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Di Giulio C, Zara S, Mazzatenta A, Verratti V, Porzionato A, Cataldi A, Pokorski M. Aging and the Carotid Body: A Scoping Review. Respir Physiol Neurobiol 2023; 313:104063. [PMID: 37076025 DOI: 10.1016/j.resp.2023.104063] [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: 03/09/2023] [Accepted: 04/16/2023] [Indexed: 04/21/2023]
Abstract
The carotid body (CB) is a neuroepithelial tissue consisting of O2-sensitive glomus cells that constantly scan the arterial blood for O2 and generate a discharge as an inverse function of O2 content. Aging is a cumulative result of decreased O2 supply paralleled by a decreased O2 tissue demand and oxidative damage to cells derived from aerobic metabolism. Here we studied how CB affects the aging process. This is a study of CB ultrastructural morphometry and immunohistochemical expression of proteins underlying CB responsiveness. The study was based on human CBs obtained from cadavers of people who died due to traumatic events in young and old age. The study was supplemented by investigations of CBs obtained from young and old rats subjected to chronic normoxic and hypoxic conditions. We found changes in the old normoxic CBs akin to the effects of chronic hypoxia such as enhanced extracellular matrix, reduced synaptic contacts between glomus cells, fewer glomus cells, secretory vesicles, and mitochondria. These changes were accompanied by enhanced expressions of hypoxia-inducible factor one-alpha (HIF-1α), vascular endothelial growth factor (VEGF), and nitric oxide synthase (NOS2). We conclude that hypoxia and aging share a common background consisting of deficient O2 tissue supply, mitochondrial dysfunction, and a limited ability to deal with increased cellular oxidative stress. Aging leads to adaptative reductions in CB responsiveness to hypoxia shifting the chemosensory setpoint upward. We submit that the attenuated CB sensitivity at old age may be tantamount to "physiological denervation" leading to a gradual loss of the chemosensing role in the prevention of tissue hypoxia by increasing lung ventilation.
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Affiliation(s)
| | | | | | - Vittore Verratti
- Department of Psychological Sciences, Health, and Territory, University of Chieti-Pescara, Chieti Italy
| | - Andrea Porzionato
- Section of Human Anatomy, Department of Neuroscience, University of Padova, Padova, Italy
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van Doorslaer de Ten Ryen S, Dalle S, Terrasi R, Koppo K, Muccioli GG, Deldicque L. Regulation of the endocannabinoid system by endurance and resistance exercise in hypoxia in human skeletal muscle. J Appl Physiol (1985) 2023; 134:569-580. [PMID: 36701485 DOI: 10.1152/japplphysiol.00645.2022] [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: 01/27/2023] Open
Abstract
Exercise modulates the circulating levels of the endocannabinoids ligands N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) and possibly the levels of their receptors and downstream signaling in skeletal muscle. The aim of the present study was to investigate the regulation of the endocannabinoid system by several exercise paradigms in human skeletal muscle. A second aim was to compare endocannabinoid regulation in healthy and prediabetic people in response to an acute endurance exercise. Blood and muscle samples were taken before and after resistance and endurance exercise in normoxia and hypoxia to measure plasma endocannabinoid levels as well as muscle protein expression of CB1, CB2, and downstream signaling. We found that: 1) an acute resistance exercise session decreased plasma 2-AG and N-palmitoylethanolamine (PEA) levels in normoxia; 2) 4 wk resistance training decreased plasma AEA, PEA, and N-oleoylethanolamine (OEA) levels in both normoxia and hypoxia; 3) an acute moderate-intensity endurance exercise increased plasma OEA levels in the healthy and prediabetic groups in normoxia and hypoxia, whereas plasma 2-AG levels increased in the healthy group and AEA in the prediabetic group only in normoxia. The expression of the cannabinoid receptors was only marginally regulated by acute exercise, hypoxia, and prediabetes and downstream signaling did not follow the changes detected in the endocannabinoid ligands. Altogether, our results suggest that resistance and endurance exercise regulate the levels of the endocannabinoid ligands and CB1 expression in opposite ways. The physiological impact of the changes observed in the endocannabinoid ligands in human skeletal muscle after exercise needs further investigation.NEW & NOTEWORTHY We are the first to analyze both endocannabinoids ligands and receptors in response to endurance and resistance exercise. In addition, no study before has compared both exercise paradigms regarding endocannabinoid tone, which is of interest as endocannabinoids regulate energy metabolism, and these are different between endurance and resistance exercise. Furthermore, we investigated whether the endocannabinoid tone was differently regulated in response to acute endurance exercise in prediabetic people. Linking exercise, endocannabinoids and (pre)diabetic people has never been done before.
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Affiliation(s)
| | - Sebastiaan Dalle
- Department of Movement Sciences, Exercise Physiology Research Group, KU Leuven, Leuven, Belgium
| | - Romano Terrasi
- Louvain Drug Research Institute, Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Université catholique de Louvain, Brussels, Belgium
| | - Katrien Koppo
- Department of Movement Sciences, Exercise Physiology Research Group, KU Leuven, Leuven, Belgium
| | - Giulio G Muccioli
- Louvain Drug Research Institute, Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Université catholique de Louvain, Brussels, Belgium
| | - Louise Deldicque
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve, Belgium
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Effects of Prolonged Exposure to Hypobaric Hypoxia on Oxidative Stress: Overwintering in Antarctic Concordia Station. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:4430032. [PMID: 35535360 PMCID: PMC9078816 DOI: 10.1155/2022/4430032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/25/2022] [Accepted: 04/09/2022] [Indexed: 12/14/2022]
Abstract
Concordia Station is the permanent, research station on the Antarctic Plateau at 3230 m. During the eleventh winter-over campaign (DC11-2015; February 2015 to November 2015) at Antarctic Concordia Station, 13 healthy team members were studied and blood samples were collected at six different time points: baseline measurements (T0), performed at sea level before the departure, and during the campaign at 3, 7, 20, 90, and 300 days after arrival at Concordia Station. Reducing the partial pressure of O2 as barometric pressure falls, hypobaric hypoxia (HH) triggers several physiological adaptations. Among the others, increased oxidative stress and enhanced generation of reactive oxygen/nitrogen species (ROS/RNS), resulting in severe oxidative damage, were observed, which can share potential physiopathological mechanisms associated with many diseases. This study characterized the extent and time-course changes after acute and chronic HH exposure, elucidating possible fundamental mechanisms of adaptation. ROS, oxidative stress biomarkers, nitric oxide, and proinflammatory cytokines significantly increased (range 24-135%) during acute and chronic hypoxia exposure (peak 20th day) with a decrease in antioxidant capacity (peak 90th day: -52%). Results suggest that the adaptive response of oxidative stress balance to HH requires a relatively long time, more than 300th days, as all the observed variables do not return to the preexposition level. These findings may also be relevant to patients in whom oxygen availability is limited through disease (i.e., chronic heart and lung and/or kidney disease) and/or during long-duration space missions.
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Slivka D, Dumke C, Hailes W, Ruby B. Impact of Hypoxic Exercise Recovery on Skeletal Muscle Glycogen and Gene Expression. High Alt Med Biol 2021; 22:300-307. [PMID: 34142871 DOI: 10.1089/ham.2021.0028] [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: 11/13/2022] Open
Abstract
Slivka, Dustin, Charles Dumke, Walter Hailes, and Brent Ruby. Impact of hypoxic exercise recovery on skeletal muscle glycogen and gene expression. High Alt Med Biol. 22:300-307, 2021. Background: The impact of altitude during recovery from exercise is largely unknown. The purpose of this study was to determine the acute gene response and muscle glycogen re-synthesis after exercise when exposed to simulated high altitude during recovery. Materials and Methods: Twelve male participants (age, 25 ± 2 years; height, 178 ± 7 cm; weight, 78.8 ± 7.8 kg; VO2peak, 4.25 ± 0.59 l/min; Wpeak 307 ± 44 W; and body fat, 13.1% ± 1.2%) completed two trials (random order), which consisted of cycling for 90 minutes in laboratory conditions and then recovering for 6 hours in laboratory conditions (975 m; normoxia) or at a high simulated altitude (5,000 m; hypoxia). Results: Skeletal muscle biopsies from the vastus lateralis were obtained before exercise, after exercise, and 6 hours after exercise for the measurement of metabolic gene expression and muscle glycogen. Muscle glycogen decreased with exercise (61% ± 13%, p < 0.05) and increased with recovery (78% ± 35%, p < 0.05) with no difference between trials (p > 0.05). Hypoxia-inducible factor (HIF)-1α, HIF-2α, optic atrophy gene 1 (OPA-1), mitofusin 2 (MFN-2), and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) gene expression were suppressed after altitude exposure (p < 0.05), while mitochondrial fission 1 protein (FIS-1), phosphofructokinase (PFK), Cytochrome c oxidase (COX), and hexokinase (HK) were unaffected by altitude exposure (p > 0.05). Conclusions: High-altitude exposure during recovery from exercise inhibits gene expression associated with mitochondrial development without affecting muscle glycogen re-synthesis.
