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Torres-López M, Spiller PF, Gao L, García-Flores P, Murphy MP, Ortega-Sáenz P, López-Barneo J. Acute oxygen sensing by arterial chemoreceptors with a mutant mitochondrial complex I ND6 subunit lacking reverse electron transport. FEBS Lett 2025; 599:1122-1134. [PMID: 39981615 DOI: 10.1002/1873-3468.70017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2024] [Revised: 01/28/2025] [Accepted: 01/30/2025] [Indexed: 02/22/2025]
Abstract
Carotid body glomus cells are essential for stimulating breathing in response to hypoxia. They contain specialized mitochondria in which hypoxia induces the accumulation of NADH and H2O2 that modulate membrane ion channel activity. We investigated whether hypoxia induces reverse electron transport (RET) at mitochondrial complex I (MCI). We studied glomus cells from mice with a mutation in ND6, a core protein of MCI, which maintain normal MCI NADH dehydrogenase activity but cannot catalyze RET. The ND6 mutation increases the propensity of MCI to deactivate, and glomus cells with deactivated MCI are insensitive to acute hypoxia. These findings further indicate that MCI function is necessary for glomus cell responsiveness to hypoxia, although MCI RET does not seem to be required for this process.
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Affiliation(s)
- María Torres-López
- Institute of Biomedicine of Seville (IBiS), University Hospital 'Virgen del Rocío'/CSIC/University of Seville, Spain
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Spain
- CIBERNED, Madrid, Spain
| | - Pedro F Spiller
- Institute of Biomedicine of Seville (IBiS), University Hospital 'Virgen del Rocío'/CSIC/University of Seville, Spain
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Spain
| | - Lin Gao
- Institute of Biomedicine of Seville (IBiS), University Hospital 'Virgen del Rocío'/CSIC/University of Seville, Spain
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Spain
- CIBERNED, Madrid, Spain
| | - Paula García-Flores
- Institute of Biomedicine of Seville (IBiS), University Hospital 'Virgen del Rocío'/CSIC/University of Seville, Spain
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Spain
- CIBERNED, Madrid, Spain
| | | | - Patricia Ortega-Sáenz
- Institute of Biomedicine of Seville (IBiS), University Hospital 'Virgen del Rocío'/CSIC/University of Seville, Spain
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Spain
- CIBERNED, Madrid, Spain
| | - José López-Barneo
- Institute of Biomedicine of Seville (IBiS), University Hospital 'Virgen del Rocío'/CSIC/University of Seville, Spain
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Spain
- CIBERNED, Madrid, Spain
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Frost S, Pham K, Puvvula N, Oeung B, Heinrich EC. Changes in hypoxic and hypercapnic ventilatory responses at high altitude measured using rebreathing methods. J Appl Physiol (1985) 2024; 137:364-373. [PMID: 38779762 DOI: 10.1152/japplphysiol.00128.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024] Open
Abstract
Ventilatory responses to hypoxia and hypercapnia play a vital role in maintaining gas exchange homeostasis and in adaptation to high-altitude environments. This study investigates the mechanisms underlying sensitization of hypoxic and hypercapnic ventilatory response (HVR and HCVR, respectively) in individuals acclimatized to moderate high altitude (3,800 m). Thirty-one participants underwent chemoreflex testing using the Duffin-modified rebreathing technique. Measures were taken at sea level and after 2 days of acclimatization to high altitude. Ventilatory recruitment threshold (VRT), HCVR-Hyperoxia, HCVR-Hypoxia, and HVR were quantified. Acclimatization to high altitude resulted in increased HVR (P < 0.001) and HCVR-Hyperoxia (P < 0.001), as expected. We also observed that the decrease in VRT under hypoxic test conditions significantly contributed to the elevated HVR at high altitude since the change in VRT across hyperoxic and hypoxic test conditions was greater at high altitudes compared to baseline sea-level tests (P = 0.043). Pre-VRT, or basal, ventilation also increased at high altitudes (P < 0.001), but the change did not differ between oxygen conditions. Taken together, these data suggest that the increase in HVR at high altitude is at least partially driven by a larger decrease in the VRT in hypoxia versus hyperoxia at high altitude compared to sea level. This study highlights the intricacies of respiratory adaptations during acclimatization to moderate high altitude, shedding light on the roles of the VRT, baseline respiratory drive, and two-slope HCVR in this process. These findings contribute to our understanding of how human respiratory control responds to hypoxic and hypercapnic challenges at high altitude.NEW & NOTEWORTHY We report the first measurements of the hypoxic ventilatory response (HVR) after 2 days at high altitude using a CO2 rebreathing technique. We evaluated mechanisms by which the HVR becomes elevated with acclimatization (increased hypercapnic ventilatory response sensitivity in hypoxia, increased baseline respiratory drive in hypoxia, or lower ventilatory recruitment thresholds in hypoxia). For the first time, we report that decreases in the ventilatory recruitment threshold in hypoxia contribute to elevated HVR at high altitude.
