance training (SET; n = 10)], or maintained their usual lifestyle (n = 10). Before and after the intervention, mitochondrial respiratory function was determined ex vivo in permeabilized muscle fibers under experimentally-induced normothermia (35°C) and hyperthermia (40°C) mimicking in vivo muscle temperature at rest and during intense exercise, respectively. In addition, activity and content of muscle mitochondrial enzymes and proteins were quantified. Exercising muscle efficiency was determined in vivo by measurements of leg hemodynamics and blood parameters during one-legged knee-extensor exercise. SET enhanced maximal OXPHOS capacity and OXPHOS efficiency at 40°C, but not at 35°C, and attenuated hyperthermia-induced decline in OXPHOS efficiency. Furthermore, SET increased expression of markers of mitochondrial content and up-regulated content of MFN2, DRP1, and ANT1. Also, SET improved exercise efficiency and capacity. These findings indicate that muscle mitochondrial bioenergetics adapts to high-intensity exercise training in a temperature-dependent manner and that enhancements in mitochondrial OXPHOS efficiency may contribute to improving exercise performance.-Fiorenza, M., Lemminger, A. K., Marker, M., Eibye, K., Iaia, F. M., Bangsbo, J., Hostrup, M. High-intensity exercise training enhances mitochondrial oxidative phosphorylation efficiency in a temperature-dependent manner in human skeletal muscle: implications for exercise performance.
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Affiliation(s)
- Matteo Fiorenza
- Section of Integrative Physiology, Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark.,Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, Italy
| | - Anders K Lemminger
- Section of Integrative Physiology, Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Mathias Marker
- Section of Integrative Physiology, Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Kasper Eibye
- Section of Integrative Physiology, Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - F Marcello Iaia
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Jens Bangsbo
- Section of Integrative Physiology, Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
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27
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Bishop DJ, Botella J, Genders AJ, Lee MJC, Saner NJ, Kuang J, Yan X, Granata C. High-Intensity Exercise and Mitochondrial Biogenesis: Current Controversies and Future Research Directions. Physiology (Bethesda) 2019; 34:56-70. [PMID: 30540234 DOI: 10.1152/physiol.00038.2018] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It is well established that different types of exercise can provide a powerful stimulus for mitochondrial biogenesis. However, there are conflicting findings in the literature, and a consensus has not been reached regarding the efficacy of high-intensity exercise to promote mitochondrial biogenesis in humans. The purpose of this review is to examine current controversies in the field and to highlight some important methodological issues that need to be addressed to resolve existing conflicts.
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Affiliation(s)
- David J Bishop
- Institute for Health and Sport, Victoria University , Melbourne , Australia.,School of Medical & Health Sciences, Edith Cowan University , Joondalup , Australia
| | - Javier Botella
- Institute for Health and Sport, Victoria University , Melbourne , Australia
| | - Amanda J Genders
- Institute for Health and Sport, Victoria University , Melbourne , Australia
| | - Matthew J-C Lee
- Institute for Health and Sport, Victoria University , Melbourne , Australia
| | - Nicholas J Saner
- Institute for Health and Sport, Victoria University , Melbourne , Australia
| | - Jujiao Kuang
- Institute for Health and Sport, Victoria University , Melbourne , Australia
| | - Xu Yan
- Institute for Health and Sport, Victoria University , Melbourne , Australia
| | - Cesare Granata
- Department of Diabetes, Central Clinical School, Monash University , Melbourne , Australia
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28
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O'Brien KA, Pollock RD, Stroud M, Lambert RJ, Kumar A, Atkinson RA, Green DA, Anton-Solanas A, Edwards LM, Harridge SDR. Human physiological and metabolic responses to an attempted winter crossing of Antarctica: the effects of prolonged hypobaric hypoxia. Physiol Rep 2019. [PMID: 29521037 PMCID: PMC5843758 DOI: 10.14814/phy2.13613] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
An insufficient supply of oxygen to the tissues (hypoxia), as is experienced upon high‐altitude exposure, elicits physiological acclimatization mechanisms alongside metabolic remodeling. Details of the integrative adaptive processes in response to chronic hypobaric hypoxic exposure remain to be sufficiently investigated. In this small applied field study, subjects (n = 5, male, age 28–54 years) undertook a 40 week Antarctica expedition in the winter months, which included 24 weeks residing above 2500 m. Measurements taken pre‐ and postexpedition revealed alterations to glucose and fatty acid resonances within the serum metabolic profile, a 7.8 (±3.6)% increase in respiratory exchange ratio measured during incremental exercise (area under curve, P > 0.01, mean ± SD) and a 2.1(±0.8) % decrease in fat tissue (P < 0.05) postexpedition. This was accompanied by an 11.6 (±1.9) % increase (P > 0.001) in VO2 max corrected to % lean mass postexpedition. In addition, spine bone mineral density and lung function measures were identified as novel parameters of interest. This study provides, an in‐depth characterization of the responses to chronic hypobaric hypoxic exposure in one of the most hostile environments on Earth.
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Affiliation(s)
- Katie A O'Brien
- Centre of Human and Aerospace Physiological Sciences, King's College London, London, United Kingdom.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Ross D Pollock
- Centre of Human and Aerospace Physiological Sciences, King's College London, London, United Kingdom
| | - Mike Stroud
- Biomedical Research Centre in Nutrition, Southampton University Hospitals Trust, Southampton, United Kingdom
| | - Rob J Lambert
- Department of Trauma and Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom
| | - Alex Kumar
- Department of Medicine and Physiology, Fribourg, Switzerland.,Department of Primary Care & Public Health Sciences, King's College London, London, United Kingdom
| | - Robert A Atkinson
- Centre for Biomolecular Spectroscopy and Randall Division of Cell and Molecular Biophysics, King's College London Guy's Campus London, London, United Kingdom
| | - David A Green
- Centre of Human and Aerospace Physiological Sciences, King's College London, London, United Kingdom.,KBRwyle, European Astronaut Centre, European Space Agency, Linder Höhe, Cologne, Germany
| | | | - Lindsay M Edwards
- Centre of Human and Aerospace Physiological Sciences, King's College London, London, United Kingdom.,Respiratory Data Sciences Group, Respiratory TAU, GlaxosmithKline Medicines Research, Stevenage, United Kingdom
| | - Steve D R Harridge
- Centre of Human and Aerospace Physiological Sciences, King's College London, London, United Kingdom
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29
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Burtscher M, Niedermeier M, Burtscher J, Pesta D, Suchy J, Strasser B. Preparation for Endurance Competitions at Altitude: Physiological, Psychological, Dietary and Coaching Aspects. A Narrative Review. Front Physiol 2018; 9:1504. [PMID: 30425646 PMCID: PMC6218926 DOI: 10.3389/fphys.2018.01504] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/05/2018] [Indexed: 01/14/2023] Open
Abstract
It was the Summer Olympic Games 1968 held in Mexico City (2,300 m) that required scientists and coaches to cope with the expected decline of performance in endurance athletes and to establish optimal preparation programs for competing at altitude. From that period until now many different recommendations for altitude acclimatization in advance of an altitude competition were proposed, ranging from several hours to several weeks. Those recommendations are mostly based on the separate consideration of the physiology of acclimatization, psychological issues, performance changes, logistical or individual aspects, but there is no review considering all these aspects in their entirety. Therefore, the present work primarily focusses on the period of altitude sojourn prior to the competition at altitude based on physiological and psychological aspects complemented by nutritional and sports practical considerations.