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Affiliation(s)
- Dustin Slivka
- School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, Nebraska, USA
| | - Charles Dumke
- School of Integrative Physiology and Athletic Training, University of Montana, Missoula, Montana, USA
| | - Walter Hailes
- School of Integrative Physiology and Athletic Training, University of Montana, Missoula, Montana, USA
| | - Brent Ruby
- School of Integrative Physiology and Athletic Training, University of Montana, Missoula, Montana, USA
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van Doorslaer de Ten Ryen S, Francaux M, Deldicque L. Regulation of satellite cells by exercise in hypoxic conditions: a narrative review. Eur J Appl Physiol 2021; 121:1531-1542. [PMID: 33745023 DOI: 10.1007/s00421-021-04641-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/10/2021] [Indexed: 12/16/2022]
Abstract
PURPOSE To investigate in vivo the adaptations of satellite cell induced by exercise performed in acute or chronic hypoxic conditions and their contribution to muscle remodeling and hypertrophy. METHODS Search terms related to exercise, hypoxia and satellite cells were entered on Embase, PubMed and Scopus. Studies were selected for their relevance in terms of regulation of satellite cells by in vivo exercise and muscle contraction in hypoxic conditions. RESULTS Satellite cell activation and proliferation seem to be enabled after acute hypoxic exercise via regulations induced by myogenic regulatory factors. Several studies reported also a role of the inflammatory pathway nuclear factor-kappa B and angiogenic factors such as vascular endothelial growth factor, both known to upregulate myogenesis. By stimulating angiogenesis, repeated exercise performed in acute hypoxia might contribute to satellite cell activation. Contrary to such exercise conditions, chronic exposure to hypoxia downregulates myogenesis despite the maintenance of physical activity. This impaired myogenesis might be induced by excessive oxidative stress and proteolysis. CONCLUSION In vivo studies suggest that, in comparison to exercise or hypoxia alone, exercise performed in a hypoxic environment, may improve or impair muscle remodeling induced by contractile activity depending upon the duration of hypoxia. Satellite cells seem to be major actors in these dichotomous adaptations. Further research on the role of angiogenesis, types of contraction and autophagy is needed for a better understanding of their respective role in hypoxic exercise-induced modulations of satellite cell activity in human.
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Affiliation(s)
- Sophie van Doorslaer de Ten Ryen
- Institute of Neuroscience, Université Catholique de Louvain, Place Pierre de Coubertin, 1 L08.10.01, 1348, Louvain-la-Neuve, Belgium
| | - Marc Francaux
- Institute of Neuroscience, Université Catholique de Louvain, Place Pierre de Coubertin, 1 L08.10.01, 1348, Louvain-la-Neuve, Belgium
| | - Louise Deldicque
- Institute of Neuroscience, Université Catholique de Louvain, Place Pierre de Coubertin, 1 L08.10.01, 1348, Louvain-la-Neuve, Belgium.
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Comparative analysis of peripheral blood reveals transcriptomic adaptations to extreme environments on the Qinghai-Tibetan Plateau in the gray wolf (Canis lupus chanco). ORG DIVERS EVOL 2019. [DOI: 10.1007/s13127-019-00405-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Di Giulio C. Ageing of the carotid body. J Physiol 2018; 596:3021-3027. [PMID: 29319194 DOI: 10.1113/jp275300] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/05/2018] [Indexed: 02/03/2023] Open
Abstract
The ageing process is characterized by a decline in several physiological functions resulting in a reduced capability to maintain homeostasis. The lowered homeostatic capacity seems to involve the carotid body (CB), whose role is to modulate ventilation and tissue oxygen supply. It thus plays a prime role in all ageing processes. Ageing causes marked changes in CB morphology. In older animals, it is enlarged and shows a concomitant decrease in the percentage of chemoreceptor tissue, as well as a proliferation of type II cells. The carotid glomitis is present with aggregates of lymphocytes and fibrosis of the lobules. Type I cells are dehydrated, with a profound vacuolization, a shrinking nucleus, and lipofuscin accumulation. With increased age, human CB shows a reduction in the number and volume of mitochondria, fewer synaptic junctions between glomi, along with a reduction in CB content of neurotransmitters, leading to a sort of 'physiological denervation'. Ageing could be interpreted as a cumulative result of oxidative damage to cells, which derives from aerobic metabolism. Moreover, metabolic rate is tightly correlated with life duration; thus a loss in mitochondrial function is one of the prime factors affecting CB ageing processes. The age-related reduction in synaptic junctions might be a self-protective mechanism through which cells buffer themselves against an accumulation of reactive oxygen species. The correlation between hypoxia and the life duration of CB cells remains an open question until how and why cells sense oxygen is understood.
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Affiliation(s)
- Camillo Di Giulio
- Department of Neurosciences Imaging and Clinical Sciences, "G. d'Annunzio" University of Chieti-Pescara, Italy
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Agrawal A, Rathor R, Suryakumar G. Oxidative protein modification alters proteostasis under acute hypobaric hypoxia in skeletal muscles: a comprehensive in vivo study. Cell Stress Chaperones 2017; 22:429-443. [PMID: 28425050 PMCID: PMC5425375 DOI: 10.1007/s12192-017-0795-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 03/28/2017] [Accepted: 03/30/2017] [Indexed: 12/14/2022] Open
Abstract
While numerous maladies are associated with hypobaric hypoxia, muscle protein loss is an important under studied topic. Hence, the present study was designed to investigate the mechanism of muscle protein loss at HH. SD rats were divided into normoxic rats, while remaining rats were exposed to simulated hypoxia equivalent to 282-torr pressure (equal to an altitude of 7620 m, 8% oxygen), at 25 °C for 6, 12, and 24 h. Post-exposure rats were sacrificed and analysis was performed. Ergo, muscle loss-related changes were observed at 12 and 24 h post-HH exposure. An increased reactive oxygen species production and decreased thiol content was observed in HH-exposed rats. This disturbance caused substantial protein oxidative modification in the form of protein carbonyl content and advanced oxidation protein products. The analysis showed increase levels of bityrosine, oxidized tryptophan, lysine conjugate, lysine conjugate with MDA, protein hydroperoxide, and protein-MDA product. These changes were also in agreement with increase in lipid hydroperoxides and MDA content. HSP-70 and HSP-60 were upregulated significantly, and this finding is corroborated with increase in ER stress biomarker, GRP-78. Overloading of cells with misfolded proteins further activated degradative machinery. Consequently, pro-apoptotic signaling cascade, caspase-3, and C/EBP homologous protein were also activated in 24-h HH exposure. Release of tryptophan and tyrosine was also increased with 24-h HH exposure, indicated protein degradation. Elevation in resting intracellular calcium ion, [Ca2+]i, was also observed at 12- and 24-h HH exposure. The present study provides a detailed mechanistic representation of muscle protein loss during HH exposure.
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Affiliation(s)
- Akanksha Agrawal
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi -54, India
| | - Richa Rathor
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi -54, India.
| | - Geetha Suryakumar
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi -54, India
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Blaauw B, Schiaffino S, Reggiani C. Mechanisms modulating skeletal muscle phenotype. Compr Physiol 2014; 3:1645-87. [PMID: 24265241 DOI: 10.1002/cphy.c130009] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mammalian skeletal muscles are composed of a variety of highly specialized fibers whose selective recruitment allows muscles to fulfill their diverse functional tasks. In addition, skeletal muscle fibers can change their structural and functional properties to perform new tasks or respond to new conditions. The adaptive changes of muscle fibers can occur in response to variations in the pattern of neural stimulation, loading conditions, availability of substrates, and hormonal signals. The new conditions can be detected by multiple sensors, from membrane receptors for hormones and cytokines, to metabolic sensors, which detect high-energy phosphate concentration, oxygen and oxygen free radicals, to calcium binding proteins, which sense variations in intracellular calcium induced by nerve activity, to load sensors located in the sarcomeric and sarcolemmal cytoskeleton. These sensors trigger cascades of signaling pathways which may ultimately lead to changes in fiber size and fiber type. Changes in fiber size reflect an imbalance in protein turnover with either protein accumulation, leading to muscle hypertrophy, or protein loss, with consequent muscle atrophy. Changes in fiber type reflect a reprogramming of gene transcription leading to a remodeling of fiber contractile properties (slow-fast transitions) or metabolic profile (glycolytic-oxidative transitions). While myonuclei are in postmitotic state, satellite cells represent a reserve of new nuclei and can be involved in the adaptive response.
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Affiliation(s)
- Bert Blaauw
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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Clanton TL, Hogan MC, Gladden LB. Regulation of cellular gas exchange, oxygen sensing, and metabolic control. Compr Physiol 2013; 3:1135-90. [PMID: 23897683 DOI: 10.1002/cphy.c120030] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cells must continuously monitor and couple their metabolic requirements for ATP utilization with their ability to take up O2 for mitochondrial respiration. When O2 uptake and delivery move out of homeostasis, cells have elaborate and diverse sensing and response systems to compensate. In this review, we explore the biophysics of O2 and gas diffusion in the cell, how intracellular O2 is regulated, how intracellular O2 levels are sensed and how sensing systems impact mitochondrial respiration and shifts in metabolic pathways. Particular attention is paid to how O2 affects the redox state of the cell, as well as the NO, H2S, and CO concentrations. We also explore how these agents can affect various aspects of gas exchange and activate acute signaling pathways that promote survival. Two kinds of challenges to gas exchange are also discussed in detail: when insufficient O2 is available for respiration (hypoxia) and when metabolic requirements test the limits of gas exchange (exercising skeletal muscle). This review also focuses on responses to acute hypoxia in the context of the original "unifying theory of hypoxia tolerance" as expressed by Hochachka and colleagues. It includes discourse on the regulation of mitochondrial electron transport, metabolic suppression, shifts in metabolic pathways, and recruitment of cell survival pathways preventing collapse of membrane potential and nuclear apoptosis. Regarding exercise, the issues discussed relate to the O2 sensitivity of metabolic rate, O2 kinetics in exercise, and influences of available O2 on glycolysis and lactate production.