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Affiliation(s)
- Shyleen Frost
- Division of Biomedical Sciences, School of MedicineUniversity of California, Riverside, California, United States
| | - Kathy Pham
- Division of Biomedical Sciences, School of MedicineUniversity of California, Riverside, California, United States
| | - Nikhil Puvvula
- Division of Biomedical Sciences, School of MedicineUniversity of California, Riverside, California, United States
| | - Britney Oeung
- Division of Biomedical Sciences, School of MedicineUniversity of California, Riverside, California, United States
| | - Erica C Heinrich
- Division of Biomedical Sciences, School of MedicineUniversity of California, Riverside, California, United States
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Kim E, Park S, Kim S, Choi Y, Cho JH, Kim G. Is altitude a determinant of the health benefits of nature exposure? A systematic review and meta-analysis. Front Public Health 2022; 10:1021618. [PMID: 36504926 PMCID: PMC9732270 DOI: 10.3389/fpubh.2022.1021618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 11/11/2022] [Indexed: 11/27/2022] Open
Abstract
Introduction Nature exposure is a widely accepted option for promoting public health owing to the recent surge of scientific evidence. However, the actual settings to facilitate this initiative is yet to be extensively reviewed. In this systematic review, we have aimed to provide an up-to-date summary of interventional studies investigating the psycho-physiological effects of forests and urban forests, including details on their physical settings, and investigate an effect-modifying role of altitude and summarize data on the magnitude and shape of the association. Methods A keyword search using five electronic academic databases (PubMed, Embase, PsycINFO, Web of Science, and Scopus) was conducted to identify relevant articles published in English from the inception year to the end of February 2022. The methodological quality was evaluated using the ROBINS-I or ROB2 tool, depending on the study design. Meta-regression and random effects model were jointly used to examine the relationship between altitude and health outcomes. Results We included 27 eligible studies and 31 cases extracted from 19 studies were used for the meta-analysis. In the meta-regression, we observed a non-linear association between altitude and psycho-physiological effects. Altitude had a positive quadratic association with anxiety (p < 0.000, adjusted R 2 = 96.79%), depression (p < 0.000, adjusted R 2 = 98.78%), and fatigue (p < 0.000, adjusted R 2 = 64.74%) alleviating effects. Conversely, altitude demonstrated a negative non-linear association with the blood pressure-lowering effect (p = 0.009, adjusted R 2 = 32.83%). Additionally, the thermal index (THI) and illuminance (lx) levels were significantly associated with effect sizes of psychological restoration. Discussion This review provides moderate-certainty evidence for an effect-modifying role of altitude. The meta-regression results suggested the optimal and minimal altitude ranges for psychological restoration and physiological relaxation, respectively. Despite some limitations, the study findings provide a significant basis for utilizing altitude, which is easily accessible and simple, to promote the health benefits of nature-based initiatives. Systematic review registration https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022310894, identifier: CRD42022310894.
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Gao L, Ortega-Sáenz P, Moreno-Domínguez A, López-Barneo J. Mitochondrial Redox Signaling in O 2-Sensing Chemoreceptor Cells. Antioxid Redox Signal 2022; 37:274-289. [PMID: 35044243 DOI: 10.1089/ars.2021.0255] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Significance: Acute responses to hypoxia are essential for the survival of mammals. The carotid body (CB), the main arterial chemoreceptor, contains glomus cells with oxygen (O2)-sensitive K+ channels, which are inhibited during hypoxia to trigger adaptive cardiorespiratory reflexes. Recent Advances: In this review, recent advances in molecular mechanisms of acute O2 sensing in CB glomus cells are discussed, with a special focus on the signaling role of mitochondria through regulating cellular redox status. These advances have been achieved thanks to the use of genetically engineered redox-sensitive green fluorescent protein (roGFP) probes, which allowed us to monitor rapid changes in ROS production in real time in different subcellular compartments during hypoxia. This methodology was used in combination with conditional knockout mice models, pharmacological approaches, and transcriptomic studies. We have proposed a mitochondria-to-membrane signaling model of acute O2 sensing in which H2O2 released in the mitochondrial intermembrane space serves as a signaling molecule to inhibit K+ channels on the plasma membrane. Critical Issues: Changes in mitochondrial reactive oxygen species (ROS) production during acute hypoxia are highly compartmentalized in the submitochondrial regions. The use of redox-sensitive probes targeted to specific compartments is essential to fully understand the role of mitochondrial ROS in acute O2 sensing. Future Directions: Further studies are needed to specify the ROS and to characterize the target(s) of ROS in chemoreceptor cells during acute hypoxia. These data may also contribute to a more complete understanding of the implication of ROS in acute responses to hypoxia in O2-sensing cells in other organs. Antioxid. Redox Signal. 37, 274-289.
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Affiliation(s)
- Lin Gao
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Alejandro Moreno-Domínguez
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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Adaptive cardiorespiratory changes to chronic continuous and intermittent hypoxia. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:103-123. [PMID: 35965023 PMCID: PMC9906984 DOI: 10.1016/b978-0-323-91534-2.00009-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This chapter reviews cardiorespiratory adaptations to chronic hypoxia (CH) experienced at high altitude and cardiorespiratory pathologies elicited by chronic intermittent hypoxia (CIH) occurring with obstructive sleep apnea (OSA). Short-term CH increases breathing (ventilatory acclimatization to hypoxia) and blood pressure (BP) through carotid body (CB) chemo reflex. Hyperplasia of glomus cells, alterations in ion channels, and recruitment of additional excitatory molecules are implicated in the heightened CB chemo reflex by CH. Transcriptional activation of hypoxia-inducible factors (HIF-1 and 2) is a major molecular mechanism underlying respiratory adaptations to short-term CH. High-altitude natives experiencing long-term CH exhibit blunted hypoxic ventilatory response (HVR) and reduced BP due to desensitization of CB response to hypoxia and impaired processing of CB sensory information at the central nervous system. Ventilatory changes evoked by long-term CH are not readily reversed after return to sea level. OSA patients and rodents subjected to CIH exhibit heightened CB chemo reflex, increased hypoxic ventilatory response, and hypertension. Increased generation of reactive oxygen species (ROS) is a major cellular mechanism underlying CIH-induced enhanced CB chemo reflex and the ensuing cardiorespiratory pathologies. ROS generation by CIH is mediated by nontranscriptional, disrupted HIF-1 and HIF-2-dependent transcriptions as well as epigenetic mechanisms.
