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Royal JT, Eiken O, Keramidas ME, McDonnell AC, Mekjavic IB. Heterogeneity of Hematological Response to Hypoxia and Short-Term or Medium-Term Bed Rest. Front Physiol 2021; 12:777611. [PMID: 34975531 PMCID: PMC8715762 DOI: 10.3389/fphys.2021.777611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 11/16/2021] [Indexed: 11/30/2022] Open
Abstract
Hematological changes are commonly observed following prolonged exposure to hypoxia and bed rest. Typically, such responses have been reported as means and standard deviations, however, investigation into the responses of individuals is insufficient. Therefore, the present study retrospectively assessed individual variation in the hematological responses to severe inactivity (bed rest) and hypoxia. The data were derived from three-bed rest projects: two 10-d (LunHab project: 8 males; FemHab project: 12 females), and one 21-d (PlanHab project: 11 males). Each project comprised a normoxic bed rest (NBR; PIO2=133mmHg) and hypoxic bed rest (HBR; PIO2=91mmHg) intervention, where the subjects were confined in the Planica facility (Rateče, Slovenia). During the HBR intervention, subjects were exposed to normobaric hypoxia equivalent to an altitude of 4,000m. NBR and HBR interventions were conducted in a random order and separated by a washout period. Blood was drawn prior to (Pre), during, and post bed rest (R1, R2, R4) to analyze the individual variation in the responses of red blood cells (RBC), erythropoietin (EPO), and reticulocytes (Rct) to bed rest and hypoxia. No significant differences were found in the mean ∆(Pre-Post) values of EPO across projects (LunHab, FemHab, and PlanHab; p>0.05), however, female EPO responses to NBR (Range - 17.39, IQR – 12.97 mIU.ml−1) and HBR (Range – 49.00, IQR – 10.91 mIU.ml−1) were larger than males (LunHab NBR Range – 4.60, IQR – 2.03; HBR Range – 7.10, IQR – 2.78; PlanHab NBR Range – 7.23, IQR – 1.37; HBR Range – 9.72, IQR – 4.91 mIU.ml−1). Bed rest duration had no impact on the heterogeneity of EPO, Rct, and RBC responses (10-d v 21-d). The resultant hematological changes that occur during NBR and HBR are not proportional to the acute EPO response. The following cascade of hematological responses to NBR and HBR suggests that the source of variability in the present data is due to mechanisms related to hypoxia as opposed to inactivity alone. Studies investigating hematological changes should structure their study design to explore these mechanistic responses and elucidate the discord between the EPO response and hematological cascade to fully assess heterogeneity.
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Affiliation(s)
- Joshua T. Royal
- Environmental Physiology and Ergonomics Lab, Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Ola Eiken
- Division of Environmental Physiology, Swedish Aerospace Physiology Center, KTH Royal Institute of Technology, Solna, Sweden
| | - Michail E. Keramidas
- Division of Environmental Physiology, Swedish Aerospace Physiology Center, KTH Royal Institute of Technology, Solna, Sweden
| | - Adam C. McDonnell
- Environmental Physiology and Ergonomics Lab, Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Igor B. Mekjavic
- Environmental Physiology and Ergonomics Lab, Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
- *Correspondence: Igor B. Mekjavic,
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Salvadego D, Grassi B, Keramidas ME, Eiken O, McDonnell AC, Mekjavic IB. Heterogeneity of human adaptations to bed rest and hypoxia: a retrospective analysis within the skeletal muscle oxidative function. Am J Physiol Regul Integr Comp Physiol 2021; 321:R813-R822. [PMID: 34585615 DOI: 10.1152/ajpregu.00053.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This retrospective study was designed to analyze the interindividual variability in the responses of different variables characterizing the skeletal muscle oxidative function to normoxic (N-BR) and hypoxic (H-BR) bed rests and to a hypoxic ambulatory confinement (H-AMB) of 10 and 21 days. We also assessed whether and how the addition of hypoxia to bed rest might influence the heterogeneity of the responses. In vivo measurements of O2 uptake and muscle fractional O2 extraction were carried out during an incremental one-leg knee-extension exercise. Mitochondrial respiration was assessed in permeabilized muscle fibers. A total of 17 subjects were included in this analysis. This analysis revealed a similar variability among subjects in the alterations induced by N-BR and H-BR both in peak O2 uptake (SD: 4.1% and 3.3% after 10 days; 4.5% and 8.1% after 21 days, respectively) and peak muscle fractional O2 extraction (SD: 5.9% and 7.3% after 10 days; 6.5% and 7.3% after 21 days), independently from the duration of the exposure. The individual changes measured in these variables were significantly related (r = 0.66, P = 0.004 after N-BR; r = 0.61, P = 0.009 after H-BR). Mitochondrial respiration showed a large variability of response after both N-BR (SD: 25.0% and 15.7% after 10 and 21 days) and H-BR (SD: 13.0% and 19.8% after 10 and 21 days); no correlation was found between N-BR and H-BR changes. When added to bed rest, hypoxia altered the individual adaptations within the mitochondria but not those intrinsic to the muscle oxidative function in vivo, both after the short- and medium-term exposures.