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Affiliation(s)
- T L Clanton
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA.
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Masschelein E, Van Thienen R, D'Hulst G, Hespel P, Thomis M, Deldicque L. Acute environmental hypoxia induces LC3 lipidation in a genotype-dependent manner. FASEB J 2013; 28:1022-34. [PMID: 24200883 DOI: 10.1096/fj.13-239863] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hypoxia-induced muscle wasting is a phenomenon often described with prolonged stays at high altitude, which has been attributed to altered protein metabolism. We hypothesized that acute normobaric hypoxia would induce a negative net protein balance by repressing anabolic and activating proteolytic signaling pathways at rest and postexercise and that those changes could be partially genetically determined. Eleven monozygotic twins participated in an experimental trial in normoxia and hypoxia (10.7% O2). Muscle biopsy samples were obtained before and after a 20-min moderate cycling exercise. In hypoxia at rest, autophagic flux was increased, as indicated by an increased microtubule-associated protein 1 light chain 3 type II/I (LC3-II/I) ratio (+25%) and LC3-II expression (+60%) and decreased p62/SQSTM1 expression (-25%; P<0.05), whereas exercise reversed those changes to a level similar to that with normoxia except for p62/SQSTM1, which was further decreased (P<0.05). Hypoxia also increased Bnip3 (+34%) and MAFbx (+18%) mRNA levels as well as REDD1 expression (+439%) and AMP-activated protein kinase phosphorylation (+22%; P<0.05). Among the molecular responses to hypoxia and/or exercise, high monozygotic similarity was found for REDD1, LC3-II, and LC3-II/I (P<0.05). Our results indicate that environmental hypoxia modulates protein metabolism at rest and after moderate exercise by primarily increasing markers of protein breakdown and, more specifically, markers of the autophagy-lysosomal system, with a modest genetic contribution.
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Affiliation(s)
- Evi Masschelein
- 1Exercise Physiology Research Group, Department of Kinesiology, KU Leuven, Tervuursevest 101, B-3001 Leuven, Belgium.
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12
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Cerretelli P. Career perspective: Paolo Cerretelli. EXTREME PHYSIOLOGY & MEDICINE 2013; 2:13. [PMID: 24438551 PMCID: PMC3710087 DOI: 10.1186/2046-7648-2-13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 03/28/2013] [Indexed: 11/30/2022]
Abstract
This article is an autobiographical account of my career as a human physiologist. I have spent 55 years traversing mountains, continents, seas, and skies, carrying out research in the laboratories of several international institutions as well as in the field. My scientific roots, approach to the mountains and altitude populations, both in Europe and in Asia, together with an account of my experimental studies at altitude, including extreme conditions, shall be presented together with pertinent occasional reflections of a personal nature.
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Affiliation(s)
- Paolo Cerretelli
- Istituto di Bioimmagini e Fisiologia Molecolare del Consiglio Nazionale delle Ricerche (C,N,R,), via Fratelli Cervi, 93, Segrate, Milan 20090, Italy.
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Abstract
Insufficient tissue oxygenation occurs in a wide range of physiological and pathological conditions. Reactive oxygen species (ROS) are physiological products of aerobic life and their accumulation affects aging. Chronic intermittent hypoxia can lead to oxidative stress that could predispose the organism to cumulative acceleration of the aging process.
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Affiliation(s)
- Camillo Di Giulio
- Department of Neurosciences and Imaging, University of Chieti, Italy.
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Meyer A, Zoll J, Charles AL, Charloux A, de Blay F, Diemunsch P, Sibilia J, Piquard F, Geny B. Skeletal muscle mitochondrial dysfunction during chronic obstructive pulmonary disease: central actor and therapeutic target. Exp Physiol 2013; 98:1063-78. [DOI: 10.1113/expphysiol.2012.069468] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Mo L, Wang Y, Geary L, Corey C, Alef MJ, Beer-Stolz D, Zuckerbraun BS, Shiva S. Nitrite activates AMP kinase to stimulate mitochondrial biogenesis independent of soluble guanylate cyclase. Free Radic Biol Med 2012; 53:1440-50. [PMID: 22892143 PMCID: PMC3477807 DOI: 10.1016/j.freeradbiomed.2012.07.080] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 07/20/2012] [Accepted: 07/30/2012] [Indexed: 01/19/2023]
Abstract
Nitrite, a dietary constituent and endogenous signaling molecule, mediates a number of physiological responses including modulation of ischemia/reperfusion injury, glucose tolerance, and vascular remodeling. Although the exact molecular mechanisms underlying nitrite's actions are unknown, the current paradigm suggests that these effects depend on the hypoxic reduction of nitrite to nitric oxide (NO). Mitochondrial biogenesis is a fundamental mechanism of cellular adaptation and repair. However, the effect of nitrite on mitochondrial number has not been explored. Herein, we report that nitrite stimulates mitochondrial biogenesis through a mechanism distinct from that of NO. We demonstrate that nitrite significantly increases cellular mitochondrial number by augmenting the activity of adenylate kinase, resulting in AMP kinase phosphorylation, downstream activation of sirtuin-1, and deacetylation of PGC1α, the master regulator of mitochondrial biogenesis. Unlike NO, nitrite-mediated biogenesis does not require the activation of soluble guanylate cyclase and results in the synthesis of more functionally efficient mitochondria. Further, we provide evidence that nitrite mediates biogenesis in vivo. In a rat model of carotid injury, 2 weeks of continuous oral nitrite treatment postinjury prevented the hyperproliferative response of smooth muscle cells. This protection was accompanied by a nitrite-dependent upregulation of PGC1α and increased mitochondrial number in the injured artery. These data are the first to demonstrate that nitrite mediates differential signaling compared to NO. They show that nitrite is a versatile regulator of mitochondrial function and number both in vivo and in vitro and suggest that nitrite-mediated biogenesis may play a protective role in the setting of vascular injury.
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Affiliation(s)
- Li Mo
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Yinna Wang
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Lisa Geary
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Catherine Corey
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Matthew J. Alef
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Donna Beer-Stolz
- Center for Biological Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Brian S. Zuckerbraun
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Sruti Shiva
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Corresponding Author: Department of Pharmacology & Chemical Biology Vascular Medicine Institute BST E1242 University of Pittsburgh Pittsburgh, PA 15261 Fax: (412) 648-3046 Tel: (412)383-5854
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Ultrastructural modifications in the mitochondria of hypoxia-adapted Drosophila melanogaster. PLoS One 2012; 7:e45344. [PMID: 23028948 PMCID: PMC3446896 DOI: 10.1371/journal.pone.0045344] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 08/21/2012] [Indexed: 01/05/2023] Open
Abstract
Chronic hypoxia (CH) occurs under certain physiological or pathological conditions, including in people who reside at high altitude or suffer chronic cardiovascular or pulmonary diseases. As mitochondria are the predominant oxygen-consuming organelles to generate ATP through oxidative phosphorylation in cells, their responses, through structural or molecular modifications, to limited oxygen supply play an important role in the overall functional adaptation to hypoxia. Here, we report the adaptive mitochondrial ultrastructural modifications and the functional impacts in a recently generated hypoxia-adapted Drosophila melanogaster strain that survives severe, otherwise lethal, hypoxic conditions. Using electron tomography, we discovered increased mitochondrial volume density and cristae abundance, yet also cristae fragmentation and a unique honeycomb-like structure in the mitochondria of hypoxia-adapted flies. The homeostatic levels of adenylate and energy charge were similar between hypoxia-adapted and naïve control flies and the hypoxia-adapted flies remained active under severe hypoxia as quantified by negative geotaxis behavior. The equilibrium ATP level was lower in hypoxia-adapted flies than those of the naïve controls tested under severe hypoxia that inhibited the motion of control flies. Our results suggest that the structural rearrangement in the mitochondria of hypoxia-adapted flies may be an important adaptive mechanism that plays a critical role in preserving adenylate homeostasis and metabolism as well as muscle function under chronic hypoxic conditions.