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Neurotransmitter Modulation of Carotid Body Germinal Niche. Int J Mol Sci 2020; 21:ijms21218231. [PMID: 33153142 PMCID: PMC7662800 DOI: 10.3390/ijms21218231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 10/30/2020] [Accepted: 11/01/2020] [Indexed: 12/25/2022] Open
Abstract
The carotid body (CB), a neural-crest-derived organ and the main arterial chemoreceptor in mammals, is composed of clusters of cells called glomeruli. Each glomerulus contains neuron-like, O2-sensing glomus cells, which are innervated by sensory fibers of the petrosal ganglion and are located in close contact with a dense network of fenestrated capillaries. In response to hypoxia, glomus cells release transmitters to activate afferent fibers impinging on the respiratory and autonomic centers to induce hyperventilation and sympathetic activation. Glomus cells are embraced by interdigitating processes of sustentacular, glia-like, type II cells. The CB has an extraordinary structural plasticity, unusual for a neural tissue, as it can grow several folds its size in subjects exposed to sustained hypoxia (as for example in high altitude dwellers or in patients with cardiopulmonary diseases). CB growth in hypoxia is mainly due to the generation of new glomeruli and blood vessels. In recent years it has been shown that the adult CB contains a collection of quiescent multipotent stem cells, as well as immature progenitors committed to the neurogenic or the angiogenic lineages. Herein, we review the main properties of the different cell types in the CB germinal niche. We also summarize experimental data suggesting that O2-sensitive glomus cells are the master regulators of CB plasticity. Upon exposure to hypoxia, neurotransmitters and neuromodulators released by glomus cells act as paracrine signals that induce proliferation and differentiation of multipotent stem cells and progenitors, thus causing CB hypertrophy and an increased sensory output. Pharmacological modulation of glomus cell activity might constitute a useful clinical tool to fight pathologies associated with exaggerated sympathetic outflow due to CB overactivation.
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Kim LJ, Polotsky VY. Carotid Body and Metabolic Syndrome: Mechanisms and Potential Therapeutic Targets. Int J Mol Sci 2020; 21:E5117. [PMID: 32698380 PMCID: PMC7404212 DOI: 10.3390/ijms21145117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/11/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022] Open
Abstract
The carotid body (CB) is responsible for the peripheral chemoreflex by sensing blood gases and pH. The CB also appears to act as a peripheral sensor of metabolites and hormones, regulating the metabolism. CB malfunction induces aberrant chemosensory responses that culminate in the tonic overactivation of the sympathetic nervous system. The sympatho-excitation evoked by CB may contribute to the pathogenesis of metabolic syndrome, inducing systemic hypertension, insulin resistance and sleep-disordered breathing. Several molecular pathways are involved in the modulation of CB activity, and their pharmacological manipulation may lead to overall benefits for cardiometabolic diseases. In this review, we will discuss the role of the CB in the regulation of metabolism and in the pathogenesis of the metabolic dysfunction induced by CB overactivity. We will also explore the potential pharmacological targets in the CB for the treatment of metabolic syndrome.
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Affiliation(s)
- Lenise J. Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA;
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8
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Abstract
The carotid body (CB) is an arterial chemoreceptor organ located in the carotid bifurcation and has a well-recognized role in cardiorespiratory regulation. The CB contains neurosecretory sensory cells (glomus cells), which release transmitters in response to hypoxia, hypercapnia, and acidemia to activate afferent sensory fibers terminating in the respiratory and autonomic brainstem centers. Knowledge of the physiology of the CB has progressed enormously in recent years. Herein we review advances concerning the organization and function of the cellular elements of the CB, with emphasis on the molecular mechanisms of acute oxygen sensing by glomus cells. We introduce the modern view of the CB as a multimodal integrated metabolic sensor and describe the properties of the CB stem cell niche, which support CB growth during acclimatization to chronic hypoxia. Finally, we discuss the increasing medical relevance of CB dysfunction and its potential impact on the mechanisms of disease.
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Affiliation(s)
- Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla 41013, Spain; , .,Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla 41009, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Sevilla 41013, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla 41013, Spain; , .,Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla 41009, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Sevilla 41013, Spain
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Sobrino V, Annese V, Pardal R. Progenitor Cell Heterogeneity in the Adult Carotid Body Germinal Niche. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1123:19-38. [PMID: 31016593 DOI: 10.1007/978-3-030-11096-3_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Somatic stem cells confer plasticity to adult tissues, permitting their maintenance, repair and adaptation to a changing environment. Adult germinal niches supporting somatic stem cells have been thoroughly characterized throughout the organism, including in central and peripheral nervous systems. Stem cells do not reside alone within their niches, but they are rather accompanied by multiple progenitor cells that not only contribute to the progression of stem cell lineage but also regulate their behavior. Understanding the mechanisms underlying these interactions within the niche is crucial to comprehend associated pathologies and to use stem cells in cell therapy. We have described a stunning germinal niche in the adult peripheral nervous system: the carotid body. This is a chemoreceptor organ with a crucial function during physiological adaptation to hypoxia. We have shown the presence of multipotent stem cells within this niche, escorted by multiple restricted progenitor cell types that contribute to niche physiology and hence organismal adaptation to the lack of oxygen. Herein, we discuss new and existing data about the nature of all these stem and progenitor cell types present in the carotid body germinal niche, discussing their role in physiology and their clinical relevance for the treatment of diverse pathologies.
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Affiliation(s)
- Verónica Sobrino
- Dpto. de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Valentina Annese
- Dpto. de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Ricardo Pardal
- Dpto. de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.
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Jha NK, Jha SK, Sharma R, Kumar D, Ambasta RK, Kumar P. Hypoxia-Induced Signaling Activation in Neurodegenerative Diseases: Targets for New Therapeutic Strategies. J Alzheimers Dis 2018; 62:15-38. [DOI: 10.3233/jad-170589] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Niraj Kumar Jha
- Molecular Neuroscience and Functional Genomics Laboratory, Delhi Technological University (Formerly DCE), Delhi, India
| | - Saurabh Kumar Jha
- Molecular Neuroscience and Functional Genomics Laboratory, Delhi Technological University (Formerly DCE), Delhi, India
| | - Renu Sharma
- Molecular Neuroscience and Functional Genomics Laboratory, Delhi Technological University (Formerly DCE), Delhi, India
| | - Dhiraj Kumar
- Molecular Neuroscience and Functional Genomics Laboratory, Delhi Technological University (Formerly DCE), Delhi, India
| | - Rashmi K. Ambasta
- Molecular Neuroscience and Functional Genomics Laboratory, Delhi Technological University (Formerly DCE), Delhi, India
| | - Pravir Kumar
- Molecular Neuroscience and Functional Genomics Laboratory, Delhi Technological University (Formerly DCE), Delhi, India
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López-Barneo J. Oxygen sensing and stem cell activation in the hypoxic carotid body. Cell Tissue Res 2018; 372:417-425. [PMID: 29368257 DOI: 10.1007/s00441-017-2783-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 12/22/2017] [Indexed: 12/15/2022]
Abstract
The carotid body (CB) is the major arterial chemoreceptor responsible for the detection of acute decreases in O2 tension (hypoxia) in arterial blood that trigger hyperventilation and sympathetic activation. The CB contains O2-sensitive glomus (chief) cells, which respond to hypoxia with the release of transmitters to activate sensory nerve fibers impinging upon the brain respiratory and autonomic centers. During exposure to sustained hypoxia (for weeks or months), the CB grows several-fold in size, a response associated with acclimatization to high altitude or to medical conditions presenting hypoxemia. Here, I briefly present recent advances on the mechanisms underlying glomus cell sensitivity to hypoxia, in particular the role of mitochondrial complex I in acute oxygen sensing. I also summarize the properties of adult CB stem cells and of glomus cell-stem cell synapses, which contribute to CB hypertrophy in chronic hypoxia. A note on the relationship between hypoxic CB growth and tumorigenesis is included. Finally, the medical implications of CB pathophysiology are discussed.
