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Kumar P, Bharti VK, Kumar K. Effect of short-term exposure to high-altitude hypoxic climate on feed-intake, blood glucose level and physiological responses of native and non-native goat. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2024; 68:795-806. [PMID: 38374293 DOI: 10.1007/s00484-024-02624-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 01/03/2024] [Accepted: 01/14/2024] [Indexed: 02/21/2024]
Abstract
The exposure to high altitude and cold stress poses challenges in maintaining normal physiological standards and body homeostasis in non-native animals. To enhance our understanding of the physiology of native and non-native goats in high-altitude environments, we conducted a comparative study to examine the impact of natural hypoxic and cold stress conditions on their feed intake (FIT) and associated changes in physiological responses, including plasma glucose concentration (PGC). The study took place at an altitude of 3505.2 m above mean sea level and involved twenty-two healthy females from two different breeds of goats. This study was conducted over a period of 56 days after the arrival of non-native Black Bengal goats (BBN) and compared with native Changthangi (CHAN) goats. Both groups were extensively reared in a natural high-altitude and cold-stress environment in Leh, India, and were subjected to defined housing and management practices. The parameters evaluated included FIT, PGC, respiration rate, heart rate, pulse rate, and rectal temperature. High altitudes had a significant (p < 0.05) impact on FIT, PGC, respiration rate, heart rate, pulse rate, and rectal temperature in BBN, whereas these parameters remained stable in CHAN throughout the study period. Additionally, the detrimental effects of high-altitude stress were more pronounced in non-native goats compared to native goats. These findings suggest that physiological responses in non-native goats tend to stabilize after an initial period of adverse effects in high-altitude environments. Based on the physiological responses and glucose concentration, it is recommended to pay special attention to the nutrition of non-native goats for up to the third week (21 days) after their arrival in high-altitude areas.
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Affiliation(s)
- Prabhat Kumar
- DRDO-Defence Institute of High-Altitude Research (DIHAR), Leh, Ladakh UT, India.
- Indira Gandhi Institute of Medical Sciences (IGIMS), Patna, Bihar, India.
| | - Vijay K Bharti
- DRDO-Defence Institute of High-Altitude Research (DIHAR), Leh, Ladakh UT, India.
| | - Krishna Kumar
- DRDO-Defence Institute of High-Altitude Research (DIHAR), Leh, Ladakh UT, India
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Abstract
This book chapter is drafted for biologists with experimental experiences in ROS biology but being newcomers in the field of modeling. We start with a general introduction about computational modeling in biology and an overview of software tools suitable for beginners. This chapter encompasses an introduction to computational models with special focus on simulation of ROS dynamics. A step-by-step tutorial follows providing guidance for all relevant model development processes. This course of action gives a comprehensible way to understand the benefits of computational models and to gain the necessary knowledge to build own small equation-based models. Small models can be created without any special programming expertise or in-depth technical and mathematical knowledge. Afterward in the final section, a short overview of pitfalls, challenges, and limitations is provided, combined with suggestions for further reading to improve and expand modeling skills of biologists.
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Affiliation(s)
- Jana Schleicher
- Experimental Transplantation Surgery, Department of General, Visceral and Vascular Surgery, University Hospital Jena, Jena, Germany.
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3
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Digital Health for Enhanced Understanding and Management of Chronic Conditions: COPD as a Use Case. SYSTEMS MEDICINE 2021. [DOI: 10.1016/b978-0-12-801238-3.11690-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Kumar P, Bharti VK, Mukesh M. Chemometric Analysis of Antioxidant and Mineral Elements in Colostrum of Native and Non-native Goat Breeds to Hypoxic Conditions at High Altitude. Biol Trace Elem Res 2020; 196:446-453. [PMID: 31667684 DOI: 10.1007/s12011-019-01940-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 10/16/2019] [Indexed: 02/07/2023]
Abstract
Colostrum of goat is a well-known nutritional source of animal product, which is attributed to innumerable nutritional properties. To enrich nutritional resources for understanding various nutritional values of animal product at high altitude, chemometric analysis of antioxidant and mineral element study was carried out by comparing antioxidants capacity, free radical scavenging activity, and certain mineral elements in colostrums of native and non-native goat breeds. Colostrum samples were collected from native Changthangi (CNG) and non-native Sirohi (SIRO) goat breeds, situated at naturally exposed high altitude of 3505.2 m above mean sea level. The antioxidant of samples was measured by ferric reducing ability of plasma (FRAP) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) activity assay, and mineral elemental quantification of Fe, Mg, Mn, Zn, Co, Cu, K, Ca, B, Ni, and Cr was performed using ICP-OES. The values of FRAP, DPPH, and Fe, Mg, Mn, Zn, Co, Cu, K, and Ca in colostrums of native goat breed was significantly (p ≤ 0.05) higher than the non-native goat. These data conclude that high altitude native goat has more antioxidant and mineral elements in colostrum than non-native colostrum. This study could provide a basis for establishing the role of colostrum supplements as a natural source to strengthen the endurance to modalities for the survival of newborn kids of goat within the native high altitude environment. This is the first report of a comparative chemometric analysis of colostrums of goat species and can be utilized to characterize the nutritional aspect of animal product with unique antioxidant and mineral nutrients composition in colostrum of goat.
