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Simpson LL, Stembridge M, Siebenmann C, Moore JP, Lawley JS. Mechanisms underpinning sympathoexcitation in hypoxia. J Physiol 2024. [PMID: 38533641 DOI: 10.1113/jp284579] [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: 11/06/2023] [Accepted: 02/28/2024] [Indexed: 03/28/2024] Open
Abstract
Sympathoexcitation is a hallmark of hypoxic exposure, occurring acutely, as well as persisting in acclimatised lowland populations and with generational exposure in highland native populations of the Andean and Tibetan plateaus. The mechanisms mediating altitude sympathoexcitation are multifactorial, involving alterations in both peripheral autonomic reflexes and central neural pathways, and are dependent on the duration of exposure. Initially, hypoxia-induced sympathoexcitation appears to be an adaptive response, primarily mediated by regulatory reflex mechanisms concerned with preserving systemic and cerebral tissue O2 delivery and maintaining arterial blood pressure. However, as exposure continues, sympathoexcitation is further augmented above that observed with acute exposure, despite acclimatisation processes that restore arterial oxygen content (C a O 2 ${C_{{\mathrm{a}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ). Under these conditions, sympathoexcitation may become maladaptive, giving rise to reduced vascular reactivity and mildly elevated blood pressure. Importantly, current evidence indicates the peripheral chemoreflex does not play a significant role in the augmentation of sympathoexcitation during altitude acclimatisation, although methodological limitations may underestimate its true contribution. Instead, processes that provide no obvious survival benefit in hypoxia appear to contribute, including elevated pulmonary arterial pressure. Nocturnal periodic breathing is also a potential mechanism contributing to altitude sympathoexcitation, although experimental studies are required. Despite recent advancements within the field, several areas remain unexplored, including the mechanisms responsible for the apparent normalisation of muscle sympathetic nerve activity during intermediate hypoxic exposures, the mechanisms accounting for persistent sympathoexcitation following descent from altitude and consideration of whether there are sex-based differences in sympathetic regulation at altitude.
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Affiliation(s)
- Lydia L Simpson
- Department of Sport Science, Performance Physiology and Prevention, Universität Innsbruck, Innsbruck, Austria
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | | | - Jonathan P Moore
- School of Psychology and Sport Science, Institute of Applied Human Physiology, Bangor University, Bangor, UK
| | - Justin S Lawley
- Department of Sport Science, Performance Physiology and Prevention, Universität Innsbruck, Innsbruck, Austria
- Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, Italy
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2
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Souza JR, Machado BH. Cardiovascular and respiratory evaluation in adenosine A 2A receptor knockout mice submitted to short-term sustained hypoxia. Exp Physiol 2023; 108:1434-1445. [PMID: 37632713 PMCID: PMC10988442 DOI: 10.1113/ep091221] [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: 03/17/2023] [Accepted: 08/03/2023] [Indexed: 08/28/2023]
Abstract
Sustained hypoxia (SH) in mice induces changes in the respiratory pattern and increase in the parasympathetic tone to the heart. Among adenosine G-protein-coupled receptors (GPCRs), the A2A receptors are especially important in mediating adenosine actions during hypoxia due to their expression in neurons involved with the generation and modulation of the autonomic and respiratory functions. Herein, we performed an in vivo evaluation of the baseline cardiovascular and respiratory parameters and their changes in response to SH in knockout mice for A2A receptors (A2A KO). SH produced similar and significant reductions in mean arterial pressure and heart rate in both wild-type (WT) and A2A KO mice when compared to their respective normoxic controls. Mice from WT and A2A KO groups submitted to normoxia or SH presented similar cardiovascular responses to peripheral chemoreflex activation (KCN). Under normoxic conditions A2A KO mice presented a respiratory frequency (fR ) significantly higher in relation to the WT group, which was reduced in response to SH. These data show that the lack of adenosine A2A receptors in mice does not affect the cardiovascular parameters and the autonomic responses to chemoreflex activation in control (normoxia) and SH mice. We conclude that the A2A receptors play a major role in the control of respiratory frequency and in the tachypnoeic response to SH in mice. NEW FINDINGS: What is the central question of this study? Are cardiovascular and respiratory parameters and their changes in response to sustained hypoxia (SH) altered in adenosine A2A receptor knockout mice? What is the main finding and its importance? Cardiovascular parameters and their changes in response to SH were not altered in A2A KO mice. The respiratory frequency in A2A KO was higher than in WT mice. In response to SH the respiratory frequency increased in WT, while it was reduced in A2A KO mice. A2A receptors play a major role in the modulation of respiratory frequency and in the tachypnoeic response to SH in mice.
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Affiliation(s)
- Juliana R. Souza
- Department of Physiology, School of Medicine of Ribeirão PretoUniversity of São PauloRibeirão PretoSPBrazil
| | - Benedito H. Machado
- Department of Physiology, School of Medicine of Ribeirão PretoUniversity of São PauloRibeirão PretoSPBrazil
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3
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Dempsey JA, Welch JF. Control of Breathing. Semin Respir Crit Care Med 2023; 44:627-649. [PMID: 37494141 DOI: 10.1055/s-0043-1770342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Substantial advances have been made recently into the discovery of fundamental mechanisms underlying the neural control of breathing and even some inroads into translating these findings to treating breathing disorders. Here, we review several of these advances, starting with an appreciation of the importance of V̇A:V̇CO2:PaCO2 relationships, then summarizing our current understanding of the mechanisms and neural pathways for central rhythm generation, chemoreception, exercise hyperpnea, plasticity, and sleep-state effects on ventilatory control. We apply these fundamental principles to consider the pathophysiology of ventilatory control attending hypersensitized chemoreception in select cardiorespiratory diseases, the pathogenesis of sleep-disordered breathing, and the exertional hyperventilation and dyspnea associated with aging and chronic diseases. These examples underscore the critical importance that many ventilatory control issues play in disease pathogenesis, diagnosis, and treatment.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin, Madison, Wisconsin
| | - Joseph F Welch
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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4
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Aldossary HS, Nieves DJ, Kavanagh DM, Owen D, Ray CJ, Kumar P, Coney AM, Holmes AP. Analyzing Angiotensin II Receptor Type 1 Clustering in PC12 Cells in Response to Hypoxia Using Direct Stochastic Optical Reconstruction Microscopy (dSTORM). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1427:175-184. [PMID: 37322348 DOI: 10.1007/978-3-031-32371-3_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Angiotensin II (Ang II) is a hormone that plays a major role in maintaining homeostasis. The Ang II receptor type 1 (AT1R) is expressed in acute O2 sensitive cells, including carotid body (CB) type I cells and pheochromocytoma 12 (PC12) cells, and Ang II increases cell activity. While a functional role for Ang II and AT1Rs in increasing the activity of O2 sensitive cells has been established, the nanoscale distribution of AT1Rs has not. Furthermore, it is not known how exposure to hypoxia may alter the single-molecule arrangement and clustering of AT1Rs. In this study, the AT1R nanoscale distribution under control normoxic conditions in PC12 cells was determined using direct stochastic optical reconstruction microscopy (dSTORM). AT1Rs were arranged in distinct clusters with measurable parameters. Across the entire cell surface there averaged approximately 3 AT1R clusters/μm2 of cell membrane. Cluster area varied in size ranging from 1.1 × 10-4 to 3.9 × 10-2 μm2. Twenty-four hours of exposure to hypoxia (1% O2) altered clustering of AT1Rs, with notable increases in the maximum cluster area, suggestive of an increase in supercluster formation. These observations could aid in understanding mechanisms underlying augmented Ang II sensitivity in O2 sensitive cells in response to sustained hypoxia.
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Affiliation(s)
- Hayyaf S Aldossary
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK.
- College of Medicine, Basic Medical Sciences, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.
| | - Daniel J Nieves
- Institute of Immunology and Immunotherapy and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
| | | | - Dylan Owen
- School of Mathematics, University of Birmingham, Birmingham, UK
| | - Clare J Ray
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Prem Kumar
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Andrew M Coney
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Andrew P Holmes
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK.
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5
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Cates VC, Bruce CD, Marullo AL, Isakovich R, Saran G, Leacy JK, O′Halloran KD, Brutsaert TD, Sherpa MT, Day TA. Steady-state chemoreflex drive captures ventilatory acclimatization during incremental ascent to high altitude: Effect of acetazolamide. Physiol Rep 2022; 10:e15521. [PMID: 36461658 PMCID: PMC9718940 DOI: 10.14814/phy2.15521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 11/03/2022] [Indexed: 06/17/2023] Open
Abstract
Ventilatory acclimatization (VA) is important to maintain adequate oxygenation with ascent to high altitude (HA). Transient hypoxic ventilatory response tests lack feasibility and fail to capture the integrated steady-state responses to chronic hypoxic exposure in HA fieldwork. We recently characterized a novel index of steady-state respiratory chemoreflex drive (SSCD), accounting for integrated contributions from central and peripheral respiratory chemoreceptors during steady-state breathing at prevailing chemostimuli. Acetazolamide is often utilized during ascent for prevention or treatment of altitude-related illnesses, eliciting metabolic acidosis and stimulating respiratory chemoreceptors. To determine if SSCD reflects VA during ascent to HA, we characterized SSCD in 25 lowlanders during incremental ascent to 4240 m over 7 days. We subsequently compared two separate subgroups: no acetazolamide (NAz; n = 14) and those taking an oral prophylactic dose of acetazolamide (Az; 125 mg BID; n = 11). At 1130/1400 m (day zero) and 4240 m (day seven), steady-state measurements of resting ventilation (V̇I ; L/min), pressure of end-tidal (PET )CO2 (Torr), and peripheral oxygen saturation (SpO2 ; %) were measured. A stimulus index (SI; PET CO2 /SpO2 ) was calculated, and SSCD was calculated by indexing V̇I against SI. We found that (a) both V̇I and SSCD increased with ascent to 4240 m (day seven; V̇I : +39%, p < 0.0001, Hedges' g = 1.52; SSCD: +56.%, p < 0.0001, Hedges' g = 1.65), (b) and these responses were larger in the Az versus NAz subgroup (V̇I : p = 0.02, Hedges' g = 1.04; SSCD: p = 0.02, Hedges' g = 1.05). The SSCD metric may have utility in assessing VA during prolonged stays at altitude, providing a feasible alternative to transient chemoreflex tests.
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Affiliation(s)
- Valerie C. Cates
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Christina D. Bruce
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Anthony L. Marullo
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
- Department of Physiology. School of MedicineUniversity Cork CollegeCorkIreland
| | - Rodion Isakovich
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Gurkarn Saran
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Jack K. Leacy
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
- Department of Physiology. School of MedicineUniversity Cork CollegeCorkIreland
| | - Ken D. O′Halloran
- Department of Physiology. School of MedicineUniversity Cork CollegeCorkIreland
| | | | | | - Trevor A. Day
- Department of Biology, Faculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
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6
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Maletz SN, Reid BT, Varga AG, Levitt ES. Nucleus Tractus Solitarius Neurons Activated by Hypercapnia and Hypoxia Lack Mu Opioid Receptor Expression. Front Mol Neurosci 2022; 15:932189. [PMID: 35898697 PMCID: PMC9309891 DOI: 10.3389/fnmol.2022.932189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/14/2022] [Indexed: 11/30/2022] Open
Abstract
Impaired chemoreflex responses are a central feature of opioid-induced respiratory depression, however, the mechanism through which mu opioid receptor agonists lead to diminished chemoreflexes is not fully understood. One brainstem structure involved in opioid-induced impairment of chemoreflexes is the nucleus of the solitary tract (NTS), which contains a population of neurons that express mu opioid receptors. Here, we tested whether caudal NTS neurons activated during the chemoreflex challenge express mu opioid receptors and overlap with neurons activated by opioids. Using genetic labeling of mu opioid receptor-expressing neurons and cFos immunohistochemistry as a proxy for neuronal activation, we examined the distribution of activated NTS neurons following hypercapnia, hypoxia, and morphine administration. The main finding was that hypoxia and hypercapnia primarily activated NTS neurons that did not express mu opioid receptors. Furthermore, concurrent administration of morphine with hypercapnia induced cFos expression in non-overlapping populations of neurons. Together these results suggest an indirect effect of opioids within the NTS, which could be mediated through mu opioid receptors on afferents and/or inhibitory interneurons.