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Affiliation(s)
- Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria.,Austrian Society for Alpine and Mountain Medicine, Innsbruck, Austria
| | - Martin Niedermeier
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Johannes Burtscher
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Dominik Pesta
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University, Düsseldorf, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - Jiri Suchy
- Faculty of Physical Education and Sport, Charles University, Prague, Czechia
| | - Barbara Strasser
- Department of Epidemiology and Preventive Medicine, University of Regensburg, Regensburg, Germany.,Medical School, Sigmund Freud University, Vienna, Austria
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30
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Ferri A, Panariti A, Miserocchi G, Rocchetti M, Buoli Comani G, Rivolta I, Bishop DJ. Tissue specificity of mitochondrial adaptations in rats after 4 weeks of normobaric hypoxia. Eur J Appl Physiol 2018; 118:1641-1652. [PMID: 29855791 DOI: 10.1007/s00421-018-3897-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 05/17/2018] [Indexed: 12/23/2022]
Abstract
PURPOSE Exposure to hypoxia has been suggested to activate multiple adaptive pathways so that muscles are better able to maintain cellular energy homeostasis. However, there is limited research regarding the tissue specificity of this response. The aim of this study was to investigate the influence of tissue specificity on mitochondrial adaptations of rat skeletal and heart muscles after 4 weeks of normobaric hypoxia (FiO2: 0.10). METHODS Twenty male Wistar rats were randomly assigned to either normobaric hypoxia or normoxia. Mitochondrial respiration was determined in permeabilised muscle fibres from left and right ventricles, soleus and extensorum digitorum longus (EDL). Citrate synthase activity and the relative abundance of proteins associated with mitochondrial biogenesis were also analysed. RESULTS After hypoxia exposure, only the soleus and left ventricle (both predominantly oxidative) presented a greater maximal mass-specific respiration (+48 and +25%, p < 0.05) and mitochondrial-specific respiration (+75 and +28%, p < 0.05). Citrate synthase activity was higher in the EDL (0.63 ± 0.08 vs 0.41 ± 0.10 µmol min- 1 µg- 1) and lower in the soleus (0.65 ± 0.17 vs 0.87 ± 0.20 µmol min- 1 µg- 1) in hypoxia with respect to normoxia. There was a lower relative protein abundance of PGC-1α (-25%, p < 0.05) in the right ventricle and a higher relative protein abundance of PGC-1β (+43%, p < 0.05) in the left ventricle of rats exposed to hypoxia, with few differences for protein abundance in the other muscles. CONCLUSION Our results show a muscle-specific response to 4 weeks of normobaric hypoxia. Depending on fibre type, and the presence of ventricular hypertrophy, muscles respond differently to the same degree of environmental hypoxia.
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Affiliation(s)
- Alessandra Ferri
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Alice Panariti
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | | | - Marcella Rocchetti
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
| | - Gaia Buoli Comani
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Ilaria Rivolta
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
| | - David J Bishop
- Institute for Health and Sport, Victoria University, Melbourne, Australia. .,School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia.
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31
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Montero D, Madsen K, Meinild-Lundby AK, Edin F, Lundby C. Sexual dimorphism of substrate utilization: Differences in skeletal muscle mitochondrial volume density and function. Exp Physiol 2018; 103:851-859. [DOI: 10.1113/ep087007] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/04/2018] [Indexed: 01/23/2023]
Affiliation(s)
- David Montero
- Zurich Center for Integrative Human Physiology (ZIHP), Institute of Physiology; University of Zurich; Switzerland
| | - Klavs Madsen
- Department of Food, Nutrition and Sport Science; Gothenburg University; Sweden
| | - Anne-Kristine Meinild-Lundby
- Zurich Center for Integrative Human Physiology (ZIHP), Institute of Physiology; University of Zurich; Switzerland
- Center for Physical Activity Research; University Hospital of Copenhagen; Copenhagen Denmark
| | - Fredrik Edin
- Department of Food, Nutrition and Sport Science; Gothenburg University; Sweden
| | - Carsten Lundby
- Zurich Center for Integrative Human Physiology (ZIHP), Institute of Physiology; University of Zurich; Switzerland
- Department of Food, Nutrition and Sport Science; Gothenburg University; Sweden
- Center for Physical Activity Research; University Hospital of Copenhagen; Copenhagen Denmark
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32
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Dawson NJ, Lyons SA, Henry DA, Scott GR. Effects of chronic hypoxia on diaphragm function in deer mice native to high altitude. Acta Physiol (Oxf) 2018; 223:e13030. [PMID: 29316265 DOI: 10.1111/apha.13030] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/08/2017] [Accepted: 12/31/2017] [Indexed: 12/22/2022]
Abstract
AIM We examined the effects of chronic hypoxia on diaphragm function in high- and low-altitude populations of Peromyscus mice. METHODS Deer mice (P. maniculatus) native to high altitude and congeneric mice native to low altitude (P. leucopus) were born and raised in captivity to adulthood and were acclimated to normoxia or hypobaric hypoxia (12 or 9 kPa, simulating hypoxia at 4300 and 7000 m) for 6-8 weeks. We then measured indices of mitochondrial respiration capacity, force production, and fatigue resistance in the diaphragm. RESULTS Mitochondrial respiratory capacities (assessed using permeabilized fibres with single or multiple inputs to the electron transport system), citrate synthase activity (a marker of mitochondrial volume), twitch force production, and muscle fatigue resistance increased after exposure to chronic hypoxia in both populations. These changes were not well explained by variation in the fibre-type composition of the muscle. However, there were several differences in diaphragm function in high-altitude mice compared to low-altitude mice. Exposure to a deeper level of hypoxia (9 kPa vs 12 kPa) was needed to elicit increases in mitochondrial respiration rates in highlanders. Chronic hypoxia did not increase the emission of reactive oxygen species from permeabilized fibres in highlanders, in contrast to the pronounced increases that occurred in lowlanders. In general, the diaphragm of high-altitude mice had greater capillary length densities, produced less force in response to stimulation and had shorter relaxation times. The latter was associated with higher activity of sarcoplasmic reticulum Ca2+ -ATPase (SERCA) activity in the diaphragm of high-altitude mice. CONCLUSION Overall, our work suggests that exposure to chronic hypoxia increases the capacities for mitochondrial respiration, force production and fatigue resistance of the diaphragm. However, many of these effects are opposed by evolved changes in diaphragm function in high-altitude natives, such that highlanders in chronic hypoxia maintain similar diaphragm function to lowlanders in sea level conditions.