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Affiliation(s)
- Prabhat Kumar
- DRDO- Defence Institute of High Altitude Research (DIHAR), Leh, Ladakh, India.
| | - Vijay K Bharti
- DRDO- Defence Institute of High Altitude Research (DIHAR), Leh, Ladakh, India.
| | - M Mukesh
- ICAR - National Bureau of Animal Genetic Resources (NBAGR), Karnal, Haryana, India
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Vukic MD, Vukovic NL, Obradovic A, Matic M, Djukic M, Avdovic E. Redox status, DNA and HSA binding study of naturally occurring naphthoquinone derivatives. EXCLI JOURNAL 2020; 19:48-70. [PMID: 32038116 PMCID: PMC7003638 DOI: 10.17179/excli2019-1859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/19/2019] [Indexed: 12/16/2022]
Abstract
In the present work we modified the procedure for isolation of naphthoquinones α-methylbutyrylshikon (1), acetylshikonin (2) and β-hydroxyisovalerylshikonin (3) from Onosma visianii Clem. We also investigated possible mechanisms of 1, 2 and 3 as antitumor agents. Accordingly, we estimated concentrations of superoxide anion radical (O2.-), nitrite (NO2 -) and glutathione in HCT-116 and MDA-MB-231 cell lines. Compounds 1 and 3 expressed significant prooxidative activity, while all tested compounds exhibited significant increase in nitrite levels. Also, all examined compounds significantly increased the concentration of oxidized glutathione (GSSG), suggesting significant prooxidative disbalance. The levels of reduced glutathione (GSH) were also elevated as a part of antioxidative cell response. The data indicate that induced oxidative imbalance could be one of the triggers for previously recorded decreased viability of HCT-116 and MDA-MB-231 cells exposed to tested naphthoquinone derivatives. Moreover, we examined interactions mode of compounds 1, 2 and 3 with CT-DNA as one of the crucial targets of many molecules that express cytotoxic activity. The results obtained by UV-visible, fluorescence and molecular docking study revealed that 1, 2 and 3 bound to CT-DNA through minor groove binding. Furthermore, the interactions between HSA and 1, 2 and 3 were examined employing the same methods as for the CT-DNA interaction study. Based on the obtained results, it can be concluded that naphthoquinones 1, 2 and 3 could be effectively transported by human serum albumin. As a conclusion, this study provides further insight of antitumor activity of selected naphthoquinones.
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Affiliation(s)
- Milena D Vukic
- Department of Chemistry, Faculty of Science, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia
| | - Nenad L Vukovic
- Department of Chemistry, Faculty of Science, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia
| | - Ana Obradovic
- Department of Biology and Ecology, Faculty of Science, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia
| | - Milos Matic
- Department of Biology and Ecology, Faculty of Science, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia
| | - Maja Djukic
- Department of Chemistry, Faculty of Science, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia
| | - Edina Avdovic
- Department of Chemistry, Faculty of Science, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia.,Department of Sciences, Institute for Information Technologies Kragujevac, University of Kragujevac, Jovana Cvijića bb, 34000 Kragujevac, Serbia
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Tényi Á, Vela E, Cano I, Cleries M, Monterde D, Gomez-Cabrero D, Roca J. Risk and temporal order of disease diagnosis of comorbidities in patients with COPD: a population health perspective. BMJ Open Respir Res 2018; 5:e000302. [PMID: 29955364 PMCID: PMC6018856 DOI: 10.1136/bmjresp-2018-000302] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/22/2018] [Indexed: 02/06/2023] Open
Abstract
Introduction Comorbidities in patients with chronic obstructive pulmonary disease (COPD) generate a major burden on healthcare. Identification of cost-effective strategies aiming at preventing and enhancing management of comorbid conditions in patients with COPD requires deeper knowledge on epidemiological patterns and on shared biological pathways explaining co-occurrence of diseases. Methods The study assesses the co-occurrence of several chronic conditions in patients with COPD using two different datasets: Catalan Healthcare Surveillance System (CHSS) (ES, 1.4 million registries) and Medicare (USA, 13 million registries). Temporal order of disease diagnosis was analysed in the CHSS dataset. Results The results demonstrate higher prevalence of most of the diseases, as comorbid conditions, in elderly (>65) patients with COPD compared with non-COPD subjects, an effect observed in both CHSS and Medicare datasets. Analysis of temporal order of disease diagnosis showed that comorbid conditions in elderly patients with COPD tend to appear after the diagnosis of the obstructive disease, rather than before it. Conclusion The results provide a population health perspective of the comorbidity challenge in patients with COPD, indicating the increased risk of developing comorbid conditions in these patients. The research reinforces the need for novel approaches in the prevention and management of comorbidities in patients with COPD to effectively reduce the overall burden of the disease on these patients.