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Affiliation(s)
- Sebastian N. Maletz
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
| | - Brandon T. Reid
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
| | - Adrienn G. Varga
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States
| | - Erica S. Levitt
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States
- *Correspondence: Erica S. Levitt ; orcid.org/0000-0002-3634-6594
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Caravagna C, Casciato A, Coq JO, Liabeuf S, Brocard C, Peyronnet J, Bodineau L, Cayetanot F. Prenatal Hypoxia Induces Cl– Cotransporters KCC2 and NKCC1 Developmental Abnormality and Disturbs the Influence of GABAA and Glycine Receptors on Fictive Breathing in a Newborn Rat. Front Physiol 2022; 13:786714. [PMID: 35250609 PMCID: PMC8890663 DOI: 10.3389/fphys.2022.786714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/17/2022] [Indexed: 11/13/2022] Open
Abstract
Prenatal hypoxia is a recognised risk factor for neurodevelopmental disorders associated with both membrane proteins involved in neuron homeostasis, e.g., chloride (Cl–) cotransporters, and alterations in brain neurotransmitter systems, e.g., catecholamines, dopamine, and GABA. Our study aimed to determine whether prenatal hypoxia alters central respiratory drive by disrupting the development of Cl– cotransporters KCC2 and NKCC1. Cl– homeostasis seems critical for the strength and efficiency of inhibition mediated by GABAA and glycine receptors within the respiratory network, and we searched for alterations of GABAergic and glycinergic respiratory influences after prenatal hypoxia. We measured fictive breathing from brainstem in ex vivo preparations during pharmacological blockade of KCC2 and NKCC1 Cl– cotransporters, GABAA, and glycine receptors. We also evaluated the membrane expression of Cl– cotransporters in the brainstem by Western blot and the expression of Cl– cotransporter regulators brain-derived neurotrophic factor (BDNF) and calpain. First, pharmacological experiments showed that prenatal hypoxia altered the regulation of fictive breathing by NKCC1 and KCC2 Cl– cotransporters, GABA/GABAA, and glycin. NKCC1 inhibition decreased fictive breathing at birth in control mice while it decreased at 4 days after birth in pups exposed to prenatal hypoxia. On the other hand, inhibition of KCC2 decreased fictive breathing 4 days after birth in control mice without any change in prenatal hypoxia pups. The GABAergic system appeared to be more effective in prenatal hypoxic pups whereas the glycinergic system increased its effectiveness later. Second, we observed a decrease in the expression of the Cl– cotransporter KCC2, and a decrease with age in NKCC1, as well as an increase in the expression of BDNF and calpain after prenatal hypoxia exposure. Altogether, our data support the idea that prenatal hypoxia alters the functioning of GABAA and glycinergic systems in the respiratory network by disrupting maturation of Cl– homeostasis, thereby contributing to long-term effects by disrupting ventilation.
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Affiliation(s)
- Céline Caravagna
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children’s Hospital, and Harvard Medical School, Boston, MA, United States
| | - Alexis Casciato
- Sorbonne Université, Inserm UMR_S1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Faculté de Médecine Site Pitié-Salpétrière, Paris, France
| | - Jacques-Olivier Coq
- Institut de Neurosciences de la Timone, UMR 7289, CNRS, Aix-Marseille Université, Marseille, France
| | - Sylvie Liabeuf
- Institut de Neurosciences de la Timone, UMR 7289, CNRS, Aix-Marseille Université, Marseille, France
| | - Cécile Brocard
- Institut de Neurosciences de la Timone, UMR 7289, CNRS, Aix-Marseille Université, Marseille, France
| | - Julie Peyronnet
- Institut de Neurosciences de la Timone, UMR 7289, CNRS, Aix-Marseille Université, Marseille, France
| | - Laurence Bodineau
- Sorbonne Université, Inserm UMR_S1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Faculté de Médecine Site Pitié-Salpétrière, Paris, France
| | - Florence Cayetanot
- Sorbonne Université, Inserm UMR_S1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Faculté de Médecine Site Pitié-Salpétrière, Paris, France
- *Correspondence: Florence Cayetanot,
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8
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Okan A, Doğanyiğit Z, Eroğlu E, Akyüz E, Demir N. Immunoreactive definition of TNF- α, HIF-1 α, Kir6.2, Kir3.1 and M2 muscarinic receptor for cardiac and pancreatic tissues in a mouse model for type 1 diabetes. Life Sci 2021; 284:119886. [PMID: 34389402 DOI: 10.1016/j.lfs.2021.119886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 11/25/2022]
Affiliation(s)
- Aslı Okan
- Department of Histology and Embryology, School of Medicine, Yozgat Bozok University, Yozgat 66100, Turkey
| | - Züleyha Doğanyiğit
- Department of Histology and Embryology, School of Medicine, Yozgat Bozok University, Yozgat 66100, Turkey
| | - Ece Eroğlu
- School of Medicine, Yozgat Bozok University, Yozgat 66100, Turkey
| | - Enes Akyüz
- Department of Biophysics, School of International Medicine, University of Health Sciences, Istanbul 34668, Turkey
| | - Necdet Demir
- Department of Histology and Embryology, School of Medicine, Akdeniz University, Antalya 07070, Turkey.
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9
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Kim LJ, Shin MK, Pho H, Otvos L, Tufik S, Andersen ML, Pham LV, Polotsky VY. Leptin Receptor Blockade Attenuates Hypertension, but Does Not Affect Ventilatory Response to Hypoxia in a Model of Polygenic Obesity. Front Physiol 2021; 12:688375. [PMID: 34276408 PMCID: PMC8283021 DOI: 10.3389/fphys.2021.688375] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/15/2021] [Indexed: 12/24/2022] Open
Abstract
Background Obesity can cause hypertension and exacerbates sleep-disordered breathing (SDB). Leptin is an adipocyte-produced hormone, which increases metabolic rate, suppresses appetite, modulates control of breathing, and increases blood pressure. Obese individuals with high circulating levels of leptin are resistant to metabolic and respiratory effects of leptin, but they appear to be sensitive to hypertensive effects of this hormone. Obesity-induced hypertension has been associated with hyperleptinemia. New Zealand obese (NZO) mice, a model of polygenic obesity, have high levels of circulating leptin and hypertension, and are prone to develop SDB, similarly to human obesity. We hypothesize that systemic leptin receptor blocker Allo-aca will treat hypertension in NZO mice without any effect on body weight, food intake, or breathing. Methods Male NZO mice, 12–13 weeks of age, were treated with Allo-aca (n = 6) or a control peptide Gly11 (n = 12) for 8 consecutive days. Doses of 0.2 mg/kg were administered subcutaneously 2×/day, at 10 AM and 6 PM. Blood pressure was measured by telemetry for 48 h before and during peptide infusion. Ventilation was assessed by whole-body barometric plethysmography, control of breathing was examined by assessing the hypoxic ventilatory response (HVR), and polysomnography was performed during light-phase at baseline and during treatment. Heart rate variability analyses were performed to estimate the cardiac autonomic balance. Results Systemic leptin receptor blockade with Allo-aca did not affect body weight, body temperature, and food intake in NZO mice. Plasma levels of leptin did not change after the treatment with either Allo-aca or the control peptide Gy11. NZO mice were hypertensive at baseline and leptin receptor blocker Allo-aca significantly reduced the mean arterial pressure from 134.9 ± 3.1 to 124.9 ± 5.7 mmHg during the light phase (P < 0.05), whereas the control peptide had no effect. Leptin receptor blockade did not change the heart rate or cardiac autonomic balance. Allo-aca did not affect minute ventilation under normoxic or hypoxic conditions and HVR. Ventilation, apnea index, and oxygen desaturation during NREM and REM sleep did not change with leptin receptor blockade. Conclusion Systemic leptin receptor blockade attenuates hypertension in NZO mice, but does not exacerbate obesity and SDB. Thus, leptin receptor blockade represents a potential pharmacotherapy for obesity-associated hypertension.
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Affiliation(s)
- Lenise J Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Mi-Kyung Shin
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Laszlo Otvos
- Institute of Medical Microbiology, Semmelweis University, Budapest, Hungary.,Arrevus, Inc., Raleigh, NC, United States.,OLPE, LLC, Audubon, PA, United States
| | - Sergio Tufik
- Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Monica L Andersen
- Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Luu V Pham
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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10
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Bird JD, Leacy JK, Foster GE, Rickards CA, Wilson RJA, O'Halloran KD, Jendzjowsky NG, Pentz BA, Byman BRM, Thrall SF, Skalk AL, Hewitt SA, Steinback CD, Burns D, Ondrus P, Day TA. Time course and magnitude of ventilatory and renal acid-base acclimatization following rapid ascent to and residence at 3,800 m over nine days. J Appl Physiol (1985) 2021; 130:1705-1715. [PMID: 33703943 PMCID: PMC11025293 DOI: 10.1152/japplphysiol.00973.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/05/2021] [Indexed: 11/22/2022] Open
Abstract
Rapid ascent to high altitude imposes an acute hypoxic and acid-base challenge, with ventilatory and renal acclimatization countering these perturbations. Specifically, ventilatory acclimatization improves oxygenation, but with concomitant hypocapnia and respiratory alkalosis. A compensatory, renally mediated relative metabolic acidosis follows via bicarbonate elimination, normalizing arterial pH(a). The time course and magnitude of these integrated acclimatization processes are highly variable between individuals. Using a previously developed metric of renal reactivity (RR), indexing the change in arterial bicarbonate concentration (Δ[HCO3-]a; renal response) over the change in arterial pressure of CO2 (Δ[Formula: see text]; renal stimulus), we aimed to characterize changes in RR magnitude following rapid ascent and residence at altitude. Resident lowlanders (n = 16) were tested at 1,045 m (day [D]0) prior to ascent, on D2 within 24 h of arrival, and D9 during residence at 3,800 m. Radial artery blood draws were obtained to measure acid-base variables: [Formula: see text], [HCO3-]a, and pHa. Compared with D0, [Formula: see text] and [HCO3-]a were lower on D2 (P < 0.01) and D9 (P < 0.01), whereas significant changes in pHa (P = 0.072) and RR (P = 0.056) were not detected. As pHa appeared fully compensated on D2 and RR did not increase significantly from D2 to D9, these data demonstrate renal acid-base compensation within 24 h at moderate steady-state altitude. Moreover, RR was strongly and inversely correlated with ΔpHa on D2 and D9 (r≤ -0.95; P < 0.0001), suggesting that a high-gain renal response better protects pHa. Our study highlights the differential time course, magnitude, and variability of integrated ventilatory and renal acid-base acclimatization following rapid ascent and residence at high altitude.NEW & NOTEWORTHY We assessed the time course, magnitude, and variability of integrated ventilatory and renal acid-base acclimatization with rapid ascent and residence at 3,800 m. Despite reductions in [Formula: see text] upon ascent, pHa was normalized within 24 h of arrival at 3,800 m through renal compensation (i.e., bicarbonate elimination). Renal reactivity (RR) was unchanged between days 2 and 9, suggesting a lack of plasticity at moderate steady-state altitude. RR was strongly correlated with ΔpHa, suggesting that a high-gain renal response better protects pHa.