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Chaudhary P, Suryakumar G, Prasad R, Singh SN, Ali S, Ilavazhagan G. Chronic hypobaric hypoxia mediated skeletal muscle atrophy: role of ubiquitin–proteasome pathway and calpains. Mol Cell Biochem 2012; 364:101-13. [DOI: 10.1007/s11010-011-1210-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 12/21/2011] [Indexed: 12/28/2022]
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18
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Di Giulio C, Zara S, Cataldi A, Porzionato A, Pokorski M, De Caro R. Human Carotid Body HIF and NGB Expression During Human Development and Aging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 758:265-71. [DOI: 10.1007/978-94-007-4584-1_36] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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19
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Colombo E, Marconi C, Taddeo A, Cappelletti M, Villa ML, Marzorati M, Porcelli S, Vezzoli A, Della Bella S. Fast reduction of peripheral blood endothelial progenitor cells in healthy humans exposed to acute systemic hypoxia. J Physiol 2011; 590:519-32. [PMID: 22155931 DOI: 10.1113/jphysiol.2011.223032] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
There are hints that hypoxia exposure may affect the number of circulating endothelial progenitor cells (EPCs) in humans. To test this hypothesis, the concentration of EPCs was determined by flow cytometry in the peripheral blood of 10 young healthy adults before (0 h), at different times (0.5 h, 1 h, 2 h and 4 h) during a 4 h normobaric hypoxic breathing simulating 4100 m altitude, and in the following recovery breathing room air. Results were interpreted mainly on the basis of the changes in surface expression of CXC chemokine receptor-4 (CXCR-4, a chemokine receptor essential for EPC migration and homing) and the percentage of apoptotic cells, the plasmatic levels of markers of oxidative stress induced by hypoxic breathing. Compared to 0 h, the concentration of EPCs, identified as either CD45(dim)/CD34(+)/KDR(+) or CD45(dim)/CD34(+)/KDR(+)/CD133(+) cells, decreased from 337 ± 83 ml(-1) (mean ± SEM) to 223 ± 52 ml(-1) (0.5 h; P < 0.005) and 100 ± 37 ml(-1) (4 h; P < 0.005), and from 216 ± 91 to 161 ± 50 ml(-1) (0.5 h; P < 0.05) and 45 ± 23 ml(-1) (4 h; P < 0.005), respectively. Upon return to normoxia, their concentration increased slowly, and after 4 h was still lower than at 0 h (P < 0.05). During hypoxia, CXCR-4 expression and plasmatic stromal derived cell factor-1 (SDF-1) increased abruptly (0.5 h: +126% and +13%, respectively; P < 0.05), suggesting cell marginalization as a possible cause of the rapid hypoxia-induced EPC reduction. Moreover, hypoxia exposure induced an increase in EPC apoptosis and markers of oxidative stress, which was significantly evident only starting from 2 h and 4 h after hypoxia offset, respectively, suggesting that EPC apoptosis may contribute to the later phase of hypoxia-induced EPC reduction. Overall, these observations may provide new insights into the understanding of the mechanisms operated by EPCs to maintain endothelial homeostasis.
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Affiliation(s)
- Elena Colombo
- Department of Biomedical Sciences and Technologies, Laboratory of Immunology, University of Milan, Milan, Italy
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Doria C, Toniolo L, Verratti V, Cancellara P, Pietrangelo T, Marconi V, Paoli A, Pogliaghi S, Fanò G, Reggiani C, Capelli C. Improved V̇O2 uptake kinetics and shift in muscle fiber type in high-altitude trekkers. J Appl Physiol (1985) 2011; 111:1597-605. [PMID: 21868681 DOI: 10.1152/japplphysiol.01439.2010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The study investigated the effect of prolonged hypoxia on central [i.e., cardiovascular oxygen delivery (Q̇aO2)] and peripheral (i.e., O2 utilization) determinants of oxidative metabolism response during exercise in humans. To this aim, seven male mountaineers were examined before and immediately after the Himalayan Expedition Interamnia 8000–Manaslu 2008, lasting 43 days, among which, 23 days were above 5,000 m. The subjects showed a decrease in body weight ( P < 0.05) and of power output during a Wingate Anaerobic test ( P < 0.05) and an increase of thigh cross-sectional area ( P < 0.05). Absolute maximal O2 uptake (V̇O2max) did not change. The mean response time of V̇O2 kinetics at the onset of step submaximal cycling exercise was reduced significantly from 53.8 s ± 10.9 to 39.8 s ± 10.9 ( P < 0.05), whereas that of Q̇aO2 was not. Analysis of single fibers dissected from vastus lateralis biopsies revealed that the expression of slow isoforms of both heavy and light myosin subunits increased, whereas that of fast isoforms decreased. Unloaded shortening velocity of fibers was decreased significantly. In summary, independent findings converge in indicating that adaptation to chronic hypoxia brings about a fast-to-slow transition of muscle fibers, resulting in a faster activation of the mitochondrial oxidative metabolism. These results indicate that a prolonged and active sojourn in hypoxia may induce muscular ultrastructural and functional changes similar to those observed after aerobic training.
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Affiliation(s)
- C. Doria
- Department of Neurosciences and Imaging, University of Chieti-Pescara, Chieti
| | - L. Toniolo
- Department of Anatomy and Physiology, University of Padova
| | - V. Verratti
- Department of Neurosciences and Imaging, University of Chieti-Pescara, Chieti
| | - P. Cancellara
- Department of Anatomy and Physiology, University of Padova
| | - T. Pietrangelo
- Department of Neurosciences and Imaging, University of Chieti-Pescara, Chieti
| | - V. Marconi
- School of Exercise and Sport Sciences, University of Verona
| | - A. Paoli
- Department of Anatomy and Physiology, University of Padova
| | - S. Pogliaghi
- School of Exercise and Sport Sciences, University of Verona
| | - G. Fanò
- Department of Neurosciences and Imaging, University of Chieti-Pescara, Chieti
| | - C. Reggiani
- Department of Anatomy and Physiology, University of Padova
- CNR, Institute of Neuroscience, Padova; and
| | - C. Capelli
- School of Exercise and Sport Sciences, University of Verona
- CeRiSM, Rovereto, Trento, Italy
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21
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Cerretelli P, Gelfi C. Energy metabolism in hypoxia: reinterpreting some features of muscle physiology on molecular grounds. Eur J Appl Physiol 2010; 111:421-32. [PMID: 20352258 DOI: 10.1007/s00421-010-1399-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2010] [Indexed: 02/03/2023]
Abstract
An holistic approach for interpreting classical data on the adaptation of the animal and, particularly, of the human body to hypoxic stress was promoted by the discovery of HIF-1, the "master regulator" of cell hypoxic signaling. Mitochondrial production of ROS stabilizes the O(2)-regulated HIF-1α subunit of the HIF-1 dimer promoting transaction functions in a large number of potential target genes, activating transcription of sequences into RNA and, eventually, protein production. The aim of the present preliminary study is to assess whether adaptive changes in oxygen sensing and metabolic signaling, particularly in the control of energy turnover known to occur in cultured cells exposed to hypoxia, are detectable also in the muscles of animals and man. For the present analysis, data obtained from the proteome of the rat gastrocnemius and of the vastus lateralis muscle of humans together with functional measurements were compared with homologous data from hypoxic cultured cells. In particular, the following variables were assessed: (1) the role of stress response proteins in the maintenance of ROS homeostasis, (2) the activity of the PDK1 gene on the shunting of pyruvate away from the TCA cycle in rodents and in humans, (3) the COX-4/COX-2 ratio in hypoxic rodents, (4) the overall efficiency of oxidative phosphorylation in humans during exercise in hypoxia, (5) some features of muscle mitochondrial autophagy in humans undergoing subchronic and chronic altitude exposure. Despite the limited number of observations and the differences in the experimental approach, some initial interesting results were obtained encouraging to pursue this innovative effort.
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Affiliation(s)
- Paolo Cerretelli
- Istituto di Bioimmagini e Fisiologia Molecolare del Consiglio Nazionale delle Ricerche (CNR), Palazzo LITA, Via Fratelli Cervi, 93, 20190, Segrate, Milan, Italy.
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22
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Murray AJ. Metabolic adaptation of skeletal muscle to high altitude hypoxia: how new technologies could resolve the controversies. Genome Med 2009; 1:117. [PMID: 20090895 PMCID: PMC2808733 DOI: 10.1186/gm117] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In most tissues of the body, cellular ATP production predominantly occurs via mitochondrial oxidative phosphorylation of reduced intermediates, which are in turn derived from substrates such as glucose and fatty acids. In order to maintain ATP homeostasis, and therefore cellular function, the mitochondria require a constant supply of fuels and oxygen. In many disease states, or in healthy individuals at altitude, tissue oxygen levels fall and the cell must meet this hypoxic challenge to maintain energetics and limit oxidative stress. In humans at altitude and patients with respiratory disease, loss of skeletal muscle mitochondrial density is a consistent finding. Recent studies that have used cultured cells and genetic mouse models have elucidated a number of elegant adaptations that allow cells with a diminished mitochondrial population to function effectively in hypoxia. This article reviews these findings alongside studies of hypoxic human skeletal muscle, putting them into the context of whole-body physiology and acclimatization to high-altitude hypoxia. A number of current controversies are highlighted, which may eventually be resolved by a systems physiology approach that considers the time-or tissue-dependent nature of some adaptive responses. Future studies using high-throughput metabolomic, transcriptomic, and proteomic technologies to investigate hypoxic skeletal muscle in humans and animal models could resolve many of these controversies, and a case is therefore made for the integration of resulting data into computational models that account for factors such as duration and extent of hypoxic exposure, subjects' backgrounds, and whether data have been acquired from active or sedentary individuals. An integrated and more quantitative understanding of the body's metabolic response to hypoxia and the conditions under which adaptive processes occur could reveal much about the ways that tissues function in the very many disease states where hypoxia is a critical factor.