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Affiliation(s)
- Ákos Tényi
- Hospital Clinic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.,Center for Biomedical Network Research in Respiratory Diseases (CIBERES), Madrid, Spain
| | - Emili Vela
- Unitat d'Informació i Coneixement, Servei Catala de la Salut de la Generalitat de Catalunya, Barcelona, Catalunya, Spain
| | - Isaac Cano
- Hospital Clinic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.,Center for Biomedical Network Research in Respiratory Diseases (CIBERES), Madrid, Spain
| | - Montserrat Cleries
- Unitat d'Informació i Coneixement, Servei Catala de la Salut de la Generalitat de Catalunya, Barcelona, Catalunya, Spain
| | - David Monterde
- Serveis Centrals, Institut Català de la Salut, Barcelona, Spain
| | - David Gomez-Cabrero
- Mucosal and Salivary Biology Division, King's College London Dental Institute, London, UK.,Unit of Computational Medicine, Center for Molecular Medicine, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital and Science for Life Laboratory, Stockholm, Sweden.,Translational Bioinformatics Unit, Navarrabiomed, Complejo Hospitalario de Navarra (CHN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain
| | - Josep Roca
- Hospital Clinic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.,Center for Biomedical Network Research in Respiratory Diseases (CIBERES), Madrid, Spain
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Lewis P, Sheehan D, Soares R, Coelho AV, O'Halloran KD. Redox Remodeling Is Pivotal in Murine Diaphragm Muscle Adaptation to Chronic Sustained Hypoxia. Am J Respir Cell Mol Biol 2017; 55:12-23. [PMID: 26681636 DOI: 10.1165/rcmb.2015-0272oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mechanisms underpinning chronic sustained hypoxia (CH)-induced structural and functional adaptations in respiratory muscles are unclear despite the clinical relevance to respiratory diseases. The objectives of the present study were to thoroughly assess the putative role of CH-induced redox remodeling in murine diaphragm muscle over time and the subsequent effects on metabolic enzyme activities, catabolic signaling and catabolic processes, and diaphragm muscle contractile function. C57Bl6/J mice were exposed to normoxia or normobaric CH (fraction of inspired oxygen = 0.1) for 1, 3, or 6 weeks. A second cohort was exposed to CH for 6 weeks with and without antioxidant supplementation (tempol or N-acetyl cysteine). After CH exposure, we performed two-dimensional redox proteomics with mass spectrometry, enzyme activity assays, and cell-signaling assays on diaphragm homogenates. We also assessed diaphragm isotonic contractile and endurance properties ex vivo. Global protein redox changes in the diaphragm after CH are indicative of oxidation. Remodeling of proteins key to contractile, metabolic, and homeostatic functions was observed. Several oxidative and glycolytic enzyme activities were decreased by CH. Redox-sensitive chymotrypsin-like proteasome activity of the diaphragm was increased. CH decreased phospho-forkhead box O3a (FOXO3a) and phospho-mammalian target of rapamycin content. Hypoxia-inducible factor-1α and phospho-p38 mitogen-activated protein kinase content was increased in CH diaphragm, and this was attenuated by antioxidant treatment. CH exposure decreased force- and power-generating capacity of the diaphragm, and this was prevented by antioxidant supplementation with N-acetyl cysteine but not tempol. Redox remodeling is pivotal for diaphragm adaptation to CH, affecting metabolic activity, atrophy signaling, and functional performance. Antioxidant supplementation may be useful as an adjunctive therapy in respiratory-related diseases characterized by hypoxic stress.