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Affiliation(s)
- Jordan D Bird
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Jack K Leacy
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Sciences Centre, Fort Worth, Texas
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Nicholas G Jendzjowsky
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, California
| | - Brandon A Pentz
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Britta R M Byman
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Scott F Thrall
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Alexandra L Skalk
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Sarah A Hewitt
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - David Burns
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Peter Ondrus
- Department of Family Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
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11
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Arias-Reyes C, Soliz J, Joseph V. Mice and Rats Display Different Ventilatory, Hematological, and Metabolic Features of Acclimatization to Hypoxia. Front Physiol 2021; 12:647822. [PMID: 33776799 PMCID: PMC7994900 DOI: 10.3389/fphys.2021.647822] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/15/2021] [Indexed: 11/13/2022] Open
Abstract
Phylogeographic studies showed that house mice (Mus musculus) originated in the Himalayan region, while common rats (Rattus rattus and Rattus norvegicus) come from the lowlands of China and India. Accordingly, it has been proposed that its origins gave mice, but not rats, the ability to invade ecological niches at high altitudes (pre-adaptation). This proposal is strongly supported by the fact that house mice are distributed throughout the world, while common rats are practically absent above 2,500 m. Considering that the ability of mammals to colonize high-altitude environments (>2,500 m) is limited by their capability to tolerate reduced oxygen availability, in this work, we hypothesize that divergences in the ventilatory, hematological, and metabolic phenotypes of mice and rats establish during the process of acclimatization to hypoxia (Hx). To test this hypothesis male FVB mice and Sprague-Dawley (SD) rats were exposed to Hx (12% O2) for 0 h (normoxic controls), 6 h, 1, 7, and 21 days. We assessed changes in ventilatory [minute ventilation (VE), respiratory frequency (fR), and tidal volume (VT)], hematological (hematocrit and hemoglobin concentration), and metabolic [whole-body O2 consumption (VO2) and CO2 production (VCO2), and liver mitochondrial oxygen consumption rate (OCR) parameters]. Compared to rats, results in mice show increased ventilatory, metabolic, and mitochondrial response. In contrast, rats showed quicker and higher hematological response than mice and only minor ventilatory and metabolic adjustments. Our findings may explain, at least in part, why mice, but not rats, were able to colonize high-altitude habitats.
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Affiliation(s)
- Christian Arias-Reyes
- Centre de Recherche de l'Institute Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Jorge Soliz
- Centre de Recherche de l'Institute Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Vincent Joseph
- Centre de Recherche de l'Institute Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada
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12
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Khor YH, Ryerson CJ, Landry SA, Howard ME, Churchward TJ, Edwards BA, Hamilton GS, Joosten SA. Interstitial lung disease and obstructive sleep apnea. Sleep Med Rev 2021; 58:101442. [PMID: 33561604 DOI: 10.1016/j.smrv.2021.101442] [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: 08/04/2020] [Revised: 09/30/2020] [Accepted: 10/29/2020] [Indexed: 12/11/2022]
Abstract
Obstructive sleep apnea (OSA) is one of the most common comorbidities in patients with interstitial lung disease (ILD). Growing evidence highlights the significance of sleep disturbance on health outcomes in this population. The relationships between ILD and OSA are complex and possibly bidirectional, with multiple mechanisms postulated for the pathogenic and physiologic links. This review synthesizes current evidence and hypotheses regarding different aspects of the relationships between ILD and OSA, emphasizing the interactions between epidemiology, pathogenesis, and pathophysiology.
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Affiliation(s)
- Yet H Khor
- Department of Respiratory and Sleep Medicine, Austin Health, Heidelberg, Victoria, Australia; Institute for Breathing and Sleep, Heidelberg, Victoria, Australia; Faculty of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher J Ryerson
- Centre for Heart Lung Innovation, Providence Health Care, Vancouver, BC, Canada; Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Shane A Landry
- Sleep and Circadian Medicine Laboratory, Department of Physiology, Monash University, Victoria, Australia; School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Australia
| | - Mark E Howard
- Department of Respiratory and Sleep Medicine, Austin Health, Heidelberg, Victoria, Australia; Institute for Breathing and Sleep, Heidelberg, Victoria, Australia; Faculty of Medicine, University of Melbourne, Melbourne, Victoria, Australia; School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Australia
| | - Thomas J Churchward
- Department of Respiratory and Sleep Medicine, Austin Health, Heidelberg, Victoria, Australia; Institute for Breathing and Sleep, Heidelberg, Victoria, Australia
| | - Bradley A Edwards
- Sleep and Circadian Medicine Laboratory, Department of Physiology, Monash University, Victoria, Australia; School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Australia
| | - Garun S Hamilton
- Monash Lung and Sleep, Victoria, Australia; School of Clinical Sciences, Monash University, Victoria, Australia
| | - Simon A Joosten
- Monash Lung and Sleep, Victoria, Australia; School of Clinical Sciences, Monash University, Victoria, Australia.
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13
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Busch SA, van Diepen S, Roberts R, Steele AR, Berthelsen LF, Smorschok MP, Bourgoin C, Steinback CD. Short-term hypoxia does not promote arrhythmia during voluntary apnea. Physiol Rep 2021; 9:e14703. [PMID: 33426815 PMCID: PMC7797307 DOI: 10.14814/phy2.14703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 12/06/2020] [Indexed: 12/19/2022] Open
Abstract
The presence of bradycardic arrhythmias during volitional apnea at altitude may be caused by chemoreflex activation/sensitization. We investigated whether bradyarrhythmic episodes became prevalent in apnea following short‐term hypoxia exposure. Electrocardiograms (ECG; lead II) were collected from 22 low‐altitude residents (F = 12; age=25 ± 5 years) at 671 m. Participants were exposed to normobaric hypoxia (Spo2 ~79 ± 3%) over a 5‐h period. ECG rhythms were assessed during both free‐breathing and maximal volitional end‐expiratory and end‐inspiratory apnea at baseline during normoxia and hypoxia exposure (20 min [AHX]; 5 h [HX5]). Free‐breathing HR became elevated at AHX (78 ± 10 bpm; p < 0.0001) and HX5 (80 ± 12 bpm; p < 0.0001) compared to normoxia (68 ± 10 bpm), whereas apnea caused significant bradycardia at AHX (nadir end‐expiratory −17 ± 14 bpm; p < 0.001) and HX5 (nadir end‐expiratory −19 ± 15 bpm; p < 0.001), but not during normoxia (nadir end‐expiratory −4 ± 13 bpm), with no difference in bradycardia responses between apneas at AHX and HX5. Conduction abnormalities were noted in five participants during normoxia (Premature Ventricular Contraction, Sinus Pause, Junctional Rhythm, Atrial Foci), which remained unchanged during apnea at AHX and HX5 (Premature Ventricular Contraction, Premature Atrial Contraction, Sinus Pause). End‐inspiratory apneas were overall longer across conditions (normoxia p < 0.05; AHX p < 0.01; HX5 p < 0.001), with comparable HR responses to end‐expiratory and fewer occurrences of arrhythmia. While short‐term hypoxia is sufficient to elicit bradycardia during apnea, the occurrence of arrhythmias in response to apnea was not affected. These findings indicate that previously observed bradyarrhythmic events in untrained individuals at altitude only become prevalent following chronic hypoxia specificlly.
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Affiliation(s)
- Stephen A Busch
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Sean van Diepen
- Department of Critical Care and Divison of Cardiology, Department of Medicine, University of Alberta, Edmonton, Canada
| | - Richard Roberts
- Department of Physiology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Canada
| | - Andrew R Steele
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Lindsey F Berthelsen
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Megan P Smorschok
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Cody Bourgoin
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Craig D Steinback
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
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14
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Conde SV, Sacramento JF, Martins FO. Immunity and the carotid body: implications for metabolic diseases. Bioelectron Med 2020; 6:24. [PMID: 33353562 PMCID: PMC7756955 DOI: 10.1186/s42234-020-00061-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/24/2020] [Indexed: 12/14/2022] Open
Abstract
Neuro-immune communication has gained enormous interest in recent years due to increasing knowledge of the way in which the brain coordinates functional alterations in inflammatory and autoimmune responses, and the mechanisms of neuron-immune cell interactions in the context of metabolic diseases such as obesity and type 2 diabetes. In this review, we will explain how this relationship between the nervous and immune system impacts the pro- and anti-inflammatory pathways with specific reference to the hypothalamus-pituitary-adrenal gland axis and the vagal reflex and will explore the possible involvement of the carotid body (CB) in the neural control of inflammation. We will also highlight the mechanisms of vagal anti-inflammatory reflex control of immunity and metabolism, and the consequences of functional disarrangement of this reflex in settlement and development of metabolic diseases, with special attention to obesity and type 2 diabetes. Additionally, the role of CB in the interplay between metabolism and immune responses will be discussed, with specific reference to the different stimuli that promote CB activation and the balance between sympathetic and parasympathetic in this context. In doing so, we clarify the multivarious neuronal reflexes that coordinate tissue-specific responses (gut, pancreas, adipose tissue and liver) critical to metabolic control, and metabolic disease settlement and development. In the final section, we will summarize how electrical modulation of the carotid sinus nerve may be utilized to adjust these reflex responses and thus control inflammation and metabolic diseases, envisioning new therapeutics horizons.
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Affiliation(s)
- Silvia V Conde
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, Rua Câmara Pestana, n°6, Edifício 2, piso 3, 1150-274, Lisbon, Portugal.
| | - Joana F Sacramento
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, Rua Câmara Pestana, n°6, Edifício 2, piso 3, 1150-274, Lisbon, Portugal
| | - Fatima O Martins
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, Rua Câmara Pestana, n°6, Edifício 2, piso 3, 1150-274, Lisbon, Portugal
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15
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Bazilio DS, Rodrigues KL, Moraes DJA, Machado BH. Distinct cardiovascular and respiratory responses to short-term sustained hypoxia in juvenile Sprague Dawley and Wistar Hannover rats. Auton Neurosci 2020; 230:102746. [PMID: 33260056 DOI: 10.1016/j.autneu.2020.102746] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 12/01/2022]
Abstract
Short-term sustained hypoxia (SH) elicits active expiration, augmented late-expiratory (late-E) sympathetic activity, increased arterial pressure and ventilation, and amplified sympathetic and abdominal expiratory responses to chemoreflex activation in rats of the Wistar-Ribeirão Preto (WRP) strain. Herein, we investigated whether SH can differentially affect the cardiovascular and respiratory outcomes of Sprague-Dawley (SD) and Wistar Hannover (WH) rats and compared the results with previous data using WRP rats. For this, we exposed SD and WH rats to SH (FiO2 = 0.1) for 24 h and evaluated arterial pressure, sympathetic activity, and respiratory pattern. SD rats presented increased arterial pressure, respiratory rate and tidal volume, as well as augmented late-E expiratory motor output and increased sympathetic outflow due to post-inspiratory and late-E sympathetic overactivity. WH rats presented reduced changes, suggesting lower responsiveness of this strain to this SH protocol. The magnitudes of changes in sympathetic and abdominal expiratory motor activities to chemoreflex activation in SD rats were reduced by SH. Pressor responses to chemoreflex activation were shown to be blunted in SD and WH rats after SH. The data are showing that SD, WH, and WRP rat strains exhibit marked differences in their cardiovascular, autonomic and respiratory responses to 24-h SH and draw attention to the importance of rat strain for studies exploring the underlying mechanisms involved in the neuronal changes induced by the experimental model of SH.