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Affiliation(s)
- N. J. Dawson
- Department of Biology; McMaster University; Hamilton ON Canada
| | - S. A. Lyons
- Department of Biology; McMaster University; Hamilton ON Canada
| | - D. A. Henry
- Department of Biology; McMaster University; Hamilton ON Canada
| | - G. R. Scott
- Department of Biology; McMaster University; Hamilton ON Canada
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33
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Metabolic adjustment to high-altitude hypoxia: from genetic signals to physiological implications. Biochem Soc Trans 2018; 46:599-607. [PMID: 29678953 DOI: 10.1042/bst20170502] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/24/2018] [Accepted: 03/27/2018] [Indexed: 01/04/2023]
Abstract
Ascent to high altitude is associated with physiological responses that counter the stress of hypobaric hypoxia by increasing oxygen delivery and by altering tissue oxygen utilisation via metabolic modulation. At the cellular level, the transcriptional response to hypoxia is mediated by the hypoxia-inducible factor (HIF) pathway and results in promotion of glycolytic capacity and suppression of oxidative metabolism. In Tibetan highlanders, gene variants encoding components of the HIF pathway have undergone selection and are associated with adaptive phenotypic changes, including suppression of erythropoiesis and increased blood lactate levels. In some highland populations, there has also been a selection of variants in PPARA, encoding peroxisome proliferator-activated receptor alpha (PPARα), a transcriptional regulator of fatty acid metabolism. In one such population, the Sherpas, lower muscle PPARA expression is associated with a decreased capacity for fatty acid oxidation, potentially improving the efficiency of oxygen utilisation. In lowlanders ascending to altitude, a similar suppression of fatty acid oxidation occurs, although the underlying molecular mechanism appears to differ along with the consequences. Unlike lowlanders, Sherpas appear to be protected against oxidative stress and the accumulation of intramuscular lipid intermediates at altitude. Moreover, Sherpas are able to defend muscle ATP and phosphocreatine levels in the face of decreased oxygen delivery, possibly due to suppression of ATP demand pathways. The molecular mechanisms allowing Sherpas to successfully live, work and reproduce at altitude may hold the key to novel therapeutic strategies for the treatment of diseases to which hypoxia is a fundamental contributor.
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Salvadego D, Keramidas ME, Kölegård R, Brocca L, Lazzer S, Mavelli I, Rittweger J, Eiken O, Mekjavic IB, Grassi B. PlanHab * : hypoxia does not worsen the impairment of skeletal muscle oxidative function induced by bed rest alone. J Physiol 2018; 596:3341-3355. [PMID: 29665013 DOI: 10.1113/jp275605] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 02/16/2018] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Superposition of hypoxia on 21 day bed rest did not worsen the impairment of skeletal muscle oxidative function induced by bed rest alone. A significant impairment of maximal oxidative performance was identified downstream of cardiovascular O2 delivery, involving both the intramuscular matching between O2 supply and utilization and mitochondrial respiration. These chronic adaptations appear to be relevant in terms of exposure to spaceflights and reduced gravity habitats (Moon or Mars), as characterized by low gravity and hypoxia, in patients with chronic diseases characterized by hypomobility/immobility and hypoxia, as well as in ageing. ABSTRACT Skeletal muscle oxidative function was evaluated in 11 healthy males (mean ± SD age 27 ± 5 years) prior to (baseline data collection, BDC) and following a 21 day horizontal bed rest (BR), carried out in normoxia ( PIO2 = 133 mmHg; N-BR) and hypoxia ( PIO2 = 90 mmHg; H-BR). H-BR was aimed at simulating reduced gravity habitats. The effects of a 21 day hypoxic ambulatory confinement ( PIO2 = 90 mmHg; H-AMB) were also assessed. Pulmonary O2 uptake ( V̇O2 ), vastus lateralis fractional O2 extraction (changes in deoxygenated haemoglobin + myoglobin concentration, Δ[deoxy(Hb + Mb)]; near-infrared spectroscopy) and femoral artery blood flow (ultrasound Doppler) were evaluated during incremental one-leg knee-extension exercise (reduced constraints to cardiovascular O2 delivery) carried out to voluntary exhaustion in a normoxic environment. Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in permeabilized vastus lateralis fibres. V̇O2peak decreased (P < 0.05) after N-BR (0.98 ± 0.13 L min-1 ) and H-BR (0.96 ± 0.17 L min-1 ) vs. BDC (1.05 ± 0.14 L min-1 ). In the presence of a decreased (by ∼6-8%) thigh muscle volume, V̇O2peak normalized per unit of muscle mass was not affected by both interventions. Δ[deoxy(Hb + Mb)]peak decreased (P < 0.05) after N-BR (65 ± 13% of limb ischaemia) and H-BR (62 ± 12%) vs. BDC (73 ± 13%). H-AMB did not alter V̇O2peak or Δ[deoxy(Hb + Mb)]peak . An overshoot of Δ[deoxy(Hb + Mb)] was evident during the first minute of unloaded exercise after N-BR and H-BR. Arterial blood flow to the lower limb during both unloaded and peak knee extension was not affected by any intervention. Maximal ADP-stimulated mitochondrial respiration decreased (P < 0.05) after all interventions vs. control. In 21 day N-BR, a significant impairment of oxidative metabolism occurred downstream of cardiovascular O2 delivery, affecting both mitochondrial respiration and presumably the intramuscular matching between O2 supply and utilization. Superposition of H on BR did not worsen the impairment induced by BR alone.
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Affiliation(s)
- Desy Salvadego
- Department of Medicine, University of Udine, Udine, Italy
| | - Michail E Keramidas
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Roger Kölegård
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Lorenza Brocca
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Stefano Lazzer
- Department of Medicine, University of Udine, Udine, Italy
| | - Irene Mavelli
- Department of Medicine, University of Udine, Udine, Italy
| | - Jörn Rittweger
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, Cologne, Germany
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Bruno Grassi
- Department of Medicine, University of Udine, Udine, Italy.,Institute of Bioimaging and Molecular Physiology, National Research Council, Milano, Italy
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Robach P, Hansen J, Pichon A, Meinild Lundby AK, Dandanell S, Slettaløkken Falch G, Hammarström D, Pesta DH, Siebenmann C, Keiser S, Kérivel P, Whist JE, Rønnestad BR, Lundby C. Hypobaric live high-train low does not improve aerobic performance more than live low-train low in cross-country skiers. Scand J Med Sci Sports 2018; 28:1636-1652. [DOI: 10.1111/sms.13075] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2018] [Indexed: 01/16/2023]
Affiliation(s)
- P. Robach
- Ecole Nationale des Sports de Montagne; site de l'Ecole Nationale de Ski et d'Alpinisme; Chamonix France
- HP2, Université Grenoble Alpes; Grenoble France
| | - J. Hansen
- Inland Norway University of Applied Sciences; Lillehammer Norway
| | - A. Pichon
- Laboratory Mobility, Aging & Exercise (MOVE) - EA 6314; Faculty of Sport Sciences; University of Poitiers; Poitiers France
| | - A.-K. Meinild Lundby
- The Centre for Physical Activity Research; University Hospital of Copenhagen; Copenhagen Denmark
| | - S. Dandanell
- Center for Healthy Aging; Department of Biomedical Sciences; XLab; University of Copenhagen; Copenhagen Denmark
- Department for Physiotherapy and Occupational Therapy; Metropolitan University College; Copenhagen Denmark
| | | | - D. Hammarström
- Inland Norway University of Applied Sciences; Lillehammer Norway
| | - D. H. Pesta
- Department of Sport Science; Faculty for Sports Science and Psychology; University of Innsbruck; Innsbruck Austria
- Department of Visceral, Transplant, and Thoracic Surgery; D. Swarovski Research Laboratory; Medical University of Innsbruck; Innsbruck Austria
| | - C. Siebenmann
- The Centre for Physical Activity Research; University Hospital of Copenhagen; Copenhagen Denmark
| | - S. Keiser
- Institute of Physiology; University of Zürich; Zürich Switzerland
| | - P. Kérivel
- Ecole Nationale des Sports de Montagne; site de l'Ecole Nationale de Ski et d'Alpinisme; Chamonix France
| | - J. E. Whist
- Innlandet Hospital Trust; Lillehammer Norway
| | - B. R. Rønnestad
- Inland Norway University of Applied Sciences; Lillehammer Norway
| | - C. Lundby