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Affiliation(s)
- Andrew J Murray
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
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23
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Pistilli EE, Bogdanovich S, Mosqueira M, Lachey J, Seehra J, Khurana TS. Pretreatment with a soluble activin type IIB receptor/Fc fusion protein improves hypoxia-induced muscle dysfunction. Am J Physiol Regul Integr Comp Physiol 2009; 298:R96-R103. [PMID: 19864340 DOI: 10.1152/ajpregu.00138.2009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypoxia, or reduced oxygen, occurs in a variety of clinical and environmental situations. Hypoxic exposure is associated with decreased muscle mass and a concomitant reduction in exercise capacity, although the exact mechanisms are not completely understood. The activin type IIB receptor (ActRIIB) is a receptor for transforming growth factor-beta (TGFbeta) superfamily members that are involved in the negative regulation of lean tissue mass. Given that hypoxia has negative effects on muscle mass and function and that modulation of the ActRIIB has been shown to increase muscle mass, we tested the hypothesis that pharmacological targeting of the ActRIIB for 2 wk would attenuate the loss of muscle mass and function in mice after exposure to normobaric hypoxia. ActRIIB modulation was achieved using a soluble activin receptor/Fc fusion protein (sActRIIB) in mice housed in a hypoxic chamber for 1 or 2 wk. Hypoxia induced a reduction in body weight in PBS- and sActRIIB-treated mice, although sActRIIB-treated mice remained larger throughout the hypoxic exposure. The absolute forces generated by extensor digitorum longus muscles were also significantly greater in sActRIIB- than PBS-treated mice and were more resistant to eccentric contraction-induced force drop after eccentric lengthening contractions. In summary, sActRIIB pretreatment attenuated hypoxia-induced muscle dysfunction. These data suggest that targeting the ActRIIB is an effective strategy to counter hypoxia-induced muscle dysfunction and to preacclimatize to hypoxia in clinical or high-altitude settings.
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Affiliation(s)
- Emidio E Pistilli
- Department of Physiology and Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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24
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Abstract
The ascent of humans to the summits of the highest peaks on Earth initiated a spurt of explorations into the physiological consequences of physical activity at altitude. The past three decades have demonstrated that the resetting of respiratory and cardiovascular control with chronic exposure to altitudes above 4000 m is accompanied by important structural-functional adjustments of skeletal muscle. The fully altitude-adapted phenotype preserves energy charge at reduced aerobic capacity through the promotion of anaerobic substrate flux and tighter metabolic control, often at the expense of muscle mass. In seeming contrast, intense physical activity at moderate hypoxia (2500 to 4000 m) modifies this response in both low and high altitude natives through metabolic compensation by elevating local aerobic capacity and possibly preventing muscle fiber atrophy. The combined use of classical morphometry and contemporary proteomic technology provides a highly resolved picture of the temporal control of hypoxia-induced muscular adaptations. The muscle proteome signature identifies mitochondrial autophagy and protein degradation as prime adaptive mechanisms to passive altitude exposure and ascent to extreme altitude. Protein measures also explain the lactate paradox by a sparing of glycolytic enzymes from general muscle wasting. Enhanced mitochondrial and angiogenic protein expression in human muscle with exercise up to 4000 m is related to the reduction in intramuscular oxygen content below 1% (8 torr), when the master regulator of hypoxia-dependent gene expression, HIF-1alpha, is stabilized. Accordingly, it is proposed here that the catabolic consequences of chronic hypoxia exposure reflect the insufficient activation of hypoxia-sensitive signaling and the suppression of energy-consuming protein translation.
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Affiliation(s)
- Martin Flueck
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK.
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25
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Cerretelli P, Marzorati M, Marconi C. Muscle Bioenergetics and Metabolic Control at Altitude. High Alt Med Biol 2009; 10:165-74. [DOI: 10.1089/ham.2008.1096] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Paolo Cerretelli
- IBFM-Section of Physiology, National Research Council, Palazzo LITA, via Fratelli Cervi 93, I-20090 Segrate (Milan), Italy
| | - Mauro Marzorati
- IBFM-Section of Physiology, National Research Council, Palazzo LITA, via Fratelli Cervi 93, I-20090 Segrate (Milan), Italy
| | - Claudio Marconi
- IBFM-Section of Physiology, National Research Council, Palazzo LITA, via Fratelli Cervi 93, I-20090 Segrate (Milan), Italy
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26
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Physiological carotid body denervation during aging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 648:257-63. [PMID: 19536488 DOI: 10.1007/978-90-481-2259-2_29] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aging is characterized by a lower homeostatic capacity and the carotid body (CB) plays an important role during aging. Here, we sought to elucidate whether the aging effects on the oxygen-sensitive mechanisms in CB cells occur through a reduction of the contact surfaces in the synaptic junctions. The hypothesis was that the CB would undergo a "physiological denervation" in old age. Two groups of male Wistar rats, young (2-3 months old) and senescent (22 months old) were used. CBs were rapidly dissected and the specimens were subjected to a routine transmission electron microscopic procedure. Expressions of HIF-1 proportional, variant, VEGF and NOS-1 were evaluated by immunohistochemical analysis. Our results show that in the old CB, HIF-1 proportional, variant, VEGF and NOS-1 expressions decrease. The cell volume, the number of mitochondria and that of dense-cored vesicles were reduced, and the nucleus shrank. There also was an accumulation of lipofuscin and a proliferation of extracellular matrix. Most importantly, there were fewer synaptic connections between chemoreceptor cells. The total number of synapses observed in all electronograms decreased from 125 in the young to 28 in the old CB. These results suggest the aging CB undergoes a "physiological denervation" leading to a reduction in homeostatic capacity. The age-related reduction of synaptic junctions may be a self-protective mechanism through which cells buffer themselves against reactive oxygen species accumulation during aging.
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27
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Hoppeler H, Klossner S, Vogt M. Training in hypoxia and its effects on skeletal muscle tissue. Scand J Med Sci Sports 2008; 18 Suppl 1:38-49. [PMID: 18665951 DOI: 10.1111/j.1600-0838.2008.00831.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
It is well established that local muscle tissue hypoxia is an important consequence and possibly a relevant adaptive signal of endurance exercise training in humans. It has been reasoned that it might be advantageous to increase this exercise stimulus by working in hypoxia. However, as long-term exposure to severe hypoxia has been shown to be detrimental to muscle tissue, experimental protocols were developed that expose subjects to hypoxia only for the duration of the exercise session and allow recovery in normoxia (live low-train high or hypoxic training). This overview reports data from 27 controlled studies using some implementation of hypoxic training paradigms. Hypoxia exposure varied between 2300 and 5700 m and training duration ranged from 10 days to 8 weeks. A similar number of studies was carried out on untrained and on trained subjects. Muscle structural, biochemical and molecular findings point to a specific role of hypoxia in endurance training. However, based on the available data on global estimates of performance capacity such as maximal oxygen uptake (VO2max) and maximal power output (Pmax), hypoxia as a supplement to training is not consistently found to be of advantage for performance at sea level. There is some evidence mainly from studies on untrained subjects for an advantage of hypoxic training for performance at altitude. Live low-train high may be considered when altitude acclimatization is not an option.
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Affiliation(s)
- H Hoppeler
- Department of Anatomy, Institute of Anatomy, University of Bern, Bern, Switzerland.
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28
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CHEN KT, CHEN YY, WU HJ, CHANG CK, LEE WT, LU YY, LIU CC, YANG RS, LIN JC. Decreased anaerobic performance and hormone adaptation after expedition to Peak Lenin. Chin Med J (Engl) 2008. [DOI: 10.1097/00029330-200811020-00004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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29
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Lynn EG, Lu Z, Minerbi D, Sack MN. The regulation, control, and consequences of mitochondrial oxygen utilization and disposition in the heart and skeletal muscle during hypoxia. Antioxid Redox Signal 2007; 9:1353-61. [PMID: 17627469 DOI: 10.1089/ars.2007.1700] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The major oxygen-dependent function of mitochondria partitions molecular oxygen between oxidative phosphorylation and reactive oxygen species generation. When oxygen becomes limiting, the modulation of mitochondrial function plays an important role in overall biologic adaptation. This review focuses on mitochondrial biology in the heart and skeletal muscle during hypoxia. The disparate mitochondrial responses discussed appear to be dependent on the degree of hypoxia, on the age at exposure to hypoxia, and on the duration of exposure. These hypoxia-induced changes include modulation in mitochondrial respiratory capacity; activation of the mitochondrial biogenesis regulatory program; induction of mitochondrial antioxidant defense systems; regulation of antiapoptotic mitochondrial proteins, and modulation of mitochondrial sensitivity to permeability transition. The mitochondria-derived reactive oxygen species signal-transduction events in response to hypoxia also are reviewed. The cardiac and skeletal muscle phenotypic signatures that result from mitochondrial adaptations include an amelioration of resistance to cardiac ischemia and modulations in exercise capacity and oxidative fuel preference. Overall, the data demonstrate the plasticity in mitochondrial regulation and function that facilitates adaptations to a limited oxygen supply. Moreover, data supporting the role of mitochondria as oxygen-sensing organelles, integrated into global cellular signal transduction are discussed.