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Affiliation(s)
- Darlan S Bazilio
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil
| | - Karla L Rodrigues
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil
| | - Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil
| | - Benedito H Machado
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, SP, Brazil.
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16
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Exploring the Mediators that Promote Carotid Body Dysfunction in Type 2 Diabetes and Obesity Related Syndromes. Int J Mol Sci 2020; 21:ijms21155545. [PMID: 32756352 PMCID: PMC7432672 DOI: 10.3390/ijms21155545] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/26/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022] Open
Abstract
Carotid bodies (CBs) are peripheral chemoreceptors that sense changes in blood O2, CO2, and pH levels. Apart from ventilatory control, these organs are deeply involved in the homeostatic regulation of carbohydrates and lipid metabolism and inflammation. It has been described that CB dysfunction is involved in the genesis of metabolic diseases and that CB overactivation is present in animal models of metabolic disease and in prediabetes patients. Additionally, resection of the CB-sensitive nerve, the carotid sinus nerve (CSN), or CB ablation in animals prevents and reverses diet-induced insulin resistance and glucose intolerance as well as sympathoadrenal overactivity, meaning that the beneficial effects of decreasing CB activity on glucose homeostasis are modulated by target-related efferent sympathetic nerves, through a reflex initiated in the CBs. In agreement with our pre-clinical data, hyperbaric oxygen therapy, which reduces CB activity, improves glucose homeostasis in type 2 diabetes patients. Insulin, leptin, and pro-inflammatory cytokines activate the CB. In this manuscript, we review in a concise manner the putative pathways linking CB chemoreceptor deregulation with the pathogenesis of metabolic diseases and discuss and present new data that highlight the roles of hyperinsulinemia, hyperleptinemia, and chronic inflammation as major factors contributing to CB dysfunction in metabolic disorders.
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17
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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: 7] [Impact Index Per Article: 1.8] [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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18
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Leacy JK, Linares AM, Zouboules SM, Rampuri ZH, Bird JD, Herrington BA, Mann LM, Soriano JE, Thrall SF, Kalker A, Brutsaert TD, O'Halloran KD, Sherpa MT, Day TA. Cardiorespiratory hysteresis during incremental high‐altitude ascent–descent quantifies the magnitude of ventilatory acclimatization. Exp Physiol 2020; 106:139-150. [DOI: 10.1113/ep088488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 05/13/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Jack K. Leacy
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
- Department of Physiology School of Medicine College of Medicine & Health University College Cork Cork Ireland
| | - Andrea M. Linares
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Shaelynn M. Zouboules
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Zahrah H. Rampuri
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Jordan D. Bird
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Brittney A. Herrington
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Leah M. Mann
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Jan E. Soriano
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Scott F. Thrall
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Anne Kalker
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
- Radboud University Nijmegen The Netherlands
| | | | - Ken D. O'Halloran
- Department of Physiology School of Medicine College of Medicine & Health University College Cork Cork Ireland
| | | | - Trevor A. Day
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
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19
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Blood and urine biomarkers associated with long-term respiratory dysfunction following neonatal hyperoxia exposure: Implications for prematurity and risk of SIDS. Respir Physiol Neurobiol 2020; 279:103465. [PMID: 32450147 DOI: 10.1016/j.resp.2020.103465] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/06/2020] [Accepted: 05/20/2020] [Indexed: 12/15/2022]
Abstract
Former preterm infants, many of whom required supplemental O2 support, exhibit sleep disordered breathing and attenuated ventilatory responses to acute hypoxia (HVR) beyond their NICU stay. There is an increasing awareness that early detection of biomarkers in biological fluids may be useful predictors/identifiers of short- and long-term morbidities. In the present study, we identified serotonin (5-HT), dopamine (DA) and hyaluronan (HA) as three potential biomarkers that may be increased by neonatal hyperoxia and tested whether they would be associated with an impaired HVR in a rat model of supplemental O2 exposure. Neonatal rats (postnatal age (P) 6 days, P6) exposed to hyperoxia (40% FIO2, 24 h/day between P1-P5 days of age) exhibited an attenuated early (1 min), but not the late (4-5 min) phase of the HVR compared to normoxia control rats; the attenuated early phase HVR was associated with increased levels of DA (urine and serum), 5-HT (platelet poor plasma only, PPP), and HA (serum only). At P21, both the early and late phases of the HVR were attenuated, but serum and urine levels of all 3 biomarkers were similar to age-matched control rats. These data indicate that changes in several serum and/or urine biomarkers (5-HT, DA, and HA) following short-term (days) neonatal hyperoxia can signify long-term (weeks) respiratory control dysfunction. Further studies are needed to determine whether early detection of similar biomarkers could be convenient predictors of increased risk of abnormalities in respiratory control including sleep disordered breathing in former preterm infants who had received prior supplemental O2 and who might also be at increased risk of SIDS.
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20
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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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21
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Cardiorespiratory and thermal responses to hypercapnia in chickens exposed to CO 2 during embryonic development. Respir Physiol Neurobiol 2019; 273:103317. [PMID: 31654812 DOI: 10.1016/j.resp.2019.103317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 10/07/2019] [Accepted: 10/07/2019] [Indexed: 12/27/2022]
Abstract
The concentration of CO2 in the environment surrounding the embryo impacts development and may also influence the cardiorespiratory responses after hatching. Therefore, we aimed to evaluate the cardiorespiratory and thermal responses to hypercapnia in chicks that were exposed to CO2 during embryonic development, i.e., incubation. Embryos were incubated without and with a gradual increase in CO2 concentration up to 1 % during the first ten days of incubation. Ten-day-old chicks (males and females) were again acutely exposed to hypercapnia (7 % CO2), or to room air (normocapnia) and pulmonary ventilation, arterial pH and blood gases, arterial blood pressure and heart rate, body temperature (Tb) and oxygen consumption (V⋅O2) were measured. Compared to control animals, male chicks incubated with 1 % CO2 presented an attenuated ventilatory response to hypercapnia (P < 0.05), whereas no difference was found in the hypercapnic ventilatory response in both female chick groups (0 % vs 1 % CO2 incubation). Hypercapnia induced bradycardia in all groups (P < 0.001). The CO2 exposure during incubation did not alter the cardiovascular responses to hypercapnia in post-hatch animals. There were no significant effects of incubation treatment (0 % vs 1 % CO2) or sex in the mean arterial pressure, Tb, and V⋅O2 of animals in normocapnia and hypercapnia. As for the V⋅E/V⋅O2, hypercapnia caused an increase in both groups (P < 0.05), regardless of incubation treatment. In conclusion, among cardiorespiratory and metabolic variables, the ventilatory response to hypercapnia can be attenuated by pre-exposure to 1 % CO2 during embryonic development, especially in male chicks up to 10 days.
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22
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Storz JF, Scott GR. Life Ascending: Mechanism and Process in Physiological Adaptation to High-Altitude Hypoxia. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2019; 50:503-526. [PMID: 33033467 DOI: 10.1146/annurev-ecolsys-110218-025014] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To cope with the reduced availability of O2 at high altitude, air-breathing vertebrates have evolved myriad adjustments in the cardiorespiratory system to match tissue O2 delivery with metabolic O2 demand. We explain how changes at interacting steps of the O2 transport pathway contribute to plastic and evolved changes in whole-animal aerobic performance under hypoxia. In vertebrates native to high altitude, enhancements of aerobic performance under hypoxia are attributable to a combination of environmentally induced and evolved changes in multiple steps of the pathway. Additionally, evidence suggests that many high-altitude natives have evolved mechanisms for attenuating maladaptive acclimatization responses to hypoxia, resulting in counter-gradient patterns of altitudinal variation for key physiological phenotypes. For traits that exhibit counteracting environmental and genetic effects, evolved changes in phenotype may be cryptic under field conditions and can only be revealed by rearing representatives of high-and low-altitude populations under standardized environmental conditions to control for plasticity.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada
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23
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Majewski S, Szewczyk K, Białas AJ, Miłkowska-Dymanowska J, Kurmanowska Z, Górski P. Assessment of microvascular function in vivo using flow mediated skin fluorescence (FMSF) in patients with obstructive lung diseases: A preliminary study. Microvasc Res 2019; 127:103914. [PMID: 31472204 DOI: 10.1016/j.mvr.2019.103914] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/26/2019] [Accepted: 08/27/2019] [Indexed: 12/23/2022]
Abstract
BACKGROUND Cardiovascular diseases play an important role in the morbidity and mortality of patients with obstructive lung diseases. Impaired vascular endothelial function seems to be a key element linking obstructive lung disease and cardiovascular disease. Recently developed technique named flow mediated skin fluorescence (FMSF) is a novel, non-invasive tool to study microvascular function. METHODS Total of 69 volunteers including 26 patients with chronic obstructive pulmonary disease (COPD), 23 patients with asthma and 20 healthy subjects underwent microvascular function assessments using FMSF. FMSF assessments were composed of measurements of reduced form of nicotinamide adenine dinucleotide (NADH) fluorescence intensity signal during brachial artery occlusion - ischemic response (IRmax) and immediately after release of occlusion - hyperemic response (HRmax). Associations of microvascular function with clinical and biochemical characteristics of studied subjects were also evaluated. RESULTS The median value of IRmax was significantly lower in COPD subjects (2.4 [1.0-6.7] %) compared with healthy subjects (9.6 [3.7-13.5] %; p < 0.01). The mean value of HRmax was also significantly reduced in COPD subjects (9.7 (4.5) %) compared with both asthma subjects (12.1 (3.5) %; p < 0.05) and healthy control subjects (13.4 (2.9) %; p < 0.01). CONCLUSIONS The FMSF technique makes it possible to identify impairments of the microvascular function in patients with COPD, but not in asthma patients. These exploratory findings require further validation in a larger patients cohort.