- The Centre for Physical Activity Research; University Hospital of Copenhagen; Copenhagen Denmark
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Chicco AJ, Le CH, Gnaiger E, Dreyer HC, Muyskens JB, D'Alessandro A, Nemkov T, Hocker AD, Prenni JE, Wolfe LM, Sindt NM, Lovering AT, Subudhi AW, Roach RC. Adaptive remodeling of skeletal muscle energy metabolism in high-altitude hypoxia: Lessons from AltitudeOmics. J Biol Chem 2018. [PMID: 29540485 DOI: 10.1074/jbc.ra117.000470] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Metabolic responses to hypoxia play important roles in cell survival strategies and disease pathogenesis in humans. However, the homeostatic adjustments that balance changes in energy supply and demand to maintain organismal function under chronic low oxygen conditions remain incompletely understood, making it difficult to distinguish adaptive from maladaptive responses in hypoxia-related pathologies. We integrated metabolomic and proteomic profiling with mitochondrial respirometry and blood gas analyses to comprehensively define the physiological responses of skeletal muscle energy metabolism to 16 days of high-altitude hypoxia (5260 m) in healthy volunteers from the AltitudeOmics project. In contrast to the view that hypoxia down-regulates aerobic metabolism, results show that mitochondria play a central role in muscle hypoxia adaptation by supporting higher resting phosphorylation potential and enhancing the efficiency of long-chain acylcarnitine oxidation. This directs increases in muscle glucose toward pentose phosphate and one-carbon metabolism pathways that support cytosolic redox balance and help mitigate the effects of increased protein and purine nucleotide catabolism in hypoxia. Muscle accumulation of free amino acids favor these adjustments by coordinating cytosolic and mitochondrial pathways to rid the cell of excess nitrogen, but might ultimately limit muscle oxidative capacity in vivo Collectively, these studies illustrate how an integration of aerobic and anaerobic metabolism is required for physiological hypoxia adaptation in skeletal muscle, and highlight protein catabolism and allosteric regulation as unexpected orchestrators of metabolic remodeling in this context. These findings have important implications for the management of hypoxia-related diseases and other conditions associated with chronic catabolic stress.
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Affiliation(s)
- Adam J Chicco
- From the Departments of Biomedical Sciences, .,Cell and Molecular Biology, and
| | | | - Erich Gnaiger
- the Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Hans C Dreyer
- the Department of Human Physiology, University of Oregon, Eugene, Oregon 97403-1240, and
| | - Jonathan B Muyskens
- the Department of Human Physiology, University of Oregon, Eugene, Oregon 97403-1240, and
| | | | - Travis Nemkov
- the Department of Biochemistry and Molecular Genetics and
| | - Austin D Hocker
- the Department of Human Physiology, University of Oregon, Eugene, Oregon 97403-1240, and
| | - Jessica E Prenni
- Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Lisa M Wolfe
- Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Nathan M Sindt
- Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Andrew T Lovering
- the Department of Human Physiology, University of Oregon, Eugene, Oregon 97403-1240, and
| | - Andrew W Subudhi
- the Department of Biology, University of Colorado, Colorado Springs, Colorado 80918
| | - Robert C Roach
- Altitude Research Center, University of Colorado-Anschutz Medical Campus, Aurora 80045, Colorado 80045
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Pamenter ME, Lau GY, Richards JG, Milsom WK. Naked mole rat brain mitochondria electron transport system flux and H + leak are reduced during acute hypoxia. ACTA ACUST UNITED AC 2018; 221:jeb.171397. [PMID: 29361591 DOI: 10.1242/jeb.171397] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/19/2017] [Indexed: 01/02/2023]
Abstract
Mitochondrial respiration and ATP production are compromised by hypoxia. Naked mole rats (NMRs) are among the most hypoxia-tolerant mammals and reduce metabolic rate in hypoxic environments; however, little is known regarding mitochondrial function during in vivo hypoxia exposure in this species. To address this knowledge gap, we asked whether the function of NMR brain mitochondria exhibits metabolic plasticity during acute hypoxia. Respirometry was utilized to assess whole-animal oxygen consumption rates and high-resolution respirometry was utilized to assess electron transport system (ETS) function in saponin-permeabilized NMR brain. We found that NMR whole-animal oxygen consumption rate reversibly decreased by ∼85% in acute hypoxia (4 h at 3% O2). Similarly, relative to untreated controls, permeabilized brain respiratory flux through the ETS was decreased by ∼90% in acutely hypoxic animals. Relative to carbonyl cyanide p-trifluoro-methoxyphenylhydrazone-uncoupled total ETS flux, this functional decrease was observed equally across all components of the ETS except for complex IV (cytochrome c oxidase), at which flux was further reduced, supporting a regulatory role for this enzyme during acute hypoxia. The maximum enzymatic capacities of ETS complexes I-V were not altered by acute hypoxia; however, the mitochondrial H+ gradient decreased in step with the decrease in ETS respiration. Taken together, our results indicate that NMR brain ETS flux and H+ leak are reduced in a balanced and regulated fashion during acute hypoxia. Changes in NMR mitochondrial metabolic plasticity mirror whole-animal metabolic responses to hypoxia.
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Affiliation(s)
- Matthew E Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N5 .,Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
| | - Gigi Y Lau
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Jeffrey G Richards
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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Konopka AR, Castor WM, Wolff CA, Musci RV, Reid JJ, Laurin JL, Valenti ZJ, Hamilton KL, Miller BF. Skeletal muscle mitochondrial protein synthesis and respiration in response to the energetic stress of an ultra-endurance race. J Appl Physiol (1985) 2017; 123:1516-1524. [PMID: 28883046 DOI: 10.1152/japplphysiol.00457.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The 2016 Colorado Trail Race (CTR) was an ultra-endurance mountain bike race in which competitors cycled for up to 24 h/day between altitudes of 1,675 and 4,025 m to complete 800 km and 21,000 m of elevation gain. In one athlete, we had the unique opportunity to characterize skeletal muscle protein synthesis and mitochondrial respiration in response to a normal activity control period (CON) and the CTR. We hypothesized that mitochondrial protein synthesis would be elevated and mitochondrial respiration would be maintained during the extreme stresses of the CTR. Titrated and bolus doses of ADP were provided to determine substrate-specific oxidative phosphorylation (OXPHOS) and electron transport system (ETS) capacities in permeabilized muscle fibers via high-resolution respirometry. Protein synthetic rates were determined by daily oral consumption of deuterium oxide (2H2O). The endurance athlete had OXPHOS (226 pmol·s-1·mg tissue-1) and ETS (231 pmol·s-1·mg tissue-1) capacities that rank among the highest published to date in humans. Mitochondrial (3.2-fold), cytoplasmic (2.3-fold), and myofibrillar (1.5-fold) protein synthesis rates were greater during CTR compared with CON. With titrated ADP doses, the apparent Km of ADP, OXPHOS, and ETS increased after the CTR. With provision of ADP boluses after the CTR, the addition of fatty acids (-12 and -14%) mitigated the decline in OXPHOS and ETS capacity during carbohydrate-supported respiration (-26 and -31%). In the face of extreme stresses during the CTR, elevated rates of mitochondrial protein synthesis may contribute to rapid adaptations in mitochondrial bioenergetics. NEW & NOTEWORTHY The mechanisms that maintain skeletal muscle function during extreme stresses remain incompletely understood. In the current study, greater rates of mitochondrial protein synthesis during the energetic demands of ultra-endurance exercise may contribute to rapid adaptations in mitochondrial bioenergetics. The endurance athlete herein achieved mitochondrial respiratory capacities among the highest published for humans. Greater mitochondrial protein synthesis during ultra-endurance exercise may contribute to improved mitochondrial respiration and serve as a mechanism to resist cellular energetic stresses.