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Affiliation(s)
- Edward G Lynn
- Cardiology Branch, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1454, USA
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30
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Abstract
The existence of hypoxia-induced reactive oxygen species (ROS) production remains controversial. However, numerous observations with a variety of methods and in many cells and tissue types are supportive of this idea. Skeletal muscle appears to behave much like heart in that in the early stages of hypoxia there is a transient elevation in ROS, whereas in chronic exposure to very severe hypoxia there is evidence of ongoing oxidative stress. Important remaining questions that are addressed in this review include the following. Are there levels of PO2 in skeletal muscle, typical of physiological or mildly pathophysiological conditions, that are low enough to induce significant ROS production? Does the ROS associated with muscle contractile activity reflect imbalances in oxygen uptake and demand that drive the cell to a more reduced state? What are the possible molecular mechanisms by which ROS may be elevated in hypoxic skeletal muscle? Is the production of ROS in hypoxia of physiological significance, both with respect to cell signaling pathways promoting cell function and with respect to damaging effects of long-term exposure? Discussion of these and other topics leads to general conclusions that hypoxia-induced ROS may be a normal physiological response to imbalance in oxygen supply and demand or environmental stress and may play a yet undefined role in normal response mechanisms to these stimuli. However, in chronic and extreme hypoxic exposure, muscles may fail to maintain a normal redox homeostasis, resulting in cell injury or dysfunction.
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Affiliation(s)
- Thomas L Clanton
- Department of Internal Medicine, The Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University College of Medicine, 473 W. 12th, Columbus, OH 43210, USA.
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31
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Marconi C, Marzorati M, Cerretelli P. Work capacity of permanent residents of high altitude. High Alt Med Biol 2006; 7:105-15. [PMID: 16764524 DOI: 10.1089/ham.2006.7.105] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Tibetan and Andean natives at altitude have allegedly a greater work capacity and stand fatigue better than acclimatized lowlanders. The principal aim of the present review is to establish whether convincing experimental evidence supports this belief and, should this be the case, to analyze the possible underlying mechanisms. The superior work capacity of high altitude natives is not based on differences in maximum aerobic power (V(O2 peak)), mL kg(-1)min(-1)). In fact, average V (O2 peak) of both Tibetan and Andean natives at altitude is only slightly, although not significantly, higher than that of Asian or Caucasian lowlanders resident for more than 1 yr between 3400 and 4700 m (Tibetans, n = 152, vs. Chinese Hans, n = 116: 42.4 +/- 3.4 vs. 39.2 +/- 2.6 mL kg(-1)min(-1), mean +/- SE; Andeans, n = 116, vs. Caucasians, n = 70: 47.1 +/- 1.7 vs. 41.6 +/- 1.2 mL kg(-1)min(-1)). However, compared to acclimatized lowlanders, Tibetans appear to be characterized by a better economy of cycling, walking, and running on a treadmill. This is possibly due to metabolic adaptations, such as increased muscle myoglobin content and antioxidant defense. All together, the latter changes may enhance the efficiency of the muscle oxidative metabolic machinery, thereby supporting a better prolonged submaximal performance capacity compared to lowlanders, despite equal V(O2 peak). With regard to Andeans, data on exercise efficiency is scanty and controversial and, at present, no conclusion can be drawn as to the origin of their superior performance.
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32
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Métabolisme des nutriments au cours de l'insuffisance respiratoire chronique. NUTR CLIN METAB 2006. [DOI: 10.1016/j.nupar.2006.10.179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Koechlin C, Maltais F, Saey D, Michaud A, LeBlanc P, Hayot M, Préfaut C. Hypoxaemia enhances peripheral muscle oxidative stress in chronic obstructive pulmonary disease. Thorax 2005; 60:834-41. [PMID: 15964914 PMCID: PMC1747208 DOI: 10.1136/thx.2004.037531] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Because oxidative stress affects muscle function, the underlying mechanism to explain exercise induced peripheral muscle oxidative stress in patients with chronic obstructive pulmonary disease (COPD) is clinically relevant. This study investigated whether chronic hypoxaemia in COPD worsens peripheral muscle oxidative stress and whether an abnormal muscle inflammatory process is associated with it. METHODS Nine chronically hypoxaemic and nine non-hypoxaemic patients performed repeated knee extensions until exhaustion. Biopsy specimens were taken from the vastus lateralis muscle before and 48 hours after exercise. Muscle oxidative stress was evaluated by lipid peroxidation (lipofuscin and thiobarbituric acid reactive substances (TBARs)) and oxidised proteins. Inflammation was evaluated by quantifying muscle neutrophil and tumour necrosis factor (TNF)-alpha levels. RESULTS When both groups were taken together, arterial oxygen pressure was positively correlated with quadriceps endurance time (n = 18, r = 0.57; p < 0.05). At rest, quadriceps lipofuscin inclusions were significantly greater in hypoxaemic patients than in non-hypoxaemic patients (2.9 (0.2) v 2.0 (0.3) inclusions/fibre; p < 0.05). Exercise induced a greater increase in muscle TBARs and oxidised proteins in hypoxaemic patients than in non-hypoxaemic patients (40.6 (9.1)% v 10.1 (5.8)% and 51.2 (11.9)% v 3.7 (12.2)%, respectively, both p = 0.01). Neutrophil levels were significantly higher in hypoxaemic patients than in non-hypoxaemic patients (53.1 (11.6) v 21.5 (11.2) counts per fibre x 10(-3); p < 0.05). Exercise did not alter muscle neutrophil levels in either group. Muscle TNF-alpha was not detected at baseline or after exercise. CONCLUSION Chronic hypoxaemia was associated with lower quadriceps endurance time and worsened muscle oxidative stress at rest and after exercise. Increased muscle neutrophil levels could be a source of the increased baseline oxidative damage. The involvement of a muscle inflammatory process in the exercise induced oxidative stress of patients with COPD remains to be shown.
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Affiliation(s)
- C Koechlin
- Laboratoire de Physiologie des Interactions, Service Central de Physiologie Clinique, Hôpital Arnaud de Villeneuve, 34295 Montpellier cedex 5, France.
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34
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Di Giulio C, Bianchi G, Cacchio M, Artese L, Rapino C, Macrì MA, Di Ilio C. Oxygen and life span: chronic hypoxia as a model for studying HIF-1α, VEGF and NOS during aging. Respir Physiol Neurobiol 2005; 147:31-8. [PMID: 15848121 DOI: 10.1016/j.resp.2005.01.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 12/21/2004] [Accepted: 01/12/2005] [Indexed: 10/25/2022]
Abstract
To test if oxygen sensitive mechanisms are affected by hypoxia, we studied hypoxia inducible factor-1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS) expression by immunohistochemical analysis in young and old rat carotid bodies (CBs) using hypoxia as a model for modulating aging. Four groups of male age-matched Wistar rats (3 and 24 months) were used. Two groups were kept in room air, and two groups were kept under chronic intermittent hypoxia for 12 days. In aged carotid body and in hypoxia the increased expression of HIF-1alpha, VEGF, iNOS is less evident as compared to the young one. Electron microscopy sections showed a reduced mitochondrial number and area in the aged CBs and during hypoxia. Less responsiveness to hypoxia could be evidenced in the aged rats as compared to the young rats, suggesting an age dependency of the oxygen sensitive mechanisms.
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Affiliation(s)
- Camillo Di Giulio
- Department of Biomedical Sciences, Via dei Vestini 31, G. d'Annunzio University, 66013 Chieti-Pescara, Italy.
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35
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Raguso CA, Guinot SL, Janssens JP, Kayser B, Pichard C. Chronic hypoxia: common traits between chronic obstructive pulmonary disease and altitude. Curr Opin Clin Nutr Metab Care 2004; 7:411-7. [PMID: 15192444 DOI: 10.1097/01.mco.0000134372.78438.09] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Loss of body mass and exercise intolerance are common findings in chronic obstructive pulmonary disease and are often difficult to reverse despite optimal nutritional intake. Similar findings have been reported in healthy individuals during high-altitude exposure. The role of hypoxia in modulating metabolism has been largely investigated in vitro and in animal studies. More fragmentary is the knowledge regarding hypoxia effects on in-vivo human metabolism. This paper reviews recent literature regarding the effects of chronic exposure to hypoxia on metabolism, particularly comparing chronic obstructive pulmonary disease patients with humans exposed to high altitude. RECENT FINDINGS Hypoxia has important metabolic effects. Many oxygen-sensitive regulatory mechanisms work through hypoxia inducible factor 1, and recent literature regarding the hypoxic stimulus and its pathological implications deals largely with hypoxia inducible factor 1-related findings. Hypoxia inducible factor 1 is pivotal in the adaptation to chronic hypoxia: it induces gene expression for fructose-2-6-biphosphatase, an enzyme switching glucose metabolism towards glycolysis, allowing energy production in anaerobic conditions. Hypoxia inducible factor 1 is also involved in the development of anorexia because it induces the promoter of the leptin gene. Particularly important for future therapeutic implications are findings related to hypoxia inducible factor 1 polymorphism and interaction with other molecules, especially estrogens, in the clinical evolution of disease. SUMMARY Malnutrition is a worsening factor in chronic obstructive pulmonary disease. Similarities between chronic obstructive pulmonary disease and altitude exposure point to the importance of hypoxia in this regard. A better understanding of the underlying mechanisms will help to find alternative therapeutic approaches.