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Affiliation(s)
- Desy Salvadego
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Bruno Grassi
- 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
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Adam C McDonnell
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - 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
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McDonnell AC, Eiken O, Mekjavic IB, Žlak N, Drobnič M. The influence of a sustained 10-day hypoxic bed rest on cartilage biomarkers and subchondral bone in females: The FemHab study. Physiol Rep 2021; 8:e14413. [PMID: 32333524 PMCID: PMC7182690 DOI: 10.14814/phy2.14413] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/11/2020] [Accepted: 03/16/2020] [Indexed: 12/19/2022] Open
Abstract
This study assessed the influence of a 10‐day hypoxic bed rest on cartilage biomarkers and subchondral bone density across the patellofemoral joint (PFJ). Within clinical settings hypoxic tissue may arise in several types of disorders. Furthermore, a hypoxic environment is being considered for space flight habitats in the near future. Female participants (N = 12) participated in this study comprising three 10‐day interventions: hypoxic ambulation (HAMB), normoxic bed rest (NBR), and hypoxic bed rest (HBR). Venous samples were collected prior to (day −2: Pre) and during the intervention (days 2 and 5), immediately before reambulation (D11) and 24 hr post intervention (R1). Blood samples were analyzed for: aggrecan, hyaluronan, Type IIA procollagen amino terminal propeptide (PIIANP), and cartilage oligomeric matrix protein (COMP). Total bone mineral density (BMD) in eight regions (2 mm × 10 mm) across the PFJ was determined. The three interventions (HAMB, HBR, and NBR) did not induce any significant changes in the cartilage biomarkers of hyaluronan or PIIANP. Aggrecan increased during the HAMB trial to 2.02 fold the Pre value. COMP decreased significantly in both NBR & HBR compared to HAMB on D5. There were significant differences in BMD measured across the PFJ from cortical patellar bone (735 to 800 mg/cm3) to femur trabecular (195 to 226 mg/cm3). However, there were no significant changes in BMD from Pre to Post bed rest. These results indicate that there were no significant detectable effects of inactivity/unloading on subchondral bone density. The biomarker of cartilage, COMP, decreased on D5, whereas the addition of hypoxia to bed rest had no effect, it appears that hypoxia in combination with ambulation counteracted this decrease.
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Affiliation(s)
- Adam C McDonnell
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Solna, Sweden
| | - Igor B Mekjavic
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Solna, Sweden.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Nik Žlak
- Department of Orthopaedic Surgery, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Matej Drobnič
- Department of Orthopaedic Surgery, University Medical Centre Ljubljana, Ljubljana, Slovenia
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No ergogenic effects of a 10-day combined heat and hypoxic acclimation on aerobic performance in normoxic thermoneutral or hot conditions. Eur J Appl Physiol 2019; 119:2513-2527. [PMID: 31555926 DOI: 10.1007/s00421-019-04215-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 08/21/2019] [Indexed: 10/25/2022]
Abstract
PURPOSE Hypoxic acclimation enhances convective oxygen delivery to the muscles. Heat acclimation-elicited thermoregulatory benefits have been suggested not to be negated by adding daily exposure to hypoxia. Whether concomitant acclimation to both heat and hypoxia offers a synergistic enhancement of aerobic performance in thermoneutral or hot conditions remains unresolved. METHODS Eight young males ([Formula: see text]: 51.6 ± 4.6 mL min-1 kg-1) underwent a 10-day normobaric hypoxic confinement (FiO2 = 0.14) interspersed with daily 90-min normoxic controlled hyperthermia (target rectal temperature: 38.5 °C) exercise sessions. Prior to, and following the confinement, the participants conducted a 30-min steady-state exercise followed by incremental exercise to exhaustion on a cycle ergometer in thermoneutral normoxic (NOR), thermoneutral hypoxic (FiO2 = 0.14; HYP) and hot (35 °C, 50% relative humidity; HE) conditions in a randomized and counterbalanced order. The steady-state exercise was performed at 40% NOR peak power output (Wpeak) to evaluate thermoregulatory function. Blood samples were obtained from an antecubital vein before, on days 1 and 10, and the first day post-acclimation. RESULTS [Formula: see text] and ventilatory thresholds were not modified in any environment following acclimation. Wpeak increased by 6.3 ± 3.4% in NOR and 4.0 ± 4.9% in HE, respectively. The magnitude and gain of the forehead sweating response were augmented in HE post-acclimation. EPO increased from baseline (17.8 ± 7.0 mIU mL-1) by 10.7 ± 8.8 mIU mL-1 on day 1 but returned to baseline levels by day 10 (15.7 ± 5.9 mIU mL-1). DISCUSSION A 10-day combined heat and hypoxic acclimation conferred only minor benefits in aerobic performance and thermoregulation in thermoneutral or hot conditions. Thus, adoption of such a protocol does not seem warranted.