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Affiliation(s)
- Adam R Konopka
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado.,Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign , Urbana, Illinois
| | - William M Castor
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
| | - Christopher A Wolff
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
| | - Robert V Musci
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
| | - Justin J Reid
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
| | - Jaime L Laurin
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
| | - Zackary J Valenti
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
| | - Karyn L Hamilton
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
| | - Benjamin F Miller
- Department of Health and Exercise Science, Colorado State University Fort Collins, Colorado
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Mahalingam S, McClelland GB, Scott GR. Evolved changes in the intracellular distribution and physiology of muscle mitochondria in high-altitude native deer mice. J Physiol 2017; 595:4785-4801. [PMID: 28418073 DOI: 10.1113/jp274130] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/12/2017] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Mitochondrial function changes over time at high altitudes, but the potential benefits of these changes for hypoxia resistance remains unclear. We used high-altitude-adapted populations of deer mice, which exhibit enhanced aerobic performance in hypoxia, to examine whether changes in mitochondrial physiology or intracellular distribution in the muscle contribute to hypoxia resistance. Permeabilized muscle fibres from the gastrocnemius muscle had higher respiratory capacities in high-altitude mice than in low-altitude mice. Highlanders also had higher mitochondrial volume densities, due entirely to an enriched abundance of subsarcolemmal mitochondria, such that more mitochondria were situated near the cell membrane and adjacent to capillaries. There were several effects of hypoxia acclimation on mitochondrial function, some of which were population specific, but they differed from the evolved changes in high-altitude natives, which probably provide a better indication of adaptive traits that improve performance and hypoxia resistance at high altitudes. ABSTRACT High-altitude natives that have evolved to live in hypoxic environments provide a compelling system to understand how animals can overcome impairments in oxygen availability. We examined whether these include changes in mitochondrial physiology or intracellular distribution that contribute to hypoxia resistance in high-altitude deer mice (Peromyscus maniculatus). Mice from populations native to high and low altitudes were born and raised in captivity, and as adults were acclimated to normoxia or hypobaric hypoxia (equivalent to 4300 m elevation). We found that highlanders had higher respiratory capacities in the gastrocnemius (but not soleus) muscle than lowlanders (assessed using permeabilized fibres with single or multiple inputs to the electron transport system), due in large part to higher mitochondrial volume densities in the gastrocnemius. The latter was attributed to an increased abundance of subsarcolemmal (but not intermyofibrillar) mitochondria, such that more mitochondria were situated near the cell membrane and adjacent to capillaries. Hypoxia acclimation had no significant effect on these population differences, but it did increase mitochondrial cristae surface densities of mitochondria in both populations. Hypoxia acclimation also altered the physiology of isolated mitochondria by affecting respiratory capacities and cytochrome c oxidase activities in population-specific manners. Chronic hypoxia decreased the release of reactive oxygen species by isolated mitochondria in both populations. There were subtle differences in O2 kinetics between populations, with highlanders exhibiting increased mitochondrial O2 affinity or catalytic efficiency in some conditions. Our results suggest that evolved changes in mitochondrial physiology in high-altitude natives are distinct from the effects of hypoxia acclimation, and probably provide a better indication of adaptive traits that improve performance and hypoxia resistance at high altitudes.
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Affiliation(s)
- Sajeni Mahalingam
- Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1
| | - Grant B McClelland
- Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1
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Abstract
The Himalayan Sherpas, a human population of Tibetan descent, are highly adapted to life in the hypobaric hypoxia of high altitude. Mechanisms involving enhanced tissue oxygen delivery in comparison to Lowlander populations have been postulated to play a role in such adaptation. Whether differences in tissue oxygen utilization (i.e., metabolic adaptation) underpin this adaptation is not known, however. We sought to address this issue, applying parallel molecular, biochemical, physiological, and genetic approaches to the study of Sherpas and native Lowlanders, studied before and during exposure to hypobaric hypoxia on a gradual ascent to Mount Everest Base Camp (5,300 m). Compared with Lowlanders, Sherpas demonstrated a lower capacity for fatty acid oxidation in skeletal muscle biopsies, along with enhanced efficiency of oxygen utilization, improved muscle energetics, and protection against oxidative stress. This adaptation appeared to be related, in part, to a putatively advantageous allele for the peroxisome proliferator-activated receptor A (PPARA) gene, which was enriched in the Sherpas compared with the Lowlanders. Our findings suggest that metabolic adaptations underpin human evolution to life at high altitude, and could have an impact upon our understanding of human diseases in which hypoxia is a feature.