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Affiliation(s)
- José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Avenida Manuel Siurot s/n, 41013, Seville, Spain. .,Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
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12
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Flaherty G, O'Connor R, Johnston N. Altitude training for elite endurance athletes: A review for the travel medicine practitioner. Travel Med Infect Dis 2016; 14:200-11. [PMID: 27040934 DOI: 10.1016/j.tmaid.2016.03.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 11/30/2022]
Abstract
High altitude training is regarded as an integral component of modern athletic preparation, especially for endurance sports such as middle and long distance running. It has rapidly achieved popularity among elite endurance athletes and their coaches. Increased hypoxic stress at altitude facilitates key physiological adaptations within the athlete, which in turn may lead to improvements in sea-level athletic performance. Despite much research in this area to date, the exact mechanisms which underlie such improvements remain to be fully elucidated. This review describes the current understanding of physiological adaptation to high altitude training and its implications for athletic performance. It also discusses the rationale and main effects of different training models currently employed to maximise performance. Athletes who travel to altitude for training purposes are at risk of suffering the detrimental effects of altitude. Altitude illness, weight loss, immune suppression and sleep disturbance may serve to limit athletic performance. This review provides an overview of potential problems which an athlete may experience at altitude, and offers specific training recommendations so that these detrimental effects are minimised.
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Affiliation(s)
- Gerard Flaherty
- School of Medicine, National University of Ireland, Galway, Ireland; School of Medicine, International Medical University, Kuala Lumpur, Malaysia.
| | - Rory O'Connor
- School of Biomedical Science, National University of Ireland, Galway, Ireland.
| | - Niall Johnston
- School of Medicine, National University of Ireland, Galway, Ireland.
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Manuel AR, Hart N, Stradling JR. Correlates of obesity-related chronic ventilatory failure. BMJ Open Respir Res 2016; 3:e000110. [PMID: 26918192 PMCID: PMC4762144 DOI: 10.1136/bmjresp-2015-000110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/08/2015] [Accepted: 12/11/2015] [Indexed: 12/12/2022] Open
Abstract
Introduction Only a third of obese patients develop chronic ventilatory failure. This cross-sectional study assessed multiple factors potentially associated with chronic ventilatory failure. Materials/patients and methods Participants had a body mass index (BMI) >30 kg/m2, with or without chronic ventilatory failure (awake arterial partial pressure of carbon dioxide >6 kPa or base excess (BE) ≥2 mmols/L). Factors investigated were grouped into domains: (1) obesity measures, (2) pulmonary function, (3) respiratory and non-respiratory muscle strength, (4) sleep study derivatives, (5) hypoxic and hypercapnic responses, and (6) some hormonal, nutritional and inflammatory measures. Results 71 obese participants (52% male) were studied over 27 months, 52 (SD 9) years and BMI 47 (range 32–74) kg/m2. The best univariate correlates of BE from each domain were: (1) dual-energy X-ray absorptiometry measurement of visceral fat (r=+0.50, p=0.001); (2) supine forced expiratory volume in 1 s (r=−0.40, p=0.001); (3) sniff maximum pressure (r=−0.28, p=0.02); (4) mean overnight arterial oxygen saturation (r=−0.50, p<0.001); (5) ventilatory response to 15% O2 breathing (r=−0.28, p=0.02); and (6) vitamin D (r=−0.30, p=0.01). In multivariate analysis, only visceral fat and ventilatory response to hypoxia remained significant. Conclusions We have confirmed that in the obese, BMI is a poor correlate of chronic ventilatory failure, and the best independent correlates are visceral fat and hypoxic ventilatory response. Trial registration number NCT01380418.
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Affiliation(s)
- Ari R Manuel
- Oxford Centre for Respiratory Medicine, NIHR Oxford Biomedical Research Centre, Oxford University Churchill Campus, and Oxford University Hospitals NHS Trust , Oxford , UK
| | - Nicholas Hart
- Lane Fox Clinical Respiratory Physiology Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust , London , UK
| | - John R Stradling
- Oxford Centre for Respiratory Medicine, NIHR Oxford Biomedical Research Centre, Oxford University Churchill Campus, and Oxford University Hospitals NHS Trust , Oxford , UK
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14
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Oxygen-sensing by arterial chemoreceptors: Mechanisms and medical translation. Mol Aspects Med 2016; 47-48:90-108. [DOI: 10.1016/j.mam.2015.12.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022]
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López-Barneo J, González-Rodríguez P, Gao L, Fernández-Agüera MC, Pardal R, Ortega-Sáenz P. Oxygen sensing by the carotid body: mechanisms and role in adaptation to hypoxia. Am J Physiol Cell Physiol 2016; 310:C629-42. [PMID: 26764048 DOI: 10.1152/ajpcell.00265.2015] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oxygen (O2) is fundamental for cell and whole-body homeostasis. Our understanding of the adaptive processes that take place in response to a lack of O2(hypoxia) has progressed significantly in recent years. The carotid body (CB) is the main arterial chemoreceptor that mediates the acute cardiorespiratory reflexes (hyperventilation and sympathetic activation) triggered by hypoxia. The CB is composed of clusters of cells (glomeruli) in close contact with blood vessels and nerve fibers. Glomus cells, the O2-sensitive elements in the CB, are neuron-like cells that contain O2-sensitive K(+)channels, which are inhibited by hypoxia. This leads to cell depolarization, Ca(2+)entry, and the release of transmitters to activate sensory fibers terminating at the respiratory center. The mechanism whereby O2modulates K(+)channels has remained elusive, although several appealing hypotheses have been postulated. Recent data suggest that mitochondria complex I signaling to membrane K(+)channels plays a fundamental role in acute O2sensing. CB activation during exposure to low Po2is also necessary for acclimatization to chronic hypoxia. CB growth during sustained hypoxia depends on the activation of a resident population of stem cells, which are also activated by transmitters released from the O2-sensitive glomus cells. These advances should foster further studies on the role of CB dysfunction in the pathogenesis of highly prevalent human diseases.