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Durand M, Collombet JM, Frasca S, Sarilar V, Lataillade JJ, Le Bousse-Kerdilès MC, Holy X. Separate and combined effects of hypobaric hypoxia and hindlimb suspension on skeletal homeostasis and hematopoiesis in mice. HYPOXIA 2019; 7:41-52. [PMID: 31440522 PMCID: PMC6667353 DOI: 10.2147/hp.s195827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/15/2019] [Indexed: 12/14/2022]
Abstract
Purpose Bone marrow response to an organismal stress is made by orchestrating the interplay between hematopoietic stem/progenitor cells (HSPCs) and mesenchymal stromal cells (MSCs). Neither the cellular nor the molecular factors that regulate this process are fully understood, especially since this mechanism probably varies depending on the type of stress. Herein, we explored the differentiation and fate of MSCs and HSPCs in mice challenged with a hematopoietic stress or a mechanical stress applied separately or in combination. Methods Mice were subjected to 4 days of hypobaric hypoxia (hematopoietic challenge) and/or 7 days of hindlimb suspension (stromal challenge) and then sacrificed for blood and bone collection. Using hematological measurements, colony-forming unit assays, bone histomorphometry and array-based multiplex ELISA analysis, we evaluated challenge influences on both MSC and HSPC mobilization, differentiation (osteoblasts, osteoclasts, and mature blood cells) and fate. Results We found that hypoxia leads to HSPC mobilization and that an imbalance between bone formation and bone resorption accounts for this mobilization. Whilst suspension is also associated with an imbalance between bone formation and bone resorption, it does not induce HSPC mobilization. Then, we revealed cellular interactions by combining hematopoietic and stromal challenges together in mice. We showed that the hypoxia-driven HSPC mobilization is moderated by suspension. Moreover, when applied in a hypoxic environment, suspension offsets bone imbalance. We identified stroma cell-derived factors MIP-1α, HGF and SDF-1 as potent molecular key players sustaining interactions between hindlimb suspension and hypobaric hypoxia. Conclusion Taken together, our data highlight the benefit of combining different types of stress to better understand the interplay between MSCs and HSPCs.
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Affiliation(s)
- Marjorie Durand
- Department of Medical and Surgical Assistance to the Armed Forces, French Forces Biomedical Research Institute (IRBA), Brétigny sur Orge, Cedex 91223, France
| | - Jean-Marc Collombet
- Department of Medical and Surgical Assistance to the Armed Forces, French Forces Biomedical Research Institute (IRBA), Brétigny sur Orge, Cedex 91223, France
| | - Sophie Frasca
- Department of Medical and Surgical Assistance to the Armed Forces, French Forces Biomedical Research Institute (IRBA), Brétigny sur Orge, Cedex 91223, France
| | - Véronique Sarilar
- Department of Platforms & Technological Research, French Armed Forces Biomedical Research Institute (IRBA), Brétigny sur Orge, Cedex, 91223, France
| | - Jean-Jacques Lataillade
- Department of Medical and Surgical Assistance to the Armed Forces, French Forces Biomedical Research Institute (IRBA), Brétigny sur Orge, Cedex 91223, France.,Unit for Research Development, Armed Forces Blood Transfusion Center, Clamart, Cedex 92141, France
| | | | - Xavier Holy
- Department of Platforms & Technological Research, French Armed Forces Biomedical Research Institute (IRBA), Brétigny sur Orge, Cedex, 91223, France
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Sotiridis A, Debevec T, McDonnell AC, Ciuha U, Eiken O, Mekjavic IB. Exercise cardiorespiratory and thermoregulatory responses in normoxic, hypoxic, and hot environment following 10-day continuous hypoxic exposure. J Appl Physiol (1985) 2018; 125:1284-1295. [DOI: 10.1152/japplphysiol.01114.