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Lundby C, Montero D, Gehrig S, Andersson Hall U, Kaiser P, Boushel R, Meinild Lundby AK, Kirk N, Valdivieso P, Flück M, Secher NH, Edin F, Hein T, Madsen K. Physiological, biochemical, anthropometric, and biomechanical influences on exercise economy in humans. Scand J Med Sci Sports 2017; 27:1627-1637. [DOI: 10.1111/sms.12849] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2017] [Indexed: 01/27/2023]
Affiliation(s)
- C. Lundby
- Department of Food & Nutrition & Sport Science; Gothenburg University; Gothenburg Sweden
- Zürich Center for Integrative Human Physiology (ZIHP); University of Zürich; Zürich Switzerland
| | - D. Montero
- Zürich Center for Integrative Human Physiology (ZIHP); University of Zürich; Zürich Switzerland
| | - S. Gehrig
- Zürich Center for Integrative Human Physiology (ZIHP); University of Zürich; Zürich Switzerland
| | - U. Andersson Hall
- Department of Food & Nutrition & Sport Science; Gothenburg University; Gothenburg Sweden
| | - P. Kaiser
- Zürich Center for Integrative Human Physiology (ZIHP); University of Zürich; Zürich Switzerland
| | - R. Boushel
- School of Kinesiology; University of British Columbia; Vancouver Canada
| | - A.-K. Meinild Lundby
- Zürich Center for Integrative Human Physiology (ZIHP); University of Zürich; Zürich Switzerland
| | - N. Kirk
- Zürich Center for Integrative Human Physiology (ZIHP); University of Zürich; Zürich Switzerland
| | | | - M. Flück
- Universitätsklinik Balgrist; Zürich Switzerland
| | - N. H. Secher
- Department of Anesthesia; The Copenhagen Muscle Research Center; Rigshospitalet; University of Copenhagen; Copenhagen Denmark
| | - F. Edin
- Department of Food & Nutrition & Sport Science; Gothenburg University; Gothenburg Sweden
| | - T. Hein
- Department of Food & Nutrition & Sport Science; Gothenburg University; Gothenburg Sweden
| | - K. Madsen
- Department of Food & Nutrition & Sport Science; Gothenburg University; Gothenburg Sweden
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Reduced cancer mortality at high altitude: The role of glucose, lipids, iron and physical activity. Exp Cell Res 2017; 356:209-216. [PMID: 28344053 DOI: 10.1016/j.yexcr.2017.03.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 03/22/2017] [Indexed: 12/21/2022]
Abstract
Residency at high altitude (HA) demands adaptation to challenging environmental conditions with hypobaric hypoxia being the most important one. Epidemiological and experimental data suggest that chronic exposure to HA reduces cancer mortality and lowers prevalence of metabolic disorders like diabetes and obesity implying that adaption to HA modifies a broad spectrum of physiological, metabolic and cellular programs with a generally beneficial outcome for humans. However, the complexity of multiple, potentially tumor-suppressive pathways at HA impedes the understanding of mechanisms leading to reduced cancer mortality. Many adaptive processes at HA are tightly interconnected and thus it cannot be ruled out that the entirety or at least some of the HA-related alterations act in concert to reduce cancer mortality. In this review we discuss tumor formation as a concept of competition between healthy and cancer cells with improved fitness - and therefore higher competitiveness - of healthy cells at high altitude. We discuss HA-related changes in glucose, lipid and iron metabolism that may have an impact on tumorigenesis. Additionally, we discuss two parameters with a strong impact on tumorigenesis, namely drug metabolism and physical activity, to underpin their potential contribution to HA-dependent reduced cancer mortality. Future studies are needed to unravel why cancer mortality is reduced at HA and how this knowledge might be used to prevent and to treat cancer patients.
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Malgoyre A, Chabert C, Tonini J, Koulmann N, Bigard X, Sanchez H. Alterations to mitochondrial fatty-acid use in skeletal muscle after chronic exposure to hypoxia depend on metabolic phenotype. J Appl Physiol (1985) 2017; 122:666-674. [DOI: 10.1152/japplphysiol.00090.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 12/21/2016] [Accepted: 12/22/2016] [Indexed: 01/01/2023] Open
Abstract
We investigated the effects of chronic hypoxia on the maximal use of and sensitivity of mitochondria to different substrates in rat slow-oxidative (soleus, SOL) and fast-glycolytic (extensor digitorum longus, EDL) muscles. We studied mitochondrial respiration in situ in permeabilized myofibers, using pyruvate, octanoate, palmitoyl-carnitine (PC), or palmitoyl-coenzyme A (PCoA). The hypophagia induced by hypoxia may also alter metabolism. Therefore, we used a group of pair-fed rats (reproducing the same caloric restriction, as observed in hypoxic animals), in addition to the normoxic control fed ad libitum. The resting respiratory exchange ratio decreased after 21 days of exposure to hypobaric hypoxia (simulated elevation of 5,500 m). The respiration supported by pyruvate and octanoate were unaffected. In contrast, the maximal oxidative respiratory rate for PCoA, the transport of which depends on carnitine palmitoyltransferase 1 (CPT-1), decreased in the rapid-glycolytic EDL and increased in the slow-oxidative SOL, although hypoxia improved affinity for this substrate in both muscle types. PC and PCoA were oxidized similarly in normoxic EDL, whereas chronic hypoxia limited transport at the CPT-1 step in this muscle. The effects of hypoxia were mediated by caloric restriction in the SOL and by hypoxia itself in the EDL. We conclude that improvements in mitochondrial affinity for PCoA, a physiological long-chain fatty acid, would facilitate fatty-acid use at rest after chronic hypoxia independently of quantitative alterations of mitochondria. Conversely, decreasing the maximal oxidation of PCoA in fast-glycolytic muscles would limit fatty-acid use during exercise. NEW & NOTEWORTHY Affinity for low concentrations of long-chain fatty acids (LCFA) in mitochondria skeletal muscles increases after chronic hypoxia. Combined with a lower respiratory exchange ratio, this suggests facility for fatty acid utilization at rest. This fuel preference is related to caloric restriction in oxidative muscle and to hypoxia in glycolytic one. In contrast, maximal oxidation for LCFA is decreased by chronic hypoxia in glycolytic muscle and can explain glucose dependence at exercise.
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Affiliation(s)
- Alexandra Malgoyre
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Clovis Chabert
- Laboratoire de Bioénergétique Fondamentale et Appliquée, Université Joseph Fourier and Institut National de la Santé et de la Recherche Médicale U1055, Grenoble France
| | - Julia Tonini
- Centre de Recherche du Service de Santé des Armées, La Tronche, La Tronche, France; and
| | - Nathalie Koulmann
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
- Ecole du Val de Grâce, Paris, France
| | - Xavier Bigard
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
- Ecole du Val de Grâce, Paris, France
| | - Hervé Sanchez
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
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Siebenmann C, Rasmussen P, Hug M, Keiser S, Flück D, Fisher JP, Hilty MP, Maggiorini M, Lundby C. Parasympathetic withdrawal increases heart rate after 2 weeks at 3454 m altitude. J Physiol 2017; 595:1619-1626. [PMID: 27966225 DOI: 10.1113/jp273726] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 11/21/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Heart rate is increased in chronic hypoxia and we tested whether this is the result of increased sympathetic nervous activity, reduced parasympathetic nervous activity, or a non-autonomic mechanism. In seven lowlanders, heart rate was measured at sea level and after 2 weeks at high altitude after individual and combined pharmacological inhibition of sympathetic and/or parasympathetic control of the heart. Inhibition of parasympathetic control of the heart alone or in combination with inhibition of sympathetic control abolished the high altitude-induced increase in heart rate. Inhibition of sympathetic control of the heart alone did not prevent the high altitude-induced increase in heart rate. These results indicate that a reduced parasympathetic nervous activity is the main mechanism underlying the elevated heart rate in chronic hypoxia. ABSTRACT Chronic hypoxia increases resting heart rate (HR), but the underlying mechanism remains incompletely understood. We investigated the relative contributions of the sympathetic and parasympathetic nervous systems, along with potential non-autonomic mechanisms, by individual and combined pharmacological inhibition of muscarinic and/or β-adrenergic receptors. In seven healthy lowlanders, resting HR was determined at sea level (SL) and after 15-18 days of exposure to 3454 m high altitude (HA) without drug intervention (control, CONT) as well as after intravenous administration of either propranolol (PROP), or glycopyrrolate (GLYC), or PROP and GLYC in combination (PROP+GLYC). Circulating noradrenaline concentration increased from 0.9 ± 0.4 nmol l-1 at SL to 2.7 ± 1.5 nmol l-1 at HA (P = 0.03). The effect of HA on HR depended on the type of autonomic inhibition (P = 0.006). Specifically, HR was increased at HA from 64 ± 10 to 74 ± 12 beats min-1 during the CONT treatment (P = 0.007) and from 52 ± 4 to 59 ± 5 beats min-1 during the PROP treatment (P < 0.001). In contrast, HR was similar between SL and HA during the GLYC treatment (110 ± 7 and 112 ± 5 beats min-1 , P = 0.28) and PROP+GLYC treatment (83 ± 5 and 85 ± 5 beats min-1 , P = 0.25). Our results identify a reduction in cardiac parasympathetic activity as the primary mechanism underlying the elevated HR associated with 2 weeks of exposure to hypoxia. Unexpectedly, the sympathoactivation at HA that was evidenced by increased circulating noradrenaline concentration had little effect on HR, potentially reflecting down-regulation of cardiac β-adrenergic receptor function in chronic hypoxia. These effects of chronic hypoxia on autonomic control of the heart may concern not only HA dwellers, but also patients with disorders that are associated with hypoxaemia.