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Affiliation(s)
- José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Patricia González-Rodríguez
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Lin Gao
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - M Carmen Fernández-Agüera
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Ricardo Pardal
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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16
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Carotid body oxygen sensing and adaptation to hypoxia. Pflugers Arch 2015; 468:59-70. [DOI: 10.1007/s00424-015-1734-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/01/2015] [Accepted: 09/04/2015] [Indexed: 10/23/2022]
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17
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Macías D, Fernández-Agüera MC, Bonilla-Henao V, López-Barneo J. Deletion of the von Hippel-Lindau gene causes sympathoadrenal cell death and impairs chemoreceptor-mediated adaptation to hypoxia. EMBO Mol Med 2015; 6:1577-92. [PMID: 25385837 PMCID: PMC4287976 DOI: 10.15252/emmm.201404153] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mutations of the von Hippel–Lindau (VHL) gene are associated with pheochromocytomas and paragangliomas, but the role of VHL in sympathoadrenal homeostasis is unknown. We generated mice lacking Vhl in catecholaminergic cells. They exhibited atrophy of the carotid body (CB), adrenal medulla, and sympathetic ganglia. Vhl-null animals had an increased number of adult CB stem cells, although the survival of newly generated neuron-like glomus cells was severely compromised. The effects of Vhl deficiency were neither prevented by pharmacological inhibition of prolyl hydroxylases or selective genetic down-regulation of prolyl hydroxylase-3, nor phenocopied by hypoxia inducible factor overexpression. Vhl-deficient animals appeared normal in normoxia but survived for only a few days in hypoxia, presenting with pronounced erythrocytosis, pulmonary edema, and right cardiac hypertrophy. Therefore, in the normal sympathoadrenal setting, Vhl deletion does not give rise to tumors but impairs development and plasticity of the peripheral O2-sensing system required for survival in hypoxic conditions.
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Affiliation(s)
- David Macías
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Mary Carmen Fernández-Agüera
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Victoria Bonilla-Henao
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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18
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Ashley Z, Schwenke DO, Cragg PA. Hyperventilation in normoxia following myocardial infarction in rats: a shift in the set point of the hypoxic ventilatory response. Acta Physiol (Oxf) 2015; 214:415-25. [PMID: 25980319 DOI: 10.1111/apha.12527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 01/22/2015] [Accepted: 05/08/2015] [Indexed: 11/30/2022]
Abstract
AIM The peripheral chemoreflex is augmented in heart failure, and it may contribute to sympathoexcitation. This study aimed to investigate both the chemoreflex and the cardiac sympathetic nerve activity in the acute-stage post-myocardial infarction. METHODS Myocardial infarction was induced in male adult Sprague-Dawley rats by permanent ligation of the left anterior descending coronary artery. Within-animal repeated measure assessment of normoxic and hypoxic ventilation patterns was determined with whole-body plethysmography and compared to sham-operated controls. Cardiac function, morphology and cardiac sympathetic nerve activity were determined 14 days later. RESULTS Infarction induced increases in normoxic ventilation through increases in tidal volume within 3 days. At the same time points, the hypoxic ventilatory response to short durations (10 min) of hypoxia (8, 10 and 12% inspired O2 ) was blunted. At the end of the experiment (D14), increases in nerve activity, specifically through increased firing rate, and significant cardiac dysfunction (ejection fraction 43%) were observed in myocardial infarction (MI) group. CONCLUSIONS An augmentation of normoxic ventilation caused by myocardial infarction occurs before the amplification of the hypoxic ventilatory response. It occurs much earlier following myocardial injury than previously demonstrated and may have a role in initiating cardiac sympathoexcitation. The difference in the augmentation of hypoxic response between early and late stages post-myocardial infarction suggest that the initial change in the chemoreflex is an alteration to the operating point of chemoreflex.
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Affiliation(s)
- Z. Ashley
- Department of Physiology; Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - D. O. Schwenke
- Department of Physiology; Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - P. A. Cragg
- Department of Physiology; Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
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19
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d’Anglemont de Tassigny X, Sirerol-Piquer MS, Gómez-Pinedo U, Pardal R, Bonilla S, Capilla-Gonzalez V, López-López I, De la Torre-Laviana FJ, García-Verdugo JM, López-Barneo J. Resistance of subventricular neural stem cells to chronic hypoxemia despite structural disorganization of the germinal center and impairment of neuronal and oligodendrocyte survival. HYPOXIA (AUCKLAND, N.Z.) 2015; 3:15-33. [PMID: 27774479 PMCID: PMC5045070 DOI: 10.2147/hp.s78248] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Chronic hypoxemia, as evidenced in de-acclimatized high-altitude residents or in patients with chronic obstructive respiratory disorders, is a common medical condition that can produce serious neurological alterations. However, the pathogenesis of this phenomenon is unknown. We have found that adult rodents exposed for several days/weeks to hypoxia, with an arterial oxygen tension similar to that of chronically hypoxemic patients, manifest a partially irreversible structural disarrangement of the subventricular neurogenic niche (subventricular zone) characterized by displacement of neurons and myelinated axons, flattening of the ependymal cell layer, and thinning of capillary walls. Despite these abnormalities, the number of neuronal and oligodendrocyte progenitors, neuroblasts, and neurosphere-forming cells as well as the proliferative activity in subventricular zone was unchanged. These results suggest that neural stem cells and their undifferentiated progeny are resistant to hypoxia. However, in vivo and in vitro experiments indicate that severe chronic hypoxia decreases the survival of newly generated neurons and oligodendrocytes, with damage of myelin sheaths. These findings help explain the effects of hypoxia on adult neurogenesis and provide new perspectives on brain responsiveness to persistent hypoxemia.