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Affiliation(s)
- Sebastian Majewski
- Department of Pneumology and Allergy, Medical University of Lodz, Lodz, Poland.
| | - Karolina Szewczyk
- Department of Pneumology and Allergy, Medical University of Lodz, Lodz, Poland
| | - Adam Jerzy Białas
- Department of Pneumology and Allergy, Medical University of Lodz, Lodz, Poland
| | | | - Zofia Kurmanowska
- Department of Pneumology and Allergy, Medical University of Lodz, Lodz, Poland
| | - Paweł Górski
- Department of Pneumology and Allergy, Medical University of Lodz, Lodz, Poland
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24
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Mosqueira M, Iturriaga R. Chronic hypoxia changes gene expression profile of primary rat carotid body cells: consequences on the expression of NOS isoforms and ET-1 receptors. Physiol Genomics 2019; 51:109-124. [DOI: 10.1152/physiolgenomics.00114.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sustained chronic hypoxia (CH) produces morphological and functional changes in the carotid body (CB). Nitric oxide (NO) and endothelin-1 (ET-1) play a major role as modulators of the CB oxygen chemosensory process. To characterize the effects of CH related to normoxia (Nx) on gene expression, particularly on ET-1 and NO pathways, primary cultures of rat CB cells were exposed to 7 days of CH. Total RNA was extracted, and cDNA-32P was synthesized and hybridized with 1,185 genes printed on a nylon membrane Atlas cDNA Expression Array. Out of 324 differentially expressed genes, 184 genes were upregulated, while 140 genes were downregulated. The cluster annotation and protein network analyses showed that both NO and ET-1 signaling pathways were significantly enriched and key elements of each pathway were differentially expressed. Thus, we assessed the effect of CH at the protein level of nitric oxide synthase (NOS) isoforms and ET-1 receptors. CH induced an increase in the expression of endothelial NOS, inducible NOS, and ETB. During CH, the administration of SNAP, a NO donor, upregulated ETB. Treatment with Tezosentan (ET-1 receptor blocker) during CH upregulated all three NOS isoforms, while the NOS blocker L-NAME induced upregulation of iNOS and ETB and downregulated the protein levels of ETA. These results show that CH for 7 days changed the cultured cell CB gene expression profile, the NO and ET-1 signaling pathways were highly enriched, and these two signaling pathways interfered with the protein expression of each other.
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Affiliation(s)
- Matías Mosqueira
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago Chile
- Cardio-Ventilatory Muscle Physiology Laboratory, Institute of Physiology and Pathophysiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago Chile
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Ivy CM, Lague SL, York JM, Chua BA, Alza L, Cheek R, Dawson NJ, Frappell PB, McCracken KG, Milsom WK, Scott GR. Control of breathing and respiratory gas exchange in high-altitude ducks native to the Andes. ACTA ACUST UNITED AC 2019; 222:jeb.198622. [PMID: 30846536 DOI: 10.1242/jeb.198622] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/03/2019] [Indexed: 11/20/2022]
Abstract
We examined the control of breathing and respiratory gas exchange in six species of high-altitude duck that independently colonized the high Andes. We compared ducks from high-altitude populations in Peru (Lake Titicaca at ∼3800 m above sea level; Chancay River at ∼3000-4100 m) with closely related populations or species from low altitude. Hypoxic ventilatory responses were measured shortly after capture at the native altitude. In general, ducks responded to acute hypoxia with robust increases in total ventilation and pulmonary O2 extraction. O2 consumption rates were maintained or increased slightly in acute hypoxia, despite ∼1-2°C reductions in body temperature in most species. Two high-altitude taxa - yellow-billed pintail and torrent duck - exhibited higher total ventilation than their low-altitude counterparts, and yellow-billed pintail exhibited greater increases in pulmonary O2 extraction in severe hypoxia. In contrast, three other high-altitude taxa - Andean ruddy duck, Andean cinnamon teal and speckled teal - had similar or slightly reduced total ventilation and pulmonary O2 extraction compared with low-altitude relatives. Arterial O2 saturation (S aO2 ) was elevated in yellow-billed pintails at moderate levels of hypoxia, but there were no differences in S aO2 in other high-altitude taxa compared with their close relatives. This finding suggests that improvements in S aO2 in hypoxia can require increases in both breathing and haemoglobin-O2 affinity, because the yellow-billed pintail was the only high-altitude duck with concurrent increases in both traits compared with its low-altitude relative. Overall, our results suggest that distinct physiological strategies for coping with hypoxia can exist across different high-altitude lineages, even among those inhabiting very similar high-altitude habitats.
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Affiliation(s)
- Catherine M Ivy
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Sabine L Lague
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Julia M York
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4.,Department of Integrative Biology, University of Texas at Austin, TX 78712, USA
| | - Beverly A Chua
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Luis Alza
- Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, FL 33146, USA.,Division of Ornithology, Centro de Ornitologia y Biodiversidad, Lima 33, Peru.,Department of Biology and Wildlife, Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK 99755, USA
| | - Rebecca Cheek
- Department of Biology and Wildlife, Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK 99755, USA
| | - Neal J Dawson
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Peter B Frappell
- Zoology Department, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Kevin G McCracken
- Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, FL 33146, USA.,Division of Ornithology, Centro de Ornitologia y Biodiversidad, Lima 33, Peru.,Department of Biology and Wildlife, Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK 99755, USA.,Human Genetics and Genomics, University of Miller School of Medicine, Miami, FL 33136, USA
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
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Pulgar-Sepúlveda R, Varas R, Iturriaga R, Del Rio R, Ortiz FC. Carotid Body Type-I Cells Under Chronic Sustained Hypoxia: Focus on Metabolism and Membrane Excitability. Front Physiol 2018; 9:1282. [PMID: 30283346 PMCID: PMC6157308 DOI: 10.3389/fphys.2018.01282] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/24/2018] [Indexed: 12/23/2022] Open
Abstract
Chronic sustained hypoxia (CSH) evokes ventilatory acclimatization characterized by a progressive hyperventilation due to a potentiation of the carotid body (CB) chemosensory response to hypoxia. The transduction of the hypoxic stimulus in the CB begins with the inhibition of K+ currents in the chemosensory (type-I) cells, which in turn leads to membrane depolarization, Ca2+ entry and the subsequent release of one- or more-excitatory neurotransmitters. Several studies have shown that CSH modifies both the level of transmitters and chemoreceptor cell metabolism within the CB. Most of these studies have been focused on the role played by such putative transmitters and modulators of CB chemoreception, but less is known about the effect of CSH on metabolism and membrane excitability of type-I cells. In this mini-review, we will examine the effects of CSH on the ion channels activity and excitability of type-I cell, with a particular focus on the effects of CSH on the TASK-like background K+ channel. We propose that changes on TASK-like channel activity induced by CSH may contribute to explain the potentiation of CB chemosensory activity.
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Affiliation(s)
- Raúl Pulgar-Sepúlveda
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Rodrigo Varas
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Envejecimiento y Regeneración, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Fernando C. Ortiz
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
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Ivy CM, Scott GR. Evolved changes in breathing and CO 2 sensitivity in deer mice native to high altitudes. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1027-R1037. [PMID: 30183337 DOI: 10.1152/ajpregu.00220.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We examined the control of breathing by O2 and CO2 in deer mice native to high altitude to help uncover the physiological specializations used to cope with hypoxia in high-altitude environments. Highland deer mice ( Peromyscus maniculatus) and lowland white-footed mice ( P. leucopus) were bred in captivity at sea level. The first and second generation progeny of each population was raised to adulthood and then acclimated to normoxia or hypobaric hypoxia (12 kPa O2, simulating hypoxia at ~4,300 m) for 6-8 wk. Ventilatory responses to poikilocapnic hypoxia (stepwise reductions in inspired O2) and hypercapnia (stepwise increases in inspired CO2) were then compared between groups. Both generations of lowlanders appeared to exhibit ventilatory acclimatization to hypoxia (VAH), in which hypoxia acclimation enhanced the hypoxic ventilatory response and/or made the breathing pattern more effective (higher tidal volumes and lower breathing frequencies at a given total ventilation). In contrast, hypoxia acclimation had no effect on breathing in either generation of highlanders, and breathing was generally similar to hypoxia-acclimated lowlanders. Therefore, attenuation of VAH may be an evolved feature of highlanders that persists for multiple generations in captivity. Hypoxia acclimation increased CO2 sensitivity of breathing, but in this case, the effect of hypoxia acclimation was similar in highlanders and lowlanders. Our results suggest that highland deer mice have evolved high rates of alveolar ventilation that are unaltered by exposure to chronic hypoxia, but they have preserved ventilatory sensitivity to CO2.
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Affiliation(s)
- Catherine M Ivy
- Department of Biology, McMaster University , Hamilton, ON , Canada
| | - Graham R Scott
- Department of Biology, McMaster University , Hamilton, ON , Canada
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Ivy CM, York JM, Lague SL, Chua BA, Alza L, McCracken KG, Milsom WK, Scott GR. Validation of a Pulse Oximetry System for High-Altitude Waterfowl by Examining the Hypoxia Responses of the Andean Goose (Chloephaga melanoptera). Physiol Biochem Zool 2018. [DOI: 10.1086/697053] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Leonard EM, Salman S, Nurse CA. Sensory Processing and Integration at the Carotid Body Tripartite Synapse: Neurotransmitter Functions and Effects of Chronic Hypoxia. Front Physiol 2018; 9:225. [PMID: 29615922 PMCID: PMC5864924 DOI: 10.3389/fphys.2018.00225] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 02/28/2018] [Indexed: 12/21/2022] Open
Abstract
Maintenance of homeostasis in the respiratory and cardiovascular systems depends on reflexes that are initiated at specialized peripheral chemoreceptors that sense changes in the chemical composition of arterial blood. In mammals, the bilaterally-paired carotid bodies (CBs) are the main peripheral chemoreceptor organs that are richly vascularized and are strategically located at the carotid bifurcation. The CBs contribute to the maintenance of O2, CO2/H+, and glucose homeostasis and have attracted much clinical interest because hyperactivity in these organs is associated with several pathophysiological conditions including sleep apnea, obstructive lung disease, heart failure, hypertension, and diabetes. In response to a decrease in O2 availability (hypoxia) and elevated CO2/H+ (acid hypercapnia), CB receptor type I (glomus) cells depolarize and release neurotransmitters that stimulate apposed chemoafferent nerve fibers. The central projections of those fibers in turn activate cardiorespiratory centers in the brainstem, leading to an increase in ventilation and sympathetic drive that helps restore blood PO2 and protect vital organs, e.g., the brain. Significant progress has been made in understanding how neurochemicals released from type I cells such as ATP, adenosine, dopamine, 5-HT, ACh, and angiotensin II help shape the CB afferent discharge during both normal and pathophysiological conditions. However, type I cells typically occur in clusters and in addition to their sensory innervation are ensheathed by the processes of neighboring glial-like, sustentacular type II cells. This morphological arrangement is reminiscent of a "tripartite synapse" and emerging evidence suggests that paracrine stimulation of type II cells by a variety of CB neurochemicals may trigger the release of "gliotransmitters" such as ATP via pannexin-1 channels. Further, recent data suggest novel mechanisms by which dopamine, acting via D2 receptors (D2R), may inhibit action potential firing at petrosal nerve endings. This review will update current ideas concerning the presynaptic and postsynaptic mechanisms that underlie chemosensory processing in the CB. Paracrine signaling pathways will be highlighted, and particularly those that allow the glial-like type II cells to participate in the integrated sensory response during exposures to chemostimuli, including acute and chronic hypoxia.