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Affiliation(s)
- Christoph Siebenmann
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland.,Department of Environmental Physiology, School of Technology and Health, Royal Institute of Technology, Solna, Sweden
| | - Peter Rasmussen
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland.,H. Lundbeck A/S, Valby, Denmark
| | - Mike Hug
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Stefanie Keiser
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Daniela Flück
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - James P Fisher
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Matthias P Hilty
- Intensive Care Unit, University Hospital of Zürich, Zürich, Switzerland
| | - Marco Maggiorini
- Intensive Care Unit, University Hospital of Zürich, Zürich, Switzerland
| | - Carsten Lundby
- Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
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Tyrrell DJ, Bharadwaj MS, Jorgensen MJ, Register TC, Molina AJA. Blood cell respirometry is associated with skeletal and cardiac muscle bioenergetics: Implications for a minimally invasive biomarker of mitochondrial health. Redox Biol 2016; 10:65-77. [PMID: 27693859 PMCID: PMC5045569 DOI: 10.1016/j.redox.2016.09.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 09/20/2016] [Indexed: 12/15/2022] Open
Abstract
Blood based bioenergetic profiling strategies are emerging as potential reporters of systemic mitochondrial function; however, the extent to which these measures reflect the bioenergetic capacity of other tissues is not known. The premise of this work is that highly metabolically active tissues, such as skeletal and cardiac muscle, are susceptible to differences in systemic bioenergetic capacity. Therefore, we tested whether the respiratory capacity of blood cells, monocytes and platelets, are related to contemporaneous respirometric assessments of skeletal and cardiac muscle mitochondria. 18 female vervet/African green monkeys (Chlorocebus aethiops sabaeus) of varying age and metabolic status were examined for this study. Monocyte and platelet maximal capacity correlated with maximal oxidative phosphorylation capacity of permeabilized skeletal muscle (R=0.75, 95% confidence interval [CI]: 0.38-0.97; R=0.51, 95%CI: 0.05-0.81; respectively), isolated skeletal muscle mitochondrial respiratory control ratio (RCR; R=0.70, 95%CI: 0.35-0.89; R=0.64, 95%CI: 0.23-0.98; respectively), and isolated cardiac muscle mitochondrial RCR (R=0.55, 95%CI: 0.22-0.86; R=0.58, 95%CI: 0.22-0.85; respectively). These results suggest that blood based bioenergetic profiling may be used to report on the bioenergetic capacity of muscle tissues. Blood cell respirometry represents an attractive alternative to tissue based assessments of mitochondrial function in human studies based on ease of access and the minimal participant burden required by these measures.
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Affiliation(s)
- Daniel J Tyrrell
- Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Manish S Bharadwaj
- Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Matthew J Jorgensen
- Department of Pathology, Section on Comparative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Thomas C Register
- Department of Pathology, Section on Comparative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Anthony J A Molina
- Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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46
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Salin K, Auer SK, Rudolf AM, Anderson GJ, Selman C, Metcalfe NB. Variation in Metabolic Rate among Individuals Is Related to Tissue-Specific Differences in Mitochondrial Leak Respiration. Physiol Biochem Zool 2016; 89:511-523. [DOI: 10.1086/688769] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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47
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Gehrig SM, Mihaylova V, Frese S, Mueller SM, Ligon-Auer M, Spengler CM, Petersen JA, Lundby C, Jung HH. Altered skeletal muscle (mitochondrial) properties in patients with mitochondrial DNA single deletion myopathy. Orphanet J Rare Dis 2016; 11:105. [PMID: 27473873 PMCID: PMC4966582 DOI: 10.1186/s13023-016-0488-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 07/21/2016] [Indexed: 12/13/2022] Open
Abstract
Background Mitochondrial myopathy severely affects skeletal muscle structure and function resulting in defective oxidative phosphorylation. However, the major pathomechanisms and therewith effective treatment approaches remain elusive. Therefore, the aim of the present study was to investigate disease-related impairments in skeletal muscle properties in patients with mitochondrial myopathy. Accordingly, skeletal muscle biopsies were obtained from six patients with moleculargenetically diagnosed mitochondrial myopathy (one male and five females, 53 ± 9 years) and eight age- and gender-matched healthy controls (two males and six females, 58 ± 14 years) to determine mitochondrial respiratory capacity of complex I-V, mitochondrial volume density and fiber type distribution. Results Mitochondrial volume density (4.0 ± 0.5 vs. 5.1 ± 0.8 %) as well as respiratory capacity of complex I-V were lower (P < 0.05) in mitochondrial myopathy and associated with a higher (P < 0.001) proportion of type II fibers (65.2 ± 3.6 vs. 44.3 ± 5.9 %). Additionally, mitochondrial volume density and maximal oxidative phosphorylation capacity correlated positively (P < 0.05) to peak oxygen uptake. Conclusion Mitochondrial myopathy leads to impaired mitochondrial quantity and quality and a shift towards a more glycolytic skeletal muscle phenotype.
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Affiliation(s)
- Saskia Maria Gehrig
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland.,Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Violeta Mihaylova
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland
| | - Sebastian Frese
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland
| | - Sandro Manuel Mueller
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland
| | - Maria Ligon-Auer
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland
| | - Christina M Spengler
- Zurich Center for Integrative Human Physiology (ZIHP), Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Exercise Physiology Lab, Institute of Human Movement Sciences, ETH Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Jens A Petersen
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland
| | - Carsten Lundby
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Hans H Jung
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland. .,Zurich Center for Integrative Human Physiology (ZIHP), Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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48
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Keramidas ME, Kölegård R, Mekjavic IB, Eiken O. PlanHab: hypoxia exaggerates the bed-rest-induced reduction in peak oxygen uptake during upright cycle ergometry. Am J Physiol Heart Circ Physiol 2016; 311:H453-64. [PMID: 27342877 DOI: 10.1152/ajpheart.00304.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 06/20/2016] [Indexed: 11/22/2022]
Abstract
The study examined the effects of hypoxia and horizontal bed rest, separately and in combination, on peak oxygen uptake (V̇o2 peak) during upright cycle ergometry. Ten male lowlanders underwent three 21-day confinement periods in a counterbalanced order: 1) normoxic bed rest [NBR; partial pressure of inspired O2 (PiO2 ) = 133.1 ± 0.3 mmHg]; 2) hypoxic bed rest (HBR; PiO2 = 90.0 ± 0.4 mmHg), and 3) hypoxic ambulation (HAMB; PiO2 = 90.0 ± 0.4 mmHg). Before and after each confinement, subjects performed two incremental-load trials to exhaustion, while inspiring either room air (AIR), or a hypoxic gas (HYPO; PiO2 = 90.0 ± 0.4 mmHg). Changes in regional oxygenation of the vastus lateralis muscle and the frontal cerebral cortex were monitored with near-infrared spectroscopy. Cardiac output (CO) was recorded using a bioimpedance method. The AIR V̇o2 peak was decreased by both HBR (∼13.5%; P ≤ 0.001) and NBR (∼8.6%; P ≤ 0.001), with greater drop after HBR (P = 0.01). The HYPO V̇o2 peak was also reduced by HBR (-9.7%; P ≤ 0.001) and NBR (-6.1%; P ≤ 0.001). Peak CO was lower after both bed-rest interventions, and especially after HBR (HBR: ∼13%, NBR: ∼7%; P ≤ 0.05). Exercise-induced alterations in muscle and cerebral oxygenation were blunted in a similar manner after both bed-rest confinements. No changes were observed in HAMB. Hence, the bed-rest-induced decrease in V̇o2 peak was exaggerated by hypoxia, most likely due to a reduction in convective O2 transport, as indicated by the lower peak values of CO.