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Affiliation(s)
- Xavier d’Anglemont de Tassigny
- Medical Physiology and Biophysics Department, Institute of Biomedicine of Seville (IBiS), Virgen del Rocío University Hospital/CSIC/University of Seville, Seville, Spain
| | - M Salomé Sirerol-Piquer
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain
- Network Center of Biomedical Research on Neurodegenerative Diseases (CIBERNED), Spain
| | - Ulises Gómez-Pinedo
- Laboratory of Regenerative Medicine, San Carlos Institute of Health Investigation, Madrid, Spain
| | - Ricardo Pardal
- Medical Physiology and Biophysics Department, Institute of Biomedicine of Seville (IBiS), Virgen del Rocío University Hospital/CSIC/University of Seville, Seville, Spain
| | - Sonia Bonilla
- Medical Physiology and Biophysics Department, Institute of Biomedicine of Seville (IBiS), Virgen del Rocío University Hospital/CSIC/University of Seville, Seville, Spain
| | - Vivian Capilla-Gonzalez
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain
| | - Ivette López-López
- Medical Physiology and Biophysics Department, Institute of Biomedicine of Seville (IBiS), Virgen del Rocío University Hospital/CSIC/University of Seville, Seville, Spain
| | - Francisco Javier De la Torre-Laviana
- Medical Physiology and Biophysics Department, Institute of Biomedicine of Seville (IBiS), Virgen del Rocío University Hospital/CSIC/University of Seville, Seville, Spain
| | - José Manuel García-Verdugo
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain
- Network Center of Biomedical Research on Neurodegenerative Diseases (CIBERNED), Spain
| | - José López-Barneo
- Medical Physiology and Biophysics Department, Institute of Biomedicine of Seville (IBiS), Virgen del Rocío University Hospital/CSIC/University of Seville, Seville, Spain
- Network Center of Biomedical Research on Neurodegenerative Diseases (CIBERNED), Spain
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20
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Jochmans-Lemoine A, Villalpando G, Gonzales M, Valverde I, Soria R, Joseph V. Divergent physiological responses in laboratory rats and mice raised at high altitude. J Exp Biol 2015; 218:1035-1043. [DOI: 10.1242/jeb.112862] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
ABSTRACTEcological studies show that mice can be found at high altitude (HA – up to 4000 m) while rats are absent at these altitudes, and there are no data to explain this discrepancy. We used adult laboratory rats and mice that have been raised for more than 30 generations in La Paz, Bolivia (3600 m), and compared their hematocrit levels, right ventricular hypertrophy (index of pulmonary hypertension) and alveolar surface area in the lungs. We also used whole-body plethysmography, indirect calorimetry and pulse oxymetry to measure ventilation, metabolic rate (O2 consumption and CO2 production), heart rate and pulse oxymetry oxygen saturation (pO2,sat) under ambient conditions, and in response to exposure to sea level PO2 (32% O2=160 mmHg for 10 min) and hypoxia (18% and 15% O2=90 and 75 mmHg for 10 min each). The variables used for comparisons between species were corrected for body mass using standard allometric equations, and are termed mass-corrected variables. Under baseline, compared with rats, adult mice had similar levels of pO2,sat, but lower hematocrit and hemoglobin levels, reduced right ventricular hypertrophy and higher mass-corrected alveolar surface area, tidal volume and metabolic rate. In response to sea level PO2 and hypoxia, mice and rats had similar changes of ventilation, but metabolic rate decreased much more in hypoxia in mice, while pO2,sat remained higher in mice. We conclude that laboratory mice and rats that have been raised at HA for >30 generations have different physiological responses to altitude. These differences might explain the different altitude distribution observed in wild rats and mice.
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Affiliation(s)
| | - Gabriella Villalpando
- Instituto Boliviano de Biologia de Altura, and Universidad Mayor de San Andrés, La Paz, Bolivia
| | - Marcelino Gonzales
- Instituto Boliviano de Biologia de Altura, and Universidad Mayor de San Andrés, La Paz, Bolivia
| | - Ibana Valverde
- Instituto Boliviano de Biologia de Altura, and Universidad Mayor de San Andrés, La Paz, Bolivia
| | - Rudy Soria
- Instituto Boliviano de Biologia de Altura, and Universidad Mayor de San Andrés, La Paz, Bolivia
| | - Vincent Joseph
- Centre de Recherche du CHU de Québec, and Université Laval, Quebec, Quebec, Canada G1L3L5
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21
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Johnson SM, Krisp AR, Bartman ME. Hypoxia switches episodic breathing to singlet breathing in red-eared slider turtles (Trachemys scripta) via a tropisetron-sensitive mechanism. Respir Physiol Neurobiol 2014; 207:48-57. [PMID: 25543027 DOI: 10.1016/j.resp.2014.12.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 11/05/2014] [Accepted: 11/05/2014] [Indexed: 10/24/2022]
Abstract
Hypoxia-induced changes in the chelonian breathing pattern are poorly understood. Thus, breathing was measured in freely swimming adult red-eared slider turtles breathing air prior to breathing nitrogen for 4h. Ventilation increased 10-fold within 10min due to increased breath frequency and tidal volume. Breaths/episode decreased by ∼50% within after 1h of hypoxia while the number of singlet breaths increased from 3.1±1.6singlets/h to a maximum of 66.1±23.5singlets/h. Expiratory and inspiratory duration increased during hypoxia. For doublet and triplet breaths, expiratory duration increased during the first breath only, while inspiratory duration increased for all breaths. Tropisetron (5-HT3 receptor antagonist, 5mg/kg) administration prior to hypoxia attenuated the hypoxia-induced increase in singlet breath frequency. Along with results from previous in vitro studies, this study suggests that 5-HT3 receptor activation may be required for the hypoxia-induced increase in singlet breathing pattern in red-eared slider turtles.