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We examined the effects of acclimatization to normobaric hypoxia on aerobic performance and exercise thermoregulatory responses under normoxic, hypoxic, and hot conditions. Twelve men performed tests of maximal oxygen uptake (V̇O2max) in normoxic (NOR), hypoxic [HYP; 13.5% fraction of inspired oxygen (FiO2)], and hot (HE; 35°C, 50% relative humidity) conditions in a randomized manner before and after a 10-day continuous normobaric hypoxic exposure [FiO2 = 13.65 (0.35)%, inspired partial pressure of oxygen = 87 (3) mmHg]. The acclimatization protocol included daily exercise [60 min at 50% hypoxia-specific peak power output (Wpeak)]. All maximal tests were preceded by a steady-state exercise (30 min at 40% Wpeak) to assess the sweating response. Hematological data were assessed from venous blood samples obtained before and after acclimatization. V̇o2max increased by 10.7% ( P = 0.002) and 7.9% ( P = 0.03) from pre-acclimatization to post acclimatization in NOR and HE, respectively, whereas no differences were found in HYP [pre: 39.9 (3.8) vs. post: 39.4 (5.1) ml·kg−1·min−1, P = 1.0]. However, the increase in V̇O2max did not translate into increased Wpeak in either NOR or HE. Maximal heart rate and ventilation remained unchanged following acclimatization. Νo differences were noted in the sweating gain and thresholds independent of the acclimatization or environmental conditions. Hypoxic acclimatization markedly increased hemoglobin ( P < 0.001), hematocrit ( P < 0.001), and extracellular HSP72 ( P = 0.01). These data suggest that 10 days of normobaric hypoxic acclimatization combined with moderate-intensity exercise training improves V̇o2max in NOR and HE, but does not seem to affect exercise performance or thermoregulatory responses in any of the tested environmental conditions. NEW & NOTEWORTHY The potential crossover effect of hypoxic acclimatization on performance in the heat remains unexplored. Here we show that 10-day continuous hypoxic acclimatization combined with moderate-intensity exercise training can increase maximal oxygen uptake in hot conditions.
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Affiliation(s)
- Alexandros Sotiridis
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
- Jozef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Tadej Debevec
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
| | - Adam C. McDonnell
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Urša Ciuha
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Ola Eiken
- Department of Environmental Physiology, School of Chemistry, Biotechnology and Health, Royal Institute of Technology, Solna, Sweden
| | - Igor B. Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
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Debevec T, Ganse B, Mittag U, Eiken O, Mekjavic IB, Rittweger J. Hypoxia Aggravates Inactivity-Related Muscle Wasting. Front Physiol 2018; 9:494. [PMID: 29867545 PMCID: PMC5962751 DOI: 10.3389/fphys.2018.00494] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 04/18/2018] [Indexed: 11/13/2022] Open
Abstract
Poor musculoskeletal state is commonly observed in numerous clinical populations such as chronic obstructive pulmonary disease (COPD) and heart failure patients. It, however, remains unresolved whether systemic hypoxemia, typically associated with such clinical conditions, directly contributes to muscle deterioration. We aimed to experimentally elucidate the effects of systemic environmental hypoxia upon inactivity-related muscle wasting. For this purpose, fourteen healthy, male participants underwent three 21-day long interventions in a randomized, cross-over designed manner: (i) bed rest in normoxia (NBR; PiO2 = 133.1 ± 0.3 mmHg), (ii) bed rest in normobaric hypoxia (HBR; PiO2 = 90.0 ± 0.4 mmHg) and ambulatory confinement in normobaric hypoxia (HAmb; PiO2 = 90.0 ± 0.4 mmHg). Peripheral quantitative computed tomography and vastus lateralis muscle biopsies were performed before and after the interventions to obtain thigh and calf muscle cross-sectional areas and muscle fiber phenotype changes, respectively. A significant reduction of thigh muscle size following NBR (-6.9%, SE 0.8%; P < 0.001) was further aggravated following HBR (-9.7%, SE 1.2%; P = 0.027). Bed rest-induced muscle wasting in the calf was, by contrast, not exacerbated by hypoxic conditions (P = 0.47). Reductions in both thigh (-2.7%, SE 1.1%, P = 0.017) and calf (-3.3%, SE 0.7%, P < 0.001) muscle size were noted following HAmb. A significant and comparable increase in type 2× fiber percentage of the vastus lateralis muscle was noted following both bed rest interventions (NBR = +3.1%, SE 2.6%, HBR = +3.9%, SE 2.7%, P < 0.05). Collectively, these data indicate that hypoxia can exacerbate inactivity-related muscle wasting in healthy active participants and moreover suggest that the combination of both, hypoxemia and lack of activity, as seen in COPD patients, might be particularly harmful for muscle tissue.