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Affiliation(s)
- Erin M Leonard
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Shaima Salman
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Colin A Nurse
- Department of Biology, McMaster University, Hamilton, ON, Canada
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Molecular Characterization of Equilibrative Nucleoside Transporters in the Rat Carotid Body and Their Regulation by Chronic Hypoxia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1071:43-50. [DOI: 10.1007/978-3-319-91137-3_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Ivy CM, Scott GR. Control of breathing and ventilatory acclimatization to hypoxia in deer mice native to high altitudes. Acta Physiol (Oxf) 2017. [PMID: 28640969 DOI: 10.1111/apha.12912] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
AIM We compared the control of breathing and heart rate by hypoxia between high- and low-altitude populations of Peromyscus mice, to help elucidate the physiological specializations that help high-altitude natives cope with O2 limitation. METHODS Deer mice (Peromyscus maniculatus) native to high altitude and congeneric mice native to low altitude (Peromyscus leucopus) were bred in captivity at sea level. The F1 progeny of each population were raised to adulthood and then acclimated to normoxia or hypobaric hypoxia (12 kPa, simulating hypoxia at ~4300 m) for 5 months. Responses to acute hypoxia were then measured during stepwise reductions in inspired O2 fraction. RESULTS Lowlanders exhibited ventilatory acclimatization to hypoxia (VAH), in which hypoxia acclimation enhanced the hypoxic ventilatory response, made breathing pattern more effective (higher tidal volumes and lower breathing frequencies at a given total ventilation), increased arterial O2 saturation and heart rate during acute hypoxia, augmented respiratory water loss and led to significant growth of the carotid body. In contrast, highlanders did not exhibit VAH - exhibiting a fixed increase in breathing that was similar to hypoxia-acclimated lowlanders - and they maintained even higher arterial O2 saturations in hypoxia. However, the carotid bodies of highlanders were not enlarged by hypoxia acclimation and were similar in size to those of normoxic lowlanders. Highlanders also maintained consistently higher heart rates than lowlanders during acute hypoxia. CONCLUSIONS Our results suggest that highland deer mice have evolved high rates of alveolar ventilation and respiratory O2 uptake without the significant enlargement of the carotid bodies that is typical of VAH in lowlanders, possibly to adjust the hypoxic chemoreflex for life in high-altitude hypoxia.
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Affiliation(s)
- C. M. Ivy
- Department of Biology; McMaster University; Hamilton ON Canada
| | - G. R. Scott
- Department of Biology; McMaster University; Hamilton ON Canada
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Salman S, Vollmer C, McClelland GB, Nurse CA. Characterization of ectonucleotidase expression in the rat carotid body: regulation by chronic hypoxia. Am J Physiol Cell Physiol 2017. [PMID: 28637679 DOI: 10.1152/ajpcell.00328.2016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The carotid body (CB) chemoreflex maintains blood Po2 and Pco2/H+ homeostasis and displays sensory plasticity during exposure to chronic hypoxia. Purinergic signaling via P1 and P2 receptors plays a pivotal role in shaping the afferent discharge at the sensory synapse containing catecholaminergic chemoreceptor (type I) cells, glial-like type II cells, and sensory (petrosal) nerve endings. However, little is known about the family of ectonucleotidases that control synaptic nucleotide levels. Using quantitative PCR (qPCR), we first compared expression levels of ectonucleoside triphosphate diphosphohydrolases (NTPDases1,2,3,5,6) and ecto-5'-nucleotidase (E5'Nt/CD73) mRNAs in juvenile rat CB vs. brain, petrosal ganglia, sympathetic (superior cervical) ganglia, and a sympathoadrenal chromaffin (MAH) cell line. In whole CB extracts, qPCR revealed a high relative expression of surface-located members NTPDase1,2 and E5'Nt/CD73, compared with low NTPDase3 expression. Immunofluorescence staining of CB sections or dissociated CB cultures localized NTPDase2,3 and E5'Nt/CD73 protein to the periphery of type I clusters, and in association with sensory nerve fibers and/or isolated type II cells. Interestingly, in CBs obtained from rats reared under chronic hypobaric hypoxia (~60 kPa, equivalent to 4,300 m) for 5-7 days, in addition to the expected upregulation of tyrosine hydroxylase and VEGF mRNAs, there was a significant upregulation of NTPDase3 and E5'Nt/CD73 mRNA, but a downregulation of NTPDase1 and NTPDase2 relative to normoxic controls. We conclude that NTPDase1,2,3 and E5'Nt/CD73 are the predominant surface-located ectonucleotidases in the rat CB and suggest that their differential regulation during chronic hypoxia may contribute to CB plasticity via control of synaptic ATP, ADP, and adenosine pools.
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Affiliation(s)
- Shaima Salman
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Cathy Vollmer
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | | | - Colin A Nurse
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Developmental plasticity in the neural control of breathing. Exp Neurol 2017; 287:176-191. [DOI: 10.1016/j.expneurol.2016.05.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/13/2016] [Accepted: 05/26/2016] [Indexed: 12/14/2022]
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Sunderram J, Semmlow J, Patel P, Rao H, Chun G, Agarwala P, Bhaumik M, Le-Hoang O, Lu SE, Neubauer JA. Heme oxygenase-1-dependent central cardiorespiratory adaptations to chronic intermittent hypoxia in mice. J Appl Physiol (1985) 2016; 121:944-952. [PMID: 27609199 DOI: 10.1152/japplphysiol.00036.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 09/06/2016] [Indexed: 11/22/2022] Open
Abstract
Chronic intermittent hypoxia (CIH) increases sympathetic tone and respiratory instability. Our previous work showed that chronic hypoxia induces the oxygen-sensing enzyme heme oxygenase-1 (HO-1) within the C1 sympathoexcitatory region and the pre-Bötzinger complex (pre-BötC). We therefore examined the effect of CIH on time course of induced expression of HO-1 within these regions and determined whether the induction of HO-1 correlated with changes in respiratory, sigh frequency, and sympathetic responses (spectral analysis of heart rate) to acute hypoxia (10% O2) during 10 days of exposure to CIH in chronically instrumented awake wild-type (WT) and HO-1 null mice (HO-1-/-). HO-1 was induced within the C1 and pre-BötC regions after 1 day of CIH. There were no significant differences in the baseline respiratory parameters between WT and HO-1-/- Prior to CIH, acute hypoxia increased respiratory frequency in both WT and HO-1-/-; however, minute diaphragm electromyogram activity increased in WT but not HO-1-/- The hypoxic respiratory response after 1 and 10 days of CIH was restored in HO-1-/- CIH resulted in an initial significant decline in 1) the hypoxic sigh frequency response, which was restored in WT but not HO-1-/-, and 2) the baseline sympathetic activity in WT and HO-1-/-, which remained stable subsequently in WT but not in HO-1-/- We conclude that 1) CIH induces expression of HO-1 in the C1 and pre-BötC regions within 1 day and 2) HO-1 is necessary for hypoxia respiratory response and contributes to the maintenance of the hypoxic sigh responses and baseline sympathetic activity during CIH.
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Affiliation(s)
- Jag Sunderram
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey;
| | - John Semmlow
- Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Pranav Patel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Harshit Rao
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Glen Chun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Priya Agarwala
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Mantu Bhaumik
- Department of Pediatrics, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey; and
| | - Oanh Le-Hoang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Shou-En Lu
- Department of Biostatistics, Rutgers School of Public Health, Piscataway, New Jersey
| | - Judith A Neubauer
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
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Lague SL, Chua B, Farrell AP, Wang Y, Milsom WK. Altitude matters: differences in cardiovascular and respiratory responses to hypoxia in bar-headed geese reared at high and low altitudes. J Exp Biol 2016; 219:1974-84. [DOI: 10.1242/jeb.132431] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 04/06/2016] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Bar-headed geese (Anser indicus) fly at high altitudes during their migration across the Himalayas and Tibetan plateau. However, we know relatively little about whether rearing at high altitude (i.e. phenotypic plasticity) facilitates this impressive feat because most of what is known about their physiology comes from studies performed at sea level. To provide this information, a comprehensive analysis of metabolic, cardiovascular and ventilatory responses to progressive decreases in the equivalent fractional composition of inspired oxygen (FiO2: 0.21, 0.12, 0.09, 0.07 and 0.05) was made on bar-headed geese reared at either high altitude (3200 m) or low altitude (0 m) and on barnacle geese (Branta leucopsis), a low-altitude migrating species, reared at low altitude (0 m). Bar-headed geese reared at high altitude exhibited lower metabolic rates and a modestly increased hypoxic ventilatory response compared with low-altitude-reared bar-headed geese. Although the in vivo oxygen equilibrium curves and blood-oxygen carrying capacity did not differ between the two bar-headed goose study groups, the blood-oxygen carrying capacity was higher than that of barnacle geese. Resting cardiac output also did not differ between groups and increased at least twofold during progressive hypoxia, initially as a result of increases in stroke volume. However, cardiac output increased at a higher FiO2 threshold in bar-headed geese raised at high altitude. Thus, bar-headed geese reared at high altitude exhibited a reduced oxygen demand at rest and a modest but significant increase in oxygen uptake and delivery during progressive hypoxia compared with bar-headed geese reared at low altitude.
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Affiliation(s)
- Sabine L. Lague
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Beverly Chua
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Anthony P. Farrell
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Yuxiang Wang
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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Pamenter ME, Powell FL. Time Domains of the Hypoxic Ventilatory Response and Their Molecular Basis. Compr Physiol 2016; 6:1345-85. [PMID: 27347896 DOI: 10.1002/cphy.c150026] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ventilatory responses to hypoxia vary widely depending on the pattern and length of hypoxic exposure. Acute, prolonged, or intermittent hypoxic episodes can increase or decrease breathing for seconds to years, both during the hypoxic stimulus, and also after its removal. These myriad effects are the result of a complicated web of molecular interactions that underlie plasticity in the respiratory control reflex circuits and ultimately control the physiology of breathing in hypoxia. Since the time domains of the physiological hypoxic ventilatory response (HVR) were identified, considerable research effort has gone toward elucidating the underlying molecular mechanisms that mediate these varied responses. This research has begun to describe complicated and plastic interactions in the relay circuits between the peripheral chemoreceptors and the ventilatory control circuits within the central nervous system. Intriguingly, many of these molecular pathways seem to share key components between the different time domains, suggesting that varied physiological HVRs are the result of specific modifications to overlapping pathways. This review highlights what has been discovered regarding the cell and molecular level control of the time domains of the HVR, and highlights key areas where further research is required. Understanding the molecular control of ventilation in hypoxia has important implications for basic physiology and is emerging as an important component of several clinical fields. © 2016 American Physiological Society. Compr Physiol 6:1345-1385, 2016.
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Affiliation(s)
| | - Frank L Powell
- Physiology Division, Department of Medicine, University of California San Diego, La Jolla, California, USA
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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: 5.4] [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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Atanasova DY, Lazarov NE. Morphological changes in the rat carotid body following acute sodium nitrite treatment. Respir Physiol Neurobiol 2015; 221:11-8. [PMID: 26528896 DOI: 10.1016/j.resp.2015.10.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/21/2015] [Accepted: 10/23/2015] [Indexed: 11/24/2022]
Abstract
The carotid body (CB) is a small neural crest-derived chemosensory organ that detects the chemical composition of the arterial blood and responds to its changes by regulating breathing. The effects of acute nitrite treatment on the CB morphology in rats were examined by morphometry. We found that 1h after administrating a single dose of sodium nitrite, the CB underwent structural changes characterized by a prominent increase in its size with a marked, several-fold dilation of the blood vessels. The obvious CB enlargement mostly due to apparent vasodilation and glomus cell hypertrophy was at its highest one day later and persisted until the fifth day. 20 days after the treatment, the CB regained its size to the normoxic control state. Morphometric analysis revealed that the CB size increase in treated animals is statistically significant when compared to that of untreated controls. It can be inferred that the nitrite-exposed CB displays remarkable structural plasticity and enlarges its size mostly through vascular expansion.