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Affiliation(s)
- Stephen M Johnson
- Department of Comparative Biosciences, School of Veterinary Medicine University of Wisconsin, Madison, WI 53706, USA.
| | - Ashley R Krisp
- Department of Comparative Biosciences, School of Veterinary Medicine University of Wisconsin, Madison, WI 53706, USA
| | - Michelle E Bartman
- Department of Comparative Biosciences, School of Veterinary Medicine University of Wisconsin, Madison, WI 53706, USA
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22
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Samillan V, Haider T, Vogel J, Leuenberger C, Brock M, Schwarzwald C, Gassmann M, Ostergaard L. Combination of erythropoietin and sildenafil can effectively attenuate hypoxia-induced pulmonary hypertension in mice. Pulm Circ 2014; 3:898-907. [PMID: 25006406 DOI: 10.1086/674758] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 08/22/2013] [Indexed: 12/12/2022] Open
Abstract
Pulmonary hypertension (PH) is an incurable disease that often leads to right ventricular hypertrophy and right heart failure. This study investigated single versus combined therapy with sildenafil and erythropoietin on hypoxia-induced pulmonary hypertension in mice. Mice were randomized into 5 groups and exposed to either hypoxia (10% oxygen) or normoxia for a total of 5 weeks. Hypoxic mice were treated with saline solution, erythropoietin (500 IU/kg 3 times weekly), sildenafil (10 mg/kg daily), or a combination of the two drugs for the last 2 weeks of hypoxic exposure. We measured right ventricular pressures using right heart catheterization, and the ventilatory response to hypoxia was recorded via whole-body plethysmography. Histological analyses were performed to elucidate changes in pulmonary morphology and appearance of right heart hypertrophy. Plasma levels of cardiotrophin-1 and atrial natriuretic peptide were quantified. Treatment with either erythropoietin or sildenafil alone lowered the hypoxia-induced increase of pulmonary pressure and reduced pulmonary edema formation, pulmonary vascular remodeling, and right ventricular hypertrophy. Notably, the combination of the two drugs had the most prominent effect. Changes in cardiotrophin-1 and atrial natriuretic protein levels confirmed these observations. The combination treatment with erythropoietin and sildenafil demonstrated an attenuation of the development of hypoxia-induced PH in mice that was superior to that observed for either drug when given alone.
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Affiliation(s)
- Victor Samillan
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland ; Human Physiology Department, Medical School, Universidad Alas Peruanas, Lima, Peru
| | - Thomas Haider
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland
| | - Johannes Vogel
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland
| | - Caroline Leuenberger
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, Switzerland
| | - Matthias Brock
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Division of Pulmonology, University Hospital Zurich, Zurich, Switzerland
| | - Colin Schwarzwald
- Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Max Gassmann
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland ; Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Louise Ostergaard
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland
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23
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Platero-Luengo A, González-Granero S, Durán R, Díaz-Castro B, Piruat JI, García-Verdugo JM, Pardal R, López-Barneo J. An O2-sensitive glomus cell-stem cell synapse induces carotid body growth in chronic hypoxia. Cell 2014; 156:291-303. [PMID: 24439383 DOI: 10.1016/j.cell.2013.12.013] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 10/07/2013] [Accepted: 11/11/2013] [Indexed: 01/28/2023]
Abstract
Neural stem cells (NSCs) exist in germinal centers of the adult brain and in the carotid body (CB), an oxygen-sensing organ that grows under chronic hypoxemia. How stem cell lineage differentiation into mature glomus cells is coupled with changes in physiological demand is poorly understood. Here, we show that hypoxia does not affect CB NSC proliferation directly. Rather, mature glomus cells expressing endothelin-1, the O2-sensing elements in the CB that secrete neurotransmitters in response to hypoxia, establish abundant synaptic-like contacts with stem cells, which express endothelin receptors, and instruct their growth. Inhibition of glomus cell transmitter release or their selective destruction markedly diminishes CB cell growth during hypoxia, showing that CB NSCs are under the direct "synaptic" control of the mature O2-sensitive cells. Thus, glomus cells not only acutely activate the respiratory center but also induce NSC-dependent CB hypertrophy necessary for acclimatization to chronic hypoxemia.
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Affiliation(s)
- Aida Platero-Luengo
- Departamento de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain
| | - Susana González-Granero
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universidad de Valencia, 46071 Valencia, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Rocío Durán
- Departamento de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain
| | - Blanca Díaz-Castro
- Departamento de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain
| | - José I Piruat
- Departamento de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain
| | - José Manuel García-Verdugo
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universidad de Valencia, 46071 Valencia, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Ricardo Pardal
- Departamento de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain.
| | - José López-Barneo
- Departamento de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain.
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24
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Willie CK, Tzeng YC, Fisher JA, Ainslie PN. Integrative regulation of human brain blood flow. J Physiol 2014; 592:841-59. [PMID: 24396059 PMCID: PMC3948549 DOI: 10.1113/jphysiol.2013.268953] [Citation(s) in RCA: 622] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/24/2013] [Indexed: 02/06/2023] Open
Abstract
Herein, we review mechanisms regulating cerebral blood flow (CBF), with specific focus on humans. We revisit important concepts from the older literature and describe the interaction of various mechanisms of cerebrovascular control. We amalgamate this broad scope of information into a brief review, rather than detailing any one mechanism or area of research. The relationship between regulatory mechanisms is emphasized, but the following three broad categories of control are explicated: (1) the effect of blood gases and neuronal metabolism on CBF; (2) buffering of CBF with changes in blood pressure, termed cerebral autoregulation; and (3) the role of the autonomic nervous system in CBF regulation. With respect to these control mechanisms, we provide evidence against several canonized paradigms of CBF control. Specifically, we corroborate the following four key theses: (1) that cerebral autoregulation does not maintain constant perfusion through a mean arterial pressure range of 60-150 mmHg; (2) that there is important stimulatory synergism and regulatory interdependence of arterial blood gases and blood pressure on CBF regulation; (3) that cerebral autoregulation and cerebrovascular sensitivity to changes in arterial blood gases are not modulated solely at the pial arterioles; and (4) that neurogenic control of the cerebral vasculature is an important player in autoregulatory function and, crucially, acts to buffer surges in perfusion pressure. Finally, we summarize the state of our knowledge with respect to these areas, outline important gaps in the literature and suggest avenues for future research.