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Affiliation(s)
| | - David Sheehan
- 2 School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland; and
| | - Renata Soares
- 3 Instituto de Tecnologia Quimica e Biologica António Xavier, Universidade Novade Lisboa, Lisbon, Portugal
| | - Ana Varela Coelho
- 3 Instituto de Tecnologia Quimica e Biologica António Xavier, Universidade Novade Lisboa, Lisbon, Portugal
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Qu TT, Deng JX, Li RL, Cui ZJ, Wang XQ, Wang L, Deng JB. Stress injuries and autophagy in mouse hippocampus after chronic cold exposure. Neural Regen Res 2017; 12:440-446. [PMID: 28469659 PMCID: PMC5399722 DOI: 10.4103/1673-5374.202932] [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] [Indexed: 01/14/2023] Open
Abstract
Cold exposure is an external stress factor that causes skin frostbite as well as a variety of diseases. Estrogen might participate in neuroprotection after cold exposure, but its precise mechanism remains unclear. In this study, mice were exposed to 10°C for 7 days and 0-4°C for 30 days to induce a model of chronic cold exposure. Results showed that oxidative stress-related c-fos and cyclooxygenase 2 expressions, MAP1LC3-labeled autophagic cells, Iba1-labeled activated microglia, and interleukin-1β-positive pyramidal cells were increased in the hippocampal CA1 area. Chronic cold exposure markedly elevated the levels of estrogen in the blood and the estrogen receptor, G protein-coupled receptor 30. These results indicate that neuroimmunoreactivity is involved in chronic cold exposure-induced pathological alterations, including oxidative stress, neuronal autophagy, and neuroimmunoreactivity. Moreover, estrogen exerts a neuroprotective effect on cold exposure.
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Affiliation(s)
- Ting-Ting Qu
- Institute of Neurobiology, College of Life Science, Henan University, Kaifeng, Henan Province, China.,Nursing College, Henan Vocational College of Applied Technology, Zhengzhou, Henan Province, China
| | - Jie-Xin Deng
- Institute of Neurobiology, College of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Rui-Ling Li
- Institute of Neurobiology, College of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Zhan-Jun Cui
- Institute of Neurobiology, College of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Xiao-Qing Wang
- Institute of Neurobiology, College of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Lai Wang
- Institute of Neurobiology, College of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Jin-Bo Deng
- Institute of Neurobiology, College of Life Science, Henan University, Kaifeng, Henan Province, China
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Marín de Mas I, Fanchon E, Papp B, Kalko S, Roca J, Cascante M. Molecular mechanisms underlying COPD-muscle dysfunction unveiled through a systems medicine approach. Bioinformatics 2016; 33:95-103. [PMID: 27794560 DOI: 10.1093/bioinformatics/btw566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 08/26/2016] [Accepted: 08/29/2016] [Indexed: 01/04/2023] Open
Abstract
MOTIVATION Skeletal muscle dysfunction is a systemic effect in one-third of patients with chronic obstructive pulmonary disease (COPD), characterized by high reactive-oxygen-species (ROS) production and abnormal endurance training-induced adaptive changes. However, the role of ROS in COPD remains unclear, not least because of the lack of appropriate tools to study multifactorial diseases. RESULTS We describe a discrete model-driven method combining mechanistic and probabilistic approaches to decipher the role of ROS on the activity state of skeletal muscle regulatory network, assessed before and after an 8-week endurance training program in COPD patients and healthy subjects. In COPD, our computational analysis indicates abnormal training-induced regulatory responses leading to defective tissue remodeling and abnormal energy metabolism. Moreover, we identified tnf, insr, inha and myc as key regulators of abnormal training-induced adaptations in COPD. The tnf-insr pair was identified as a promising target for therapeutic interventions. Our work sheds new light on skeletal muscle dysfunction in COPD, opening new avenues for cost-effective therapies. It overcomes limitations of previous computational approaches showing high potential for the study of other multi-factorial diseases such as diabetes or cancer. CONTACT jroca@clinic.ub.es or martacascante@ub.eduSupplementary information: Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Igor Marín de Mas
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Institute of Biomedicine of University of Barcelona (IBUB) and IDIBAPS, Diagonal 645, Barcelona 08028, Spain.,Institut d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona 08028, Spain.,Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Eric Fanchon
- Université Grenoble Alpes-CNRS, TIMC-IMAG UMR 5525, Faculté de Médecine, Grenoble 38041, France
| | - Balázs Papp
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Susana Kalko
- Bioinformatics Core Facility, IDIBAPS-CEK, Hospital Clínic, University de Barcelona, Barcelona 08036, Spain