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Affiliation(s)
- Dimitrinka Y Atanasova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria; Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Nikolai E Lazarov
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria; Department of Anatomy and Histology, Medical University of Sofia, Sofia, Bulgaria.
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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: 2.0] [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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40
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Jonz MG, Zachar PC, Da Fonte DF, Mierzwa AS. Peripheral chemoreceptors in fish: A brief history and a look ahead. Comp Biochem Physiol A Mol Integr Physiol 2015; 186:27-38. [DOI: 10.1016/j.cbpa.2014.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/03/2014] [Accepted: 09/03/2014] [Indexed: 11/24/2022]
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Janes TA, Xu F, Syed NI. Graded hypoxia acts through a network of distributed peripheral oxygen chemoreceptors to produce changes in respiratory behaviour and plasticity. Eur J Neurosci 2015; 42:1858-71. [PMID: 25951609 DOI: 10.1111/ejn.12940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 05/30/2015] [Accepted: 05/02/2015] [Indexed: 01/23/2023]
Abstract
Respiratory behaviour relies critically upon sensory feedback from peripheral oxygen chemoreceptors. During environmental or systemic hypoxia, chemoreceptor input modulates respiratory central pattern generator activity to produce reflex-based increases in respiration and also shapes respiratory plasticity over longer timescales. The best-studied oxygen chemoreceptors are undoubtedly the mammalian carotid bodies; however, questions remain regarding this complex organ's role in shaping respiration in response to varying oxygen levels. Furthermore, many taxa possess distinct oxygen chemoreceptors located within the lungs, airways and cardiovasculature, but the functional advantage of multiple chemoreceptor sites is unclear. In this study, it is demonstrated that a distributed network of peripheral oxygen chemoreceptors exists in Lymnaea stagnalis and significantly modulates aerial respiration. Specifically, Lymnaea breath frequency and duration represent parameters that are shaped by interactions between hypoxic severity and its time-course. Using a combination of behaviour and electrophysiology approaches, the chemosensory pathways underlying hypoxia-induced changes in breath frequency/duration were explored. The current findings demonstrate that breath frequency is uniquely modulated by the known osphradial ganglion oxygen chemoreceptors during moderate hypoxia, while a newly discovered area of pneumostome oxygen chemoreception serves a similar function specifically during more severe hypoxia. Together, these findings suggest that multiple oxygen chemosensory sites, each with their own sensory and modulatory properties, act synergistically to form a functionally distributed network that dynamically shapes respiration in response to changing systemic or environmental oxygen levels. These distributed networks may represent an evolutionarily conserved strategy vis-à-vis respiratory adaptability and have significant implications for the understanding of fundamental respiratory control systems.
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Affiliation(s)
- Tara A Janes
- Department of Cell Biology and Anatomy and the Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3280 Hospital Dr N.W., Calgary, AB, Canada, T2N4Z6
| | - Fenglian Xu
- Department of Cell Biology and Anatomy and the Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3280 Hospital Dr N.W., Calgary, AB, Canada, T2N4Z6
| | - Naweed I Syed
- Department of Cell Biology and Anatomy and the Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3280 Hospital Dr N.W., Calgary, AB, Canada, T2N4Z6
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Lu S, Xin Y, Tang X, Yue F, Wang H, Bai Y, Niu Y, Chen Q. Differences in Hematological Traits between High- and Low-Altitude Lizards (Genus Phrynocephalus). PLoS One 2015; 10:e0125751. [PMID: 25955247 PMCID: PMC4425549 DOI: 10.1371/journal.pone.0125751] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/26/2015] [Indexed: 11/18/2022] Open
Abstract
Phrynocephalus erythrurus (Lacertilia: Agamidae) is considered to be the highest living reptile in the world (about 4500-5000 m above sea level), whereas Phrynocephalus przewalskii inhabits low altitudes (about 1000-1500 m above sea level). Here, we report the differences in hematological traits between these two different Phrynocephalus species. Compared with P. przewalskii, the results indicated that P. erythrurus own higher oxygen carrying capacity by increasing red blood cell count (RBC), hemoglobin concentration ([Hb]) and hematocrit (Hct) and these elevations could promote oxygen carrying capacity without disadvantage of high viscosity. The lower partial pressure of oxygen in arterial blood (PaO2) of P. erythrurus did not cause the secondary alkalosis, which may be attributed to an efficient pulmonary system for oxygen (O2) loading. The elevated blood-O2 affinity in P. erythrurus may be achieved by increasing intrinsic O2 affinity of isoHbs and balancing the independent effects of potential heterotropic ligands. We detected one α-globin gene and three β-globin genes with 1 and 33 amino acid substitutions between these two species, respectively. Molecular dynamics simulation results showed that amino acids substitutions in β-globin chains could lead to the elimination of hydrogen bonds in T-state Hb models of P. erythrurus. Based on the present data, we suggest that P. erythrurus have evolved an efficient oxygen transport system under the unremitting hypobaric hypoxia.
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Affiliation(s)
- Songsong Lu
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Ying Xin
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Xiaolong Tang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Feng Yue
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Huihui Wang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Yucheng Bai
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Yonggang Niu
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Qiang Chen
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
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Kim D, Kim I, Wang J, White C, Carroll JL. Hydrogen sulfide and hypoxia-induced changes in TASK (K2P3/9) activity and intracellular Ca(2+) concentration in rat carotid body glomus cells. Respir Physiol Neurobiol 2015; 215:30-8. [PMID: 25956223 DOI: 10.1016/j.resp.2015.04.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 01/01/2023]
Abstract
Acute hypoxia depolarizes carotid body chemoreceptor (glomus) cells and elevates intracellular Ca(2+) concentration ([Ca(2+)]i). Recent studies suggest that hydrogen sulfide (H2S) may serve as an oxygen sensor/signal in the carotid body during acute hypoxia. To further test such a role for H2S, we studied the effects of H2S on the activity of TASK channel and [Ca(2+)]i, which are considered important for mediating the glomus cell response to hypoxia. Like hypoxia, NaHS (a H2S donor) inhibited TASK activity and elevated [Ca(2+)]i. To inhibit the production of H2S, glomus cells were incubated (3h) with inhibitors of cystathionine-β-synthase and cystathionine-γ-lyase (DL-propargylglycine, aminooxyacetic acid, β-cyano-L-alanine; 0.3 mM). SF7 fluorescence was used to assess the level of H2S production. The inhibitors blocked L-cysteine- and hypoxia-induced elevation of SF7 fluorescence intensity. In cells treated with the inhibitors, hypoxia produced an inhibition of TASK activity and a rise in [Ca(2+)]i, similar in magnitude to those observed in control cells. L-cysteine produced no effect on TASK activity or [Ca(2+)]i and did not affect hypoxia-induced inhibition of TASK and elevation of [Ca(2+)]i. These findings suggest that under normal conditions, H2S is not a major signal in hypoxia-induced modulation of TASK channels and [Ca(2+)]i in isolated glomus cells.
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Affiliation(s)
- Donghee Kim
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States.
| | - Insook Kim
- Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, 13 Children's Way, Little Rock, AR 72202, United States
| | - Jiaju Wang
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States
| | - Carl White
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States
| | - John L Carroll
- Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, 13 Children's Way, Little Rock, AR 72202, United States.
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Bai Z, Voituron N, Wuren T, Jeton F, Jin G, Marchant D, Richalet JP, Ge RL, Pichon AP. Role of glutamate and serotonin on the hypoxic ventilatory response in high-altitude-adapted plateau Pika. Respir Physiol Neurobiol 2015; 212-214:39-45. [PMID: 25890014 DOI: 10.1016/j.resp.2015.03.006] [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: 06/24/2014] [Revised: 03/17/2015] [Accepted: 03/19/2015] [Indexed: 10/23/2022]
Abstract
The highland "plateau Pika" is considered to be adapted to chronic hypoxia. We hypothesized that glutamate N-methyl-D-aspartate (NMDA) and non-NMDA receptors, nitric oxide (NO) synthase, and serotonin are involved in hypoxic ventilatory response (HVR) in Pikas. We tested the effects of NMDA (memantine) and non-NMDA receptors (DNQX) antagonists, NO synthase inhibitor (L-NAME), and selective serotonin reuptake inhibitors (fluoxetine) on ventilation and HVR in Pikas. Ventilatory parameters were measured before and after drug (or vehicle) injections in conscious Pikas at their natural living altitude (PIO2 86 mmHg) and after a hypoxic challenge (PIO2 57 mmHg, 3 min) to assess the influence of peripheral chemoreceptor on HVR. Minute ventilation (VI) and tidal volume (Vt) increased during hypoxic challenge after vehicle injection, whereas the Ti/Ttot ratio remained unchanged. The increase in VI and Vt observed with vehicle at PIO2-57, when compared with PIO2-86, was inhibited after memantine and fluoxetine injection, whereas the DNQX injection increased HVR. At PIO2-57, L-NAME induced an increase in the Ti/Ttot ratio when compared with vehicle. Therefore, the glutamate through NMDA-R/AMPA receptor bindings and serotonin pathway are implicated at the peripheral chemoreceptor level in HVR in Pikas. However, NO influences the ventilatory pattern of Pikas at their habitual living altitude.
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Affiliation(s)
- Zhenzhong Bai
- Research Centre for High Altitude Medicine, Qinghai University Medical College, Xining, Qinghai, PR China
| | - Nicolas Voituron
- Université Paris 13, Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon" EA2363, Bobigny, France; Laboratory of Excellence GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Tana Wuren
- Research Centre for High Altitude Medicine, Qinghai University Medical College, Xining, Qinghai, PR China
| | - Florine Jeton
- Université Paris 13, Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon" EA2363, Bobigny, France; Laboratory of Excellence GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Guoen Jin
- Research Centre for High Altitude Medicine, Qinghai University Medical College, Xining, Qinghai, PR China
| | - Dominique Marchant
- Université Paris 13, Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon" EA2363, Bobigny, France
| | - Jean-Paul Richalet
- Université Paris 13, Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon" EA2363, Bobigny, France; Laboratory of Excellence GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Ri-Li Ge
- Research Centre for High Altitude Medicine, Qinghai University Medical College, Xining, Qinghai, PR China.
| | - Aurélien P Pichon
- Université Paris 13, Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon" EA2363, Bobigny, France; Laboratory of Excellence GR-Ex, PRES Sorbonne Paris Cité, Paris, France.