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Affiliation(s)
- Michail E Keramidas
- Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden;
| | - Roger Kölegård
- Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia; and Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden
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49
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Christensen PM, Jacobs RA, Bonne T, Flück D, Bangsbo J, Lundby C. A short period of high-intensity interval training improves skeletal muscle mitochondrial function and pulmonary oxygen uptake kinetics. J Appl Physiol (1985) 2016; 120:1319-27. [PMID: 26846547 DOI: 10.1152/japplphysiol.00115.2015] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 02/02/2016] [Indexed: 11/22/2022] Open
Abstract
The aim of the present study was to examine whether improvements in pulmonary oxygen uptake (V̇o2) kinetics following a short period of high-intensity training (HIT) would be associated with improved skeletal muscle mitochondrial function. Ten untrained male volunteers (age 26 ± 2 yr; mean ± SD) performed six HIT sessions (8-12 × 60 s at incremental test peak power; 271 ± 52 W) over a 2-wk period. Before and after the HIT period, V̇o2 kinetics was modeled during moderate-intensity cycling (110 ± 19 W). Mitochondrial function was assessed with high-resolution respirometry (HRR), and maximal activities of oxidative enzymes citrate synthase (CS) and cytochrome c oxidase (COX) were accordingly determined. In response to HIT, V̇o2 kinetics became faster (τ: 20.4 ± 4.4 vs. 28.9 ± 6.1 s; P < 0.01) and fatty acid oxidation (ETFP) and leak respiration (LN) both became elevated (P < 0.05). Activity of CS and COX did not increase in response to training. Both before and after the HIT period, fast V̇o2 kinetics (low τ values) was associated with large values for ETFP, electron transport system capacity (ETS), and electron flow specific to complex II (CIIP) (P < 0.05). Collectively, these findings support that selected measures of mitochondrial function obtained with HRR are important for fast V̇o2 kinetics and better markers than maximal oxidative enzyme activity in describing the speed of the V̇o2 response during moderate-intensity exercise.
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Affiliation(s)
- Peter M Christensen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; Team Danmark (Danish Elite Sport Organization), Copenhagen, Denmark
| | - Robert A Jacobs
- Health and Physical Education, School of Teaching and Learning, Western Carolina University, Cullowhee, North Carolina; Department of Physical Therapy, Western Carolina University, Cullowhee, North Carolina; and
| | - Thomas Bonne
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Daniela Flück
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Carsten Lundby
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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50
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Ashmore T, Roberts LD, Morash AJ, Kotwica AO, Finnerty J, West JA, Murfitt SA, Fernandez BO, Branco C, Cowburn AS, Clarke K, Johnson RS, Feelisch M, Griffin JL, Murray AJ. Nitrate enhances skeletal muscle fatty acid oxidation via a nitric oxide-cGMP-PPAR-mediated mechanism. BMC Biol 2015; 13:110. [PMID: 26694920 PMCID: PMC4688964 DOI: 10.1186/s12915-015-0221-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 12/10/2015] [Indexed: 02/07/2023] Open
Abstract
Background Insulin sensitivity in skeletal muscle is associated with metabolic flexibility, including a high capacity to increase fatty acid (FA) oxidation in response to increased lipid supply. Lipid overload, however, can result in incomplete FA oxidation and accumulation of potentially harmful intermediates where mitochondrial tricarboxylic acid cycle capacity cannot keep pace with rates of β-oxidation. Enhancement of muscle FA oxidation in combination with mitochondrial biogenesis is therefore emerging as a strategy to treat metabolic disease. Dietary inorganic nitrate was recently shown to reverse aspects of the metabolic syndrome in rodents by as yet incompletely defined mechanisms. Results Herein, we report that nitrate enhances skeletal muscle FA oxidation in rodents in a dose-dependent manner. We show that nitrate induces FA oxidation through a soluble guanylate cyclase (sGC)/cGMP-mediated PPARβ/δ- and PPARα-dependent mechanism. Enhanced PPARβ/δ and PPARα expression and DNA binding induces expression of FA oxidation enzymes, increasing muscle carnitine and lowering tissue malonyl-CoA concentrations, thereby supporting intra-mitochondrial pathways of FA oxidation and enhancing mitochondrial respiration. At higher doses, nitrate induces mitochondrial biogenesis, further increasing FA oxidation and lowering long-chain FA concentrations. Meanwhile, nitrate did not affect mitochondrial FA oxidation in PPARα−/− mice. In C2C12 myotubes, nitrate increased expression of the PPARα targets Cpt1b, Acadl, Hadh and Ucp3, and enhanced oxidative phosphorylation rates with palmitoyl-carnitine; however, these changes in gene expression and respiration were prevented by inhibition of either sGC or protein kinase G. Elevation of cGMP, via the inhibition of phosphodiesterase 5 by sildenafil, also increased expression of Cpt1b, Acadl and Ucp3, as well as CPT1B protein levels, and further enhanced the effect of nitrate supplementation. Conclusions Nitrate may therefore be effective in the treatment of metabolic disease by inducing FA oxidation in muscle. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0221-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tom Ashmore
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.,Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Lee D Roberts
- Department of Biochemistry, University of Cambridge, Cambridge, UK.,MRC-Human Nutrition Research, University of Cambridge, Cambridge, UK
| | - Andrea J Morash
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Aleksandra O Kotwica
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - John Finnerty
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - James A West
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Steven A Murfitt
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Bernadette O Fernandez
- Faculty of Medicine, Clinical & Experimental Sciences, University of Southampton, Southampton, UK
| | - Cristina Branco
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Andrew S Cowburn
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
| | - Randall S Johnson
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Martin Feelisch
- Faculty of Medicine, Clinical & Experimental Sciences, University of Southampton, Southampton, UK
| | - Julian L Griffin
- Department of Biochemistry, University of Cambridge, Cambridge, UK.,MRC-Human Nutrition Research, University of Cambridge, Cambridge, UK
| | - Andrew J Murray
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.
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