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Affiliation(s)
- Tadej Debevec
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.,Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Bergita Ganse
- Department of Orthopaedic Trauma, RWTH Aachen University Hospital, Aachen, Germany.,Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Uwe Mittag
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, KTH 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, BC, Canada
| | - Jörn Rittweger
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Department of Pediatrics and Adolescent Medicine, University of Cologne, Cologne, Germany
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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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Strewe C, Zeller R, Feuerecker M, Hoerl M, Matzel S, Kumprej I, Crispin A, Johannes B, Debevec T, Mekjavic IB, Eiken O, Thiel M, Schelling G, Choukèr A. PlanHab Study: Consequences of combined normobaric hypoxia and bed rest on adenosine kinetics. Sci Rep 2018; 8:1762. [PMID: 29379127 PMCID: PMC5788919 DOI: 10.1038/s41598-018-20045-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/20/2017] [Indexed: 12/24/2022] Open
Abstract
Adenosine plays a role in the energy supply of cells and provokes differential, hormone-like functions in circulating cells and various tissues. Its release is importantly regulated by oxygen tension. This renders adenosine and its kinetics interesting to investigate in humans subjected to low oxygen conditions. Especially for space exploration scenarios, hypoxic conditions - together with reduced gravity - represent two foreseen living conditions when planning manned long-duration space missions or planetary habitats. The PlanHab study investigated microgravity through inactivity in bed rest and normobaric hypoxia to examine their independent or combined effect on adenosine and its kinetics. Healthy male subjects (n = 14) completed three 21-day interventions: hypoxic bed rest (HBR); hypoxic ambulatory confinement (HAMB); normoxic bed rest (NBR). The interventions were separated by 4 months. Our hypothesis of a hypoxia-triggered increase in adenosine was confirmed in HAMB but unexpectedly also in NBR. However, the highest adenosine levels were noted following HBR. Furthermore, the percentage of hemolysis was elevated in HBR whereas endothelial integrity markers stayed low in all three interventions. In summary, these data suggest that neocytolysis accounts for these effects while we could reduce evidence for microcirculatory changes.
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Affiliation(s)
- C Strewe
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany
| | - R Zeller
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany
| | - M Feuerecker
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany
| | - M Hoerl
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany
| | - S Matzel
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany
| | - I Kumprej
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany.,Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - A Crispin
- Institute for Medical Information Processing, Biometry and Epidemiology, Klinikum Großhadern, University of Munich, Munich, Germany
| | - B Johannes
- Division of Space Physiology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - T Debevec
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.,Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
| | - I B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - O Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden
| | - M Thiel
- Department of Anaesthesiology and Surgical Intensive Care Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - G Schelling
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany
| | - A Choukèr
- Department of Anaesthesiology, University Hospital, LMU Munich, Laboratory of Translational Research "Stress and Immunity", Munich, Germany.
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10
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Morrison SA, Mirnik D, Korsic S, Eiken O, Mekjavic IB, Dolenc-Groselj L. Bed Rest and Hypoxic Exposure Affect Sleep Architecture and Breathing Stability. Front Physiol 2017; 8:410. [PMID: 28676764 PMCID: PMC5476730 DOI: 10.3389/fphys.2017.00410] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 05/30/2017] [Indexed: 11/13/2022] Open
Abstract
Objective: Despite over 50 years of research on the physiological effects of sustained bed rest, data characterizing its effects on sleep macrostructure and breathing stability in humans are scarce. This study was conducted to determine the effects of continuous exposure to hypoxia and sustained best rest, both individually and combined, on nocturnal sleep and breathing stability. Methods: Eleven participants completed three randomized, counter-balanced, 21-days trials of: (1) normoxic bed rest (NBR, PIO2 = 133.1 ± 0.3), (2) hypoxic ambulatory confinement (HAMB, PIO2 = 90.0 ± 0.4) and (3) hypoxic bed rest (HBR, PIO2 = 90.0 ± 0.4; ~4,000 m equivalent altitude). Full objective polysomnography was performed at baseline, on Night 1 and Night 21 in each condition. Results: In NBR Night 1, more time was spent in light sleep (10 ± 2%) compared to baseline (8 ± 2%; p = 0.028); Slow-wave sleep (SWS) was reduced from baseline in the hypoxic-only trial by 18% (HAMB Night 21, p = 0.028) and further reduced by 33% (HBR Night 1, p = 0.010), and 36% (HBR Night 21, p = 0.008) when combined with bed rest. The apnea-hypopnea index doubled from Night 1 to Night 21 in HBR (32–62 events·h−1) and HAMB (31–59 events·h−1; p = 0.002). Those who experienced greatest breathing instability from Night 1 to Night 21 (NBR) were correlated to unchanged or higher (+1%) night SpO2 concentrations (R2 = 0.471, p = 0.020). Conclusion: Bed rest negatively affects sleep macrostructure, increases the apnea-hypopnea index, and worsens breathing stability, each independently exacerbated by continuous exposure to hypoxia.