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Affiliation(s)
- Comasia A Raguso
- Division of Clinical Nutrition, University Hospital, Geneva, Switzerland
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Marconi C, Marzorati M, Grassi B, Basnyat B, Colombini A, Kayser B, Cerretelli P. Second generation Tibetan lowlanders acclimatize to high altitude more quickly than Caucasians. J Physiol 2004; 556:661-71. [PMID: 14766936 PMCID: PMC1664949 DOI: 10.1113/jphysiol.2003.059188] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 12/03/2003] [Accepted: 02/05/2004] [Indexed: 11/08/2022] Open
Abstract
Tibetan highlanders develop at altitude peak aerobic power levels close to those of Caucasians at sea level. In order to establish whether this feature is genetic and, as a consequence, retained by Tibetan lowlanders, altitude-induced changes of peak aerobic performance were assessed in four groups of volunteers with different ethnic, altitude exposure and fitness characteristics, i.e. eight untrained second-generation Tibetans (Tib 2) born and living at 1300 m; seven altitude Sherpas living at approximately 2800-3500 m; and 10 untrained and five trained Caucasians. Measurements were carried out at sea level or at Kathmandu (1300 m, Nepal) (PRE), and after 2-4 (ALT1), 14-16 (ALT2), and 26-28 (ALT3) days at 5050 m. At ALT3, of untrained and trained Caucasians was -31% and -46%, respectively. By contrast, of Tib 2 and Sherpas was -8% and -15%, respectively. At ALT3, peak heart rate (HR(peak)) of untrained and trained Caucasians was 148 +/- 11 and 149 +/- 7 beats min(-1), respectively; blood oxygen saturation at peak exercise was 76 +/- 6% and 73 +/- 6%, and haemoglobin concentration ([Hb]) was 19.4 +/- 1.0 and 18.6 +/- 1.2 g dl(-1), respectively. Compared to Caucasians, Tib 2 and Sherpas exhibited at ALT3 higher HR(peak) (179 +/- 9 and 171 +/- 4 beats min(-1), P < 0.001), lower [Hb] (16.6 +/- 0.6 and 17.4 +/- 0.9 g dl(-1), respectively, P < 0.001), and slightly but non-significantly greater average values (82 +/- 6 and 80 +/- 7%). The above findings and the time course of adjustment of the investigated variables suggest that Tibetan lowlanders acclimatize to chronic hypoxia more quickly than Caucasians, independent of the degree of fitness of the latter.
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Affiliation(s)
- Claudio Marconi
- I.B.F.M.-Consiglio Nazionale delle Ricerche, L.I.T.A, Via Fratelli Cervi 93, I-20090 SEGRATE (Milan), Italy.
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Gelfi C, De Palma S, Ripamonti M, Eberini I, Wait R, Bajracharya A, Marconi C, Schneider A, Hoppeler H, Cerretelli P. New aspects of altitude adaptation in Tibetans: a proteomic approach. FASEB J 2004; 18:612-4. [PMID: 14734630 DOI: 10.1096/fj.03-1077fje] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A prolonged sojourn above 5500 m induces muscle deterioration and accumulation of lipofuscin in Caucasians, probably because of overproduction of reactive oxygen species (ROS). Because Sherpas, who live at high altitude, have very limited muscle damage, it was hypothesized that Himalayan natives possess intrinsic mechanisms protecting them from oxidative damage. This possibility was investigated by comparing the muscle proteomes of native Tibetans permanently residing at high altitude, second-generation Tibetans born and living at low altitude, and Nepali control subjects permanently residing at low altitude, using 2D gel electrophoresis and mass spectrometry. Seven differentially regulated proteins were identified: glutathione-S-transferase P1-1, which was 380% and 50% overexpressed in Tibetans born and living at high and low altitude, respectively; Delta2-enoyl-CoA-hydratase, which was up-regulated in both Tibetan groups; glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase, which were both slightly down-regulated in Tibetans born and living at high altitude; phosphoglycerate mutase, which was 50% up-regulated in the native Tibetans; NADH-ubiquinone oxidoreductase, slightly overexpressed in Tibetans born and living at high altitude; and myoglobin, which was overexpressed in both Tibetan groups. We concluded that Tibetans at high altitude, and to some extent, those born and living at low altitude, are protected from ROS-induced tissue damage and possess specific metabolic adaptations.
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Affiliation(s)
- Cecilia Gelfi
- Institute of Molecular Bioimaging and Physiology, CNR, Segrate, Italy.
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Bianchi G, Cacchio M, Artese L, Ferrero G, Rapino C, Grilli A, Felaco M, Di Giulio C. Carotid body nitric oxide activity in spontaneously diabetic BB rat. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 536:359-66. [PMID: 14635689 DOI: 10.1007/978-1-4419-9280-2_47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Affiliation(s)
- Giuseppina Bianchi
- Department of Biomedical Sciences, Centre of Excellence for Aging, G. d'Annunzio University, Chieti, Italy
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Di Giulio C, Cacchio M, Bianchi G, Rapino C, Di Ilio C. Selected contribution: Carotid body as a model for aging studies: is there a link between oxygen and aging? J Appl Physiol (1985) 2003; 95:1755-8. [PMID: 12871967 DOI: 10.1152/japplphysiol.00406.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The carotid body (CB) is the site in the body that triggers awareness of changes in blood oxygen pressure. Aging is characterized by a decrease in oxygen supply to tissues, in reduction of tissue Po2, and in the activity of several enzymes and metabolic factors. The ventilatory response to hypoxia is attenuated with aging related to the age-dependent structure modifications including the basal reduction of oxygen requirements. The aged CB shows an increase in extracellular matrix, a reduction in number and volume of type I cells, and a reduction in volume of mitochondria that was consistent with and similar to that during chronic hypoxia; this phenomenon seems to operate also during aging as shown by the reduced volume of mitochondria in the aged CB. During chronic hypoxia, CB hypertrophy is less evident in aged CB than in young CB. Therefore, hypoxia and aging seem to share some type of link at different cell sites. CB represents an experimental model adequate for studying aging processes because of its high blood flow and metabolism, and thus it serves as a means to understanding the oxygen modulation of the aging process.
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Affiliation(s)
- C Di Giulio
- Univ. G. d'Annunzio, Dept. of Biomedical Sciences, Via dei Vestini 31, 66100 Chieti, Italy.
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Cerretelli P, Samaja M. Acid-base balance at exercise in normoxia and in chronic hypoxia. Revisiting the "lactate paradox". Eur J Appl Physiol 2003; 90:431-48. [PMID: 14504942 DOI: 10.1007/s00421-003-0928-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/25/2003] [Indexed: 10/26/2022]
Abstract
Transitions between rest and work, in either direction, and heavy exercise loads are characterized by changes of muscle pH depending on the buffer power and capacity of the tissues and on the metabolic processes involved. Among the latter, in chronological sequence: (1). aerobic glycolysis generates sizeable amounts of lactate and H(+) by way of the recently described, extremely fast (20-100 ms) "glycogen shunt" and of the excess of glycolytic pyruvate supply; (2). hydrolysis of phosphocreatine, tightly coupled with that of ATP in the Lohmann reaction, is known to consume protons, a process undergoing reversal during recovery; (3). anaerobic glycolysis sustaining ATP production in supramaximal exercise as well as in conditions of hypoxia and ischemia, is responsible for the accumulation of large amounts of lactic acid (up to 1 mol for the whole body). The handling of metabolic acids, i.e., acid-base regulation, occurs both in blood and in tissues, mainly in muscles which are the main producers and consumers of lactic acid. The role of both blood and muscle bicarbonate and non-bicarbonate buffers as well as that of lactate/H(+) cotransport mechanisms is analyzed in relation to acid-base homeostasis in the course of exercise. A section of the review deals with the analysis of the acid-base state of humans exposed to chronic hypoxia. Particular emphasis is put on anaerobic glycolysis. In this context, the so-called lactate paradox is revisited and interpreted on the basis of the most recent findings on exercise at altitude.
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Affiliation(s)
- Paolo Cerretelli
- Department of Sciences and Biomedical Technologies, LITA, University of Milan, Via F lli Cervi 93, 20090, SEGRATE, Milano, Italy.
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Flück M, Hoppeler H. Molecular basis of skeletal muscle plasticity--from gene to form and function. Rev Physiol Biochem Pharmacol 2003; 146:159-216. [PMID: 12605307 DOI: 10.1007/s10254-002-0004-7] [Citation(s) in RCA: 292] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle shows an enormous plasticity to adapt to stimuli such as contractile activity (endurance exercise, electrical stimulation, denervation), loading conditions (resistance training, microgravity), substrate supply (nutritional interventions) or environmental factors (hypoxia). The presented data show that adaptive structural events occur in both muscle fibres (myofibrils, mitochondria) and associated structures (motoneurons and capillaries). Functional adaptations appear to involve alterations in regulatory mechanisms (neuronal, endocrine and intracellular signalling), contractile properties and metabolic capacities. With the appropriate molecular techniques it has been demonstrated over the past 10 years that rapid changes in skeletal muscle mRNA expression occur with exercise in human and rodent species. Recently, gene expression profiling analysis has demonstrated that transcriptional adaptations in skeletal muscle due to changes in loading involve a broad range of genes and that mRNA changes often run parallel for genes in the same functional categories. These changes can be matched to the structural/functional adaptations known to occur with corresponding stimuli. Several signalling pathways involving cytoplasmic protein kinases and nuclear-encoded transcription factors are recognized as potential master regulators that transduce physiological stress into transcriptional adaptations of batteries of metabolic and contractile genes. Nuclear reprogramming is recognized as an important event in muscle plasticity and may be related to the adaptations in the myosin type, protein turnover, and the cytoplasma-to-myonucleus ratio. The accessibility of muscle tissue to biopsies in conjunction with the advent of high-throughput gene expression analysis technology points to skeletal muscle plasticity as a particularly useful paradigm for studying gene regulatory phenomena in humans.