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Ivy CM, Scott GR. Control of breathing and the circulation in high-altitude mammals and birds. Comp Biochem Physiol A Mol Integr Physiol 2014; 186:66-74. [PMID: 25446936 DOI: 10.1016/j.cbpa.2014.10.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/17/2014] [Accepted: 10/18/2014] [Indexed: 01/07/2023]
Abstract
Hypoxia is an unremitting stressor at high altitudes that places a premium on oxygen transport by the respiratory and cardiovascular systems. Phenotypic plasticity and genotypic adaptation at various steps in the O2 cascade could help offset the effects of hypoxia on cellular O2 supply in high-altitude natives. In this review, we will discuss the unique mechanisms by which ventilation, cardiac output, and blood flow are controlled in high-altitude mammals and birds. Acclimatization to high altitudes leads to some changes in respiratory and cardiovascular control that increase O2 transport in hypoxia (e.g., ventilatory acclimatization to hypoxia). However, acclimatization or development in hypoxia can also modify cardiorespiratory control in ways that are maladaptive for O2 transport. Hypoxia responses that arose as short-term solutions to O2 deprivation (e.g., peripheral vasoconstriction) or regional variation in O2 levels in the lungs (i.e., hypoxic pulmonary vasoconstriction) are detrimental at in chronic high-altitude hypoxia. Evolved changes in cardiorespiratory control have arisen in many high-altitude taxa, including increases in effective ventilation, attenuation of hypoxic pulmonary vasoconstriction, and changes in catecholamine sensitivity of the heart and systemic vasculature. Parallel evolution of some of these changes in independent highland lineages supports their adaptive significance. Much less is known about the genomic bases and potential interactive effects of adaptation, acclimatization, developmental plasticity, and trans-generational epigenetic transfer on cardiorespiratory control. Future work to understand these various influences on breathing and circulation in high-altitude natives will help elucidate how complex physiological systems can be pushed to their limits to maintain cellular function in hypoxia.
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Affiliation(s)
- Catherine M Ivy
- Department of Biology, McMaster University, Hamilton, ON, Canada.
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, ON, Canada
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Expression of neurotrophic factors and their receptors in the carotid body of spontaneously hypertensive rats. Respir Physiol Neurobiol 2014; 202:6-15. [DOI: 10.1016/j.resp.2014.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 06/25/2014] [Accepted: 06/25/2014] [Indexed: 01/19/2023]
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Zhang P, Downey HF, Chen S, Shi X. Two-week normobaric intermittent hypoxia exposures enhance oxyhemoglobin equilibrium and cardiac responses during hypoxemia. Am J Physiol Regul Integr Comp Physiol 2014; 307:R721-30. [PMID: 25056104 DOI: 10.1152/ajpregu.00191.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intermittent hypoxia (IH) is extensively applied to challenge cardiovascular and respiratory function, and to induce physiological acclimatization. The purpose of this study was to test the hypothesis that oxyhemoglobin equilibrium and tachycardiac responses during hypoxemia were enhanced after 14-day IH exposures. Normobaric-poikilocapnic hypoxia was induced with inhalation of 10% O2 for 5-6 min interspersed with 4 min recovery on eight nonsmokers. Heart rate (HR), arterial O2 saturation (SaO 2), and end-tidal O2 (PetO 2) were continuously monitored during cyclic normoxia and hypoxia. These variables were compared during the first and fifth hypoxic bouts between day 1 and day 14. There was a rightward shift in the oxyhemoglobin equilibrium response following 14-day IH exposures, as indicated by the greater PetO 2 (an index of arterial Po2) at 50% of SaO 2 on day 14 compared with day 1 [33.9 ± 1.5 vs. 28.2 ± 1.3 mmHg (P = 0.005) during the first hypoxic bout and 39.4 ± 2.4 vs. 31.4 ± 1.5 mmHg (P = 0.006) during the fifth hypoxic bout] and by the augmented gains of ΔSaO 2/ΔPetO 2 (i.e., deoxygenation) during PetO 2 from 65 to 40 mmHg in the first (1.12 ± 0.08 vs. 0.80 ± 0.02%/mmHg, P = 0.001) and the fifth (1.76 ± 0.31 vs. 1.05 ± 0.06%/mmHg, P = 0.024) hypoxic bouts. Repetitive IH exposures attenuated (P = 0.049) the tachycardiac response to hypoxia while significantly enhancing normoxic R-R interval variability in low-frequency and high-frequency spectra without changes in arterial blood pressure at rest or during hypoxia. We conclude that 14-day IH exposures enhance arterial O2 delivery and improve vagal control of HR during hypoxic hypoxemia.
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Affiliation(s)
- Peizhen Zhang
- Department of Integrative Physiology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; Beijing Sport University, Beijing, China
| | - H Fred Downey
- Department of Integrative Physiology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; Cardiovascular Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; and
| | - Shande Chen
- Department of Biostatistics, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Xiangrong Shi
- Department of Integrative Physiology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; Cardiovascular Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; and
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Moraes DJA, Bonagamba LGH, Costa KM, Costa-Silva JH, Zoccal DB, Machado BH. Short-term sustained hypoxia induces changes in the coupling of sympathetic and respiratory activities in rats. J Physiol 2014; 592:2013-33. [PMID: 24614747 DOI: 10.1113/jphysiol.2013.262212] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Individuals experiencing sustained hypoxia (SH) exhibit adjustments in the respiratory and autonomic functions by neural mechanisms not yet elucidated. In the present study we evaluated the central mechanisms underpinning the SH-induced changes in the respiratory pattern and their impact on the sympathetic outflow. Using a decerebrated arterially perfused in situ preparation, we verified that juvenile rats exposed to SH (10% O2) for 24 h presented an active expiratory pattern, with increased abdominal, hypoglossal and vagal activities during late-expiration (late-E). SH also enhanced the activity of augmenting-expiratory neurones and depressed the activity of post-inspiratory neurones of the Bötzinger complex (BötC) by mechanisms not related to changes in their intrinsic electrophysiological properties. SH rats exhibited high thoracic sympathetic activity and arterial pressure levels associated with an augmented firing frequency of pre-sympathetic neurones of the rostral ventrolateral medulla (RVLM) during the late-E phase. The antagonism of ionotropic glutamatergic receptors in the BötC/RVLM abolished the late-E bursts in expiratory and sympathetic outputs of SH rats, indicating that glutamatergic inputs to the BötC/RVLM are essential for the changes in the expiratory and sympathetic coupling observed in SH rats. We also observed that the usually silent late-E neurones of the retrotrapezoid nucleus/parafacial respiratory group became active in SH rats, suggesting that this neuronal population may provide the excitatory drive essential to the emergence of active expiration and sympathetic overactivity. We conclude that short-term SH induces the activation of medullary expiratory neurones, which affects the pattern of expiratory motor activity and its coupling with sympathetic activity.
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Affiliation(s)
- Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil.
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Voituron N, Jeton F, Cholley Y, Hasnaoui-Saadani RE, Marchant D, Quidu P, Favret F, Richalet JP, Pichon A. Catalyzing role of erythropoietin on the nitric oxide central pathway during the ventilatory responses to hypoxia. Physiol Rep 2014; 2:e00223. [PMID: 24744892 PMCID: PMC3966246 DOI: 10.1002/phy2.223] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 01/09/2014] [Accepted: 01/11/2014] [Indexed: 02/03/2023] Open
Abstract
The N‐Methyl‐d‐Aspartate (NMDA) receptors – neuronal nitric oxide synthase (nNOS) pathway is involved in the ventilatory response to hypoxia. The objective was to assess the possible effect of erythropoietin deficiency and chronic exposure to hypoxia on this pathway during ventilatory response to acute hypoxia. Wild‐type (WT) and erythropoietin‐deficient (Epo‐TAgh) male mice were exposed (14 days) either to hypobaric hypoxia (Pb = 435 mmHg) or to normoxia. The ventilation was measured at 21% or 8% O2 after injection of vehicle (NaCl), nNOS inhibitor (SMTC) or NMDA receptor antagonist (MK‐801). Nitric oxide production and the expression of NMDA receptor and nNOS were assessed by real‐time RT‐PCR and Western blot analyses in the medulla. At rest, Epo‐TAgh mice displayed normal ventilatory parameters at 21% O2 but did not respond to acute hypoxia despite a larger expression of NMDA receptors and nNOS in the medulla. Ventilatory acclimatization to hypoxia was observed in WT but was absent in Epo‐TAgh mice. nNOS inhibition blunted the hypoxic ventilatory acclimatization of WT mice without any effect in Epo‐TAgh mice. Acute hypoxic ventilatory response (HVR) was increased after chronic hypoxia in WT but remained unchanged in Epo‐TAgh mice. Ventilatory response to acute hypoxia was modified by MK‐801 injection in WT and Epo‐TAgh mice. The results confirm that adequate erythropoietin level is necessary to obtain an appropriate HVR and a significant ventilatory acclimatization to hypoxia. Furthermore, erythropoietin plays a potential catalyzing role in the NMDA‐NO central pathway during the ventilatory response and acclimatization to hypoxia. e00223 Adequate erythropoietin level is necessary to obtain an appropriate hypoxic ventilatory response and a significant ventilatory acclimatization to hypoxia. Erythropoietin plays a potential catalyzing role on the N‐Methyl‐d‐Aspartate (NMDA)‐nNOS central pathway during the ventilatory response and acclimatization to hypoxia.
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Affiliation(s)
- Nicolas Voituron
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France ; Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité
| | - Florine Jeton
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France ; Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité
| | - Yannick Cholley
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France
| | - Raja El Hasnaoui-Saadani
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France
| | - Dominique Marchant
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France
| | - Patricia Quidu
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France
| | - Fabrice Favret
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France
| | - Jean-Paul Richalet
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France ; Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité
| | - Aurélien Pichon
- Laboratoire "Réponses cellulaires et fonctionnelles à l'hypoxie", Université Paris 13, Sorbonne Paris Cité, UFR SMBH, EA 2363, Bobigny, 93017, France ; Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité
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50
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Andreou G, Vlachos F, Makanikas K. Effects of chronic obstructive pulmonary disease and obstructive sleep apnea on cognitive functions: evidence for a common nature. SLEEP DISORDERS 2014; 2014:768210. [PMID: 24649370 PMCID: PMC3932644 DOI: 10.1155/2014/768210] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 10/09/2013] [Accepted: 10/31/2013] [Indexed: 12/16/2022]
Abstract
Patients with chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea syndrome (OSAS) show similar neurocognitive impairments. Effects are more apparent in severe cases, whereas in moderate and mild cases the effects are equivocal. The exact mechanism that causes cognitive dysfunctions in both diseases is still unknown and only suggestions have been made for each disease separately. The primary objective of this review is to present COPD and OSAS impact on cognitive functions. Secondly, it aims to examine the potential mechanisms by which COPD and OSAS can be linked and provide evidence for a common nature that affects cognitive functions in both diseases. Patients with COPD and OSAS compared to normal distribution show significant deficits in the cognitive abilities of attention, psychomotor speed, memory and learning, visuospatial and constructional abilities, executive skills, and language. The severity of these deficits in OSAS seems to correlate with the physiological events such as sleep defragmentation, apnea/hypopnea index, and hypoxemia, whereas cognitive impairments in COPD are associated with hypoventilation, hypoxemia, and hypercapnia. These factors as well as vascocerebral diseases and changes in systemic hemodynamic seem to act in an intermingling and synergistic way on the cause of cognitive dysfunctions in both diseases. However, low blood oxygen pressure seems to be the dominant factor that contributes to the presence of cognitive deficits in both COPD and OSAS.
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Affiliation(s)
- Georgia Andreou
- Department of Special Education, University of Thessaly, Argonafton & Filellinon, 38221 Volos, Greece
| | - Filippos Vlachos
- Department of Special Education, University of Thessaly, Argonafton & Filellinon, 38221 Volos, Greece
| | - Konstantinos Makanikas
- Department of Special Education, University of Thessaly, Argonafton & Filellinon, 38221 Volos, Greece
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