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Affiliation(s)
- Shawnda A Morrison
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan InstituteLjubljana, Slovenia.,Faculty of Health Sciences, University of PrimorskaIzola, Slovenia.,Division of Neurology, Institute of Clinical Neurophysiology, University Medical CentreLjubljana, Slovenia
| | - Dani Mirnik
- Division of Neurology, Institute of Clinical Neurophysiology, University Medical CentreLjubljana, Slovenia
| | - Spela Korsic
- Division of Neurology, Institute of Clinical Neurophysiology, University Medical CentreLjubljana, Slovenia
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of TechnologyStockholm, Sweden
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan InstituteLjubljana, Slovenia.,Department of Biomedical Physiology and Kinesiology, Simon Fraser UniversityBurnaby, BC, Canada
| | - Leja Dolenc-Groselj
- Division of Neurology, Institute of Clinical Neurophysiology, University Medical CentreLjubljana, Slovenia
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11
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Keramidas ME, Mekjavic IB, Eiken O. LunHab: interactive effects of a 10 day sustained exposure to hypoxia and bedrest on aerobic exercise capacity in male lowlanders. Exp Physiol 2017; 102:694-710. [DOI: 10.1113/ep086167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 03/20/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Michail E. Keramidas
- 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
- Department of Biomedical Physiology and Kinesiology; Simon Fraser University; Burnaby BC 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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12
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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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13
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Keramidas ME, Mekjavic IB, Kölegård R, Choukèr A, Strewe C, Eiken O. PlanHab: Hypoxia counteracts the erythropoietin suppression, but seems to exaggerate the plasma volume reduction induced by 3 weeks of bed rest. Physiol Rep 2016; 4:4/7/e12760. [PMID: 27081163 PMCID: PMC4831328 DOI: 10.14814/phy2.12760] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 03/16/2016] [Indexed: 11/24/2022] Open
Abstract
The study examined the distinct and synergistic effects of hypoxia and bed rest on the erythropoietin (EPO) concentration and relative changes in plasma volume (PV). Eleven healthy male lowlanders underwent three 21‐day confinement periods, in a counterbalanced order: (1) normoxic bed rest (NBR; PIO2: 133.1 ± 0.3 mmHg); (2) hypoxic bed rest (HBR; PIO2: 90.0 ± 0.4 mmHg, ambient simulated altitude of ~4000 m); and (3) hypoxic ambulation (HAMB; PIO2: 90.0 ± 0.4 mmHg). Blood samples were collected before, during (days 2, 5, 14, and 21) and 2 days after each confinement to determine EPO concentration. Qualitative differences in PV changes were also estimated by changes in hematocrit and hemoglobin concentration along with concomitant changes in plasma renin concentration. NBR caused an initial reduction in EPO by ~39% (P = 0.04). By contrast, HBR enhanced EPO (P = 0.001), but the increase was less than that induced by HAMB (P < 0.01). All three confinements caused a significant reduction in PV (P < 0.05), with a substantially greater drop in HBR than in the other conditions (P < 0.001). Thus, present results suggest that hypoxia prevents the EPO suppression, whereas it seems to exaggerate the PV reduction induced by bed rest.
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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
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Roger Kölegård
- Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden
| | - Alexander Choukèr
- Department of Anaesthesiology, Stress and Immunology Lab, University of Munich, Munich, Germany
| | - Claudia Strewe
- Department of Anaesthesiology, Stress and Immunology Lab, University of Munich, Munich, Germany
| | - 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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