| | - Josep Roca
- Institut d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona 08028, Spain.,Department of Pulmonary Medicine, Hospital Clínic, IDIBAPS, CIBERES, Universitat de Barcelona, Barcelona 08036, Spain
| | - Marta Cascante
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Institute of Biomedicine of University of Barcelona (IBUB) and IDIBAPS, Diagonal 645, Barcelona 08028, Spain.,Institut d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona 08028, Spain
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Murray AJ. Energy metabolism and the high-altitude environment. Exp Physiol 2015; 101:23-7. [PMID: 26315373 DOI: 10.1113/ep085317] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 08/20/2015] [Indexed: 01/08/2023]
Abstract
At high altitude the barometric pressure falls, challenging oxygen delivery to the tissues. Thus, whilst hypoxia is not the only physiological stress encountered at high altitude, low arterial P(O2) is a sustained feature, even after allowing adequate time for acclimatization. Cardiac and skeletal muscle energy metabolism is altered in subjects at, or returning from, high altitude. In the heart, energetic reserve falls, as indicated by lower phosphocreatine-to-ATP ratios. The underlying mechanism is unknown, but in the hypoxic rat heart fatty acid oxidation and respiratory capacity are decreased, whilst pyruvate oxidation is also lower after sustained hypoxic exposure. In skeletal muscle, there is not a consensus. With prolonged exposure to extreme high altitude (>5500 m) a loss of muscle mitochondrial density is seen, but this was not observed in a simulated ascent of Everest in hypobaric chambers. At more moderate high altitude, decreased respiratory capacity may occur without changes in mitochondrial volume density, and fat oxidation may be downregulated, although this is not seen in all studies. The underlying mechanisms, including the possible role of hypoxia-signalling pathways, remain to be resolved, particularly in light of confounding factors in the high-altitude environment. In high-altitude-adapted Tibetan natives, however, there is evidence of natural selection centred around the hypoxia-inducible factor pathway, and metabolic features in this population (e.g. low cardiac phosphocreatine-to-ATP ratios, increased cardiac glucose uptake and lower muscle mitochondrial densities) share similarities with those in acclimatized lowlanders, supporting a possible role for the hypoxia-inducible factor pathway in the metabolic response of cardiac and skeletal muscle energy metabolism to high altitude.
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Affiliation(s)
- Andrew J Murray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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Murray AJ, Horscroft JA. Mitochondrial function at extreme high altitude. J Physiol 2015; 594:1137-49. [PMID: 26033622 DOI: 10.1113/jp270079] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/21/2015] [Indexed: 01/01/2023] Open
Abstract
At high altitude, barometric pressure falls and with it inspired P(O2), potentially compromising O2 delivery to the tissues. With sufficient acclimatisation, the erythropoietic response increases red cell mass such that arterial O2 content (C(aO2)) is restored; however arterial P(O2)(P(aO2)) remains low, and the diffusion of O2 from capillary to mitochondrion is impaired. Mitochondrial respiration and aerobic capacity are thus limited, whilst reactive oxygen species (ROS) production increases. Restoration of P(aO2) with supplementary O2 does not fully restore aerobic capacity in acclimatised individuals, possibly indicating a peripheral impairment. With prolonged exposure to extreme high altitude (>5500 m), muscle mitochondrial volume density falls, with a particular loss of the subsarcolemmal population. It is not clear whether this represents acclimatisation or deterioration, but it does appear to be regulated, with levels of the mitochondrial biogenesis factor PGC-1α falling, and shows similarities to adapted Tibetan highlanders. Qualitative changes in mitochondrial function also occur, and do so at more moderate high altitudes with shorter periods of exposure. Electron transport chain complexes are downregulated, possibly mitigating the increase in ROS production. Fatty acid oxidation capacity is decreased and there may be improvements in biochemical coupling at the mitochondrial inner membrane that enhance O2 efficiency. Creatine kinase expression falls, possibly impairing high-energy phosphate transfer from the mitochondria to myofibrils. In climbers returning from the summit of Everest, cardiac energetic reserve (phosphocreatine/ATP) falls, but skeletal muscle energetics are well preserved, possibly supporting the notion that mitochondrial remodelling is a core feature of acclimatisation to extreme high altitude.
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Affiliation(s)
- Andrew J Murray
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - James A Horscroft
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
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