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Affiliation(s)
- Christopher K Willie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada V1V 1V7.
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25
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Abstract
This paper describes the interactions between ventilation and acid-base balance under a variety of conditions including rest, exercise, altitude, pregnancy, and various muscle, respiratory, cardiac, and renal pathologies. We introduce the physicochemical approach to assessing acid-base status and demonstrate how this approach can be used to quantify the origins of acid-base disorders using examples from the literature. The relationships between chemoreceptor and metaboreceptor control of ventilation and acid-base balance summarized here for adults, youth, and in various pathological conditions. There is a dynamic interplay between disturbances in acid-base balance, that is, exercise, that affect ventilation as well as imposed or pathological disturbances of ventilation that affect acid-base balance. Interactions between ventilation and acid-base balance are highlighted for moderate- to high-intensity exercise, altitude, induced acidosis and alkalosis, pregnancy, obesity, and some pathological conditions. In many situations, complete acid-base data are lacking, indicating a need for further research aimed at elucidating mechanistic bases for relationships between alterations in acid-base state and the ventilatory responses.
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Affiliation(s)
- Michael I Lindinger
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
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26
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Burg CJ, Montgomery-Downs HE, Mettler P, Gozal D, Halbower AC. Respiratory and polysomnographic values in 3- to 5-year-old normal children at higher altitude. Sleep 2013; 36:1707-14. [PMID: 24179305 DOI: 10.5665/sleep.3134] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES To determine polysomnographic parameter differences in children living at higher altitude to children living near sea level. DESIGN AND SETTING Prospective study of non-snoring, normal children recruited from various communities around Denver, CO. In-lab, overnight polysomnograms were performed at a tertiary care children's hospital. All children required residence for greater than one year at an elevation around 1,600 meters. PARTICIPANTS 45 children (62% female), aged 3-5 years, 88.9% non-Hispanic white with average BMI percentile for age of 47.8% ± 30.7%. MEASUREMENTS AND RESULTS Standard sleep indices were obtained and compared to previously published normative values in a similar population living near sea level (SLG). In the altitude group (AG), the apnea-hypopnea index was 1.8 ± 1.2 and the central apnea-hypopnea index was 1.7 ± 1.1, as compared to 0.9 ± 0.8 and 0.8 ± 0.7, respectively, (P ≤ 0.005) in SLG. Mean end-tidal CO2 level in AG was 42.3 ± 3.0 mm Hg and 40.6 ± 4.6 mm Hg in SLG (P = 0.049). The ≥ 4% desaturation index was 3.9 ± 2.0 in AG compared to 0.3 ± 0.4 in SLG (P < 0.001). Mean periodic limb movement in series index was 10.1 ± 12.3 in AG and 3.6 ± 5.4 in SLG (P = 0.001). CONCLUSION Comparison of altitude and sea level sleep studies in healthy children reveals significant differences in central apnea, apneahypopnea, desaturation, and periodic limb movement in series indices. Clinical providers should be aware of these differences when interpreting sleep studies and incorporate altitude-adjusted normative values in therapeutic-decision making algorithms.
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Affiliation(s)
- Casey J Burg
- University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, CO
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Ainslie PN, Lucas SJ, Burgess KR. Breathing and sleep at high altitude. Respir Physiol Neurobiol 2013; 188:233-56. [DOI: 10.1016/j.resp.2013.05.020] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 05/04/2013] [Accepted: 05/16/2013] [Indexed: 10/26/2022]
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Andrews G, Ainslie PN, Shepherd K, Dawson A, Swart M, Lucas S, Burgess KR. The effect of partial acclimatization to high altitude on loop gain and central sleep apnoea severity. Respirology 2013; 17:835-40. [PMID: 22429599 DOI: 10.1111/j.1440-1843.2012.02170.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND OBJECTIVE Loop gain is an engineering term that predicts the stability of a feedback control system, such as the control of breathing. Based on earlier studies at lower altitudes, it was hypothesized that acclimatization to high altitude would lead to a reduction in loop gain and thus central sleep apnoea (CSA) severity. METHODS This study used exposure to very high altitude to induce CSA in healthy subjects to investigate the effect of partial acclimatization on loop gain and CSA severity. Measurements were made on 12 subjects (age 30 ± 10 years, body mass index 22.8 ± 1.9, eight males, four females) at an altitude of 5050 m over a 2-week period upon initial arrival (days 2-4) and following partial acclimatization (days 12-14). Sleep was studied by full polysomnography, and resting arterial blood gases were measured. Loop gain was measured by the 'duty cycle' method (duration of hyperpnoea/cycle length). RESULTS Partial acclimatization to high-altitude exposure was associated with both an increase in loop gain (duty cycle fell from 0.60 ± 0.05 to 0.55 ± 0.06 (P = 0.03)) and severity of CSA (apnoea-hypopnoea index increased from 76.8 ± 48.8 to 115.9 ± 20.2 (P = 0.01)), while partial arterial carbon dioxide concentration fell from 29 ± 3 to 26 ± 2 (P = 0.01). CONCLUSIONS Contrary to the results at lower altitudes, at high-altitude loop gain and severity of CSA increased.
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Affiliation(s)
- Gareth Andrews
- Department of Medicine, University of Sydney, Sydney, New South Wales, Australia
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Soliz J. Erythropoietin and respiratory control at adulthood and during early postnatal life. Respir Physiol Neurobiol 2013; 185:87-93. [DOI: 10.1016/j.resp.2012.07.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 07/19/2012] [Accepted: 07/20/2012] [Indexed: 01/10/2023]
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Are cardiorespiratory complications a question of epigenetics? Proc Natl Acad Sci U S A 2012; 109:2192-3. [PMID: 22308480 DOI: 10.1073/pnas.1121364109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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The Impact of 32 Days' Exposure to Hypobaric Hypoxia on Physiological Cost of Sub-Maximal Work Performed at the Sea Level. BALTIC JOURNAL OF HEALTH AND PHYSICAL ACTIVITY 2011. [DOI: 10.2478/v10131-011-0002-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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