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Affiliation(s)
- M Flück
- Institute of Anatomy, University of Bern, Bühlstrasse 26, 3000, Bern 9, Switzerland.
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Di Giulio C, Bianchi G, Cacchio M, Macrì MA, Ferrero G, Rapino C, Verratti V, Piccirilli M, Artese L. Carotid Body HIF-1α, VEGF and NOS Expression during Aging and Hypoxia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 536:603-10. [PMID: 14635718 DOI: 10.1007/978-1-4419-9280-2_76] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- Camillo Di Giulio
- Department of Biomedical Sciences, Centre of Excellence for Aging, G. d'Annunzio University, Chieti, Italy
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Allaire J, Maltais F, LeBlanc P, Simard PM, Whittom F, Doyon JF, Simard C, Jobin J. Lipofuscin accumulation in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease. Muscle Nerve 2002; 25:383-9. [PMID: 11870715 DOI: 10.1002/mus.10039] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exercise-induced oxidative stress has been reported in patients with chronic obstructive pulmonary disease (COPD) and may play a role in muscle fatigue. It is speculated that oxidative stress during exercise originates from the contracting muscles but this has not been documented. The accumulation of lipofuscin, a marker of cellular oxidative damage, was evaluated in the vastus lateralis muscle in 17 patients with COPD and 10 healthy subjects of similar age. Each subject performed a stepwise exercise test up to maximal capacity during which oxygen uptake (VO(2)) was measured. Resting and peak exercise blood gases were also obtained. Two indices of lipofuscin accumulation were used: lipofuscin inclusions/fiber ratio (LI/F) and lipofuscin inclusions/fiber cross-sectional area ratio (LI/CSA). These ratios were also determined for each specific fiber-type. LI/F (P < 0.01) and LI/CSA (P < 0.01) were greater in COPD compared to healthy subjects. LI/F and LI/CSA for all fiber types were also greater in COPD (P < 0.001). In both groups, LI/F (P < 0.001) and LI/CSA (P < 0.01) were higher in type I than in type II fibers. LI/F and LI/CSA did not correlate significantly with resting PaO(2) and SaO(2), peak VO(2), and DeltaPaO(2) and DeltaSaO(2) during exercise (P > 0.05). Increased lipofuscin accumulation, a marker of oxidative damage, was found in the vastus lateralis muscle in patients with COPD compared to healthy subjects. Oxidative damage of muscle tissue may thus be involved in skeletal muscle dysfunction and wasting in COPD.
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Affiliation(s)
- Joakim Allaire
- Centre de Recherche, Institut de Cardiologie et de Pneumologie de l'Université Laval, Hôpital Laval, 2725 Chemin Ste-Foy, Ste-Foy, Québec, G1V 4G5 Canada
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Mathieu-Costello O. Muscle adaptation to altitude: tissue capillarity and capacity for aerobic metabolism. High Alt Med Biol 2002; 2:413-25. [PMID: 11682021 DOI: 10.1089/15270290152608598] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Prolonged exposure to high altitude leads to reduced muscle mass and performance. The fall in muscle mass follows a reduction in fiber size, which at first was believed to be accompanied by increased fiber capillarization and aerobic enzymes. Subsequent studies showed that hypoxia alone does not alter capillary number and geometry in skeletal muscles of mammals at altitude. It was also found that alterations in fiber size and aerobic enzymes depend on a number of additional factors, including animal activity and the level of hypoxia (e.g., moderate vs. extreme altitude). With training at altitude, fiber capillary number and aerobic enzymes are increased, indicating that muscle potential for plasticity is conserved in hypoxia. Recent studies have also shown that capillary number and geometry are altered in muscles of several species of birds native or exposed to higher altitude; that is, that capillary growth can occur in skeletal muscle in response to chronic exposure to high altitude. In this mini review, we summarize these data and current knowledge on muscle capillary to fiber structural relationships and their implications for muscle aerobic function at altitude.
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Affiliation(s)
- O Mathieu-Costello
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0623, USA.
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Abstract
SUMMARY
This review reports on the effects of hypoxia on human skeletal muscle tissue. It was hypothesized in early reports that chronic hypoxia, as the main physiological stress during exposure to altitude, per se might positively affect muscle oxidative capacity and capillarity. However, it is now established that sustained exposure to severe hypoxia has detrimental effects on muscle structure. Short-term effects on skeletal muscle structure can readily be observed after 2 months of acute exposure of lowlanders to severe hypoxia, e.g. during typical mountaineering expeditions to the Himalayas. The full range of phenotypic malleability of muscle tissue is demonstrated in people living permanently at high altitude (e.g. at La Paz, 3600–4000m). In addition, there is some evidence for genetic adaptations to hypoxia in high-altitude populations such as Tibetans and Quechuas, who have been exposed to altitudes in excess of 3500m for thousands of generations. The hallmark of muscle adaptation to hypoxia in all these cases is a decrease in muscle oxidative capacity concomitant with a decrease in aerobic work capacity. It is thought that local tissue hypoxia is an important adaptive stress for muscle tissue in exercise training, so these results seem contra-intuitive. Studies have therefore been conducted in which subjects were exposed to hypoxia only during exercise sessions. In this situation, the potentially negative effects of permanent hypoxic exposure and other confounding variables related to exposure to high altitude could be avoided. Training in hypoxia results, at the molecular level, in an upregulation of the regulatory subunit of hypoxia-inducible factor-1 (HIF-1). Possibly as a consequence of this upregulation of HIF-1, the levels mRNAs for myoglobin, for vascular endothelial growth factor and for glycolytic enzymes, such as phosphofructokinase, together with mitochondrial and capillary densities, increased in a hypoxia-dependent manner. Functional analyses revealed positive effects on V̇O2max (when measured at altitude) on maximal power output and on lean body mass. In addition to the positive effects of hypoxia training on athletic performance, there is some recent indication that hypoxia training has a positive effect on the risk factors for cardiovascular disease.
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Affiliation(s)
- H Hoppeler
- Department of Anatomy, University of Bern, Bühlstrasse 26, CH-3000 Bern 9, Switzerland.
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Santilli SM, Tretinyak AS, Lee ES. Transarterial wall oxygen gradients at the deployment site of an intra-arterial stent in the rabbit. Am J Physiol Heart Circ Physiol 2000; 279:H1518-25. [PMID: 11009436 DOI: 10.1152/ajpheart.2000.279.4.h1518] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intimal hyperplasia, common at the deployment site of an intra-arterial stent, may be caused by artery wall hypoxia. The purpose of this study was to determine the effect of an intra-arterial stent on artery wall oxygen concentrations. Transarterial wall oxygen gradients were measured by microelectrode at stent deployment sites in New Zealand White rabbits. Thinned artery walls and decreased oxygen tensions were noted throughout the artery wall immediately following stent deployment with a return toward control values at 28 days. Angioplasty alone had no acute effect on artery wall oxygen concentrations. Larger stent deployment diameters yielded acutely lower artery wall oxygen tensions. Using a linear one-dimensional model for the oxygen profile, we noted that stent deployment resulted in acute changes in oxygen consumption in the inner artery wall that rapidly returned to control values. Changes were noted without differences in blood pressure or arterial blood oxygen concentrations. Oxygen delivery to and consumption within the artery wall are altered by intra-arterial stent deployment. A role for artery wall hypoxia in artery wall pathology at the deployment site of an intra-arterial stent is supported by these findings.
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Affiliation(s)
- S M Santilli
- Department of Surgery, Veterans Affairs Medical Center, Minneapolis 55417, USA
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Santilli SM, Wernsing SE, Lee ES. Transarterial wall oxygen gradients at a prosthetic vascular graft to artery anastomosis in the rabbit. J Vasc Surg 2000; 31:1229-39. [PMID: 10842160 DOI: 10.1067/mva.2000.104590] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PURPOSE Artery-wall hypoxia has been proposed to contribute to many kinds of artery-wall pathologic conditions, including atherosclerosis and intimal hyperplasia. Intimal hyperplasia is common at sites of arterial injury, including an anastomosis. The purpose of this study was to determine the effect of a prosthetic vascular graft (PVG)-to-artery anastomosis on the delivery of oxygen to the artery wall. METHODS The transarterial wall oxygen gradient in the infrarenal aorta of New Zealand White rabbits 2 mm distal to a PVG-to-artery anastomosis was measured with an oxygen microelectrode. RESULTS Oxygen tensions were significantly decreased in the outer artery wall immediately after the creation of the anastomosis and showed a further decrease in oxygen tensions at days 7 and 14, which correlated with the absence of a vasa vasorum. After day 14, the oxygen tensions gradually increased, returning to normal by postanastomosis day 42, correlating with a return of the vasa vasorum. These changes were noted without differences in blood pressure or arterial blood oxygen concentrations. CONCLUSION The delivery of oxygen to the artery wall is altered by the creation of a PVG-to-artery anastomosis. Low arterial oxygen tensions at a PVG-to-artery anastomosis support a role for artery-wall hypoxia in the formation of intimal hyperplasia at the site of a PVG-to-artery anastomosis.
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Affiliation(s)
- S M Santilli
- Department of Surgery, Veterans Affairs Medical Center, University of Minnesota, Minneapolis 55417, USA
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Affiliation(s)
- D Dayan
- Section of Oral Pathology and Oral Medicine, Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Israel
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