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Daher A, Payne S. The conducted vascular response as a mediator of hypercapnic cerebrovascular reactivity: A modelling study. Comput Biol Med 2024; 170:107985. [PMID: 38245966 DOI: 10.1016/j.compbiomed.2024.107985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/29/2023] [Accepted: 01/13/2024] [Indexed: 01/23/2024]
Abstract
It is well established that the cerebral blood flow (CBF) shows exquisite sensitivity to changes in the arterial blood partial pressure of CO2 ( [Formula: see text] ), which is reflected by an index termed cerebrovascular reactivity. In response to elevations in [Formula: see text] (hypercapnia), the vessels of the cerebral microvasculature dilate, thereby decreasing the vascular resistance and increasing CBF. Due to the challenges of access, scale and complexity encountered when studying the microvasculature, however, the mechanisms behind cerebrovascular reactivity are not fully understood. Experiments have previously established that the cholinergic release of the Acetylcholine (ACh) neurotransmitter in the cortex is a prerequisite for the hypercapnic response. It is also known that ACh functions as an endothelial-dependent agonist, in which the local administration of ACh elicits local hyperpolarization in the vascular wall; this hyperpolarization signal is then propagated upstream the vascular network through the endothelial layer and is coupled to a vasodilatory response in the vascular smooth muscle (VSM) layer in what is known as the conducted vascular response (CVR). Finally, experimental data indicate that the hypercapnic response is more strongly correlated with the CO2 levels in the tissue than in the arterioles. Accordingly, we hypothesize that the CVR, evoked by increases in local tissue CO2 levels and a subsequent local release of ACh, is responsible for the CBF increase observed in response to elevations in [Formula: see text] . By constructing physiologically grounded dynamic models of CBF and control in the cerebral vasculature, ones that integrate the available knowledge and experimental data, we build a new model of the series of signalling events and pathways underpinning the hypercapnic response, and use the model to provide compelling evidence that corroborates the aforementioned hypothesis. If the CVR indeed acts as a mediator of the hypercapnic response, the proposed mechanism would provide an important addition to our understanding of the repertoire of metabolic feedback mechanisms possessed by the brain and would motivate further in-vivo investigation. We also model the interaction of the hypercapnic response with dynamic cerebral autoregulation (dCA), the collection of mechanisms that the brain possesses to maintain near constant CBF despite perturbations in pressure, and show how the dCA mechanisms, which otherwise tend to be overlooked when analysing experimental results of cerebrovascular reactivity, could play a significant role in shaping the CBF response to elevations in [Formula: see text] . Such in-silico models can be used in tandem with in-vivo experiments to expand our understanding of cerebrovascular diseases, which continue to be among the leading causes of morbidity and mortality in humans.
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Affiliation(s)
- Ali Daher
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
| | - Stephen Payne
- Institute of Applied Mechanics, National Taiwan University, Taiwan
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Gałgańska H, Jarmuszkiewicz W, Gałgański Ł. Carbon dioxide and MAPK signalling: towards therapy for inflammation. Cell Commun Signal 2023; 21:280. [PMID: 37817178 PMCID: PMC10566067 DOI: 10.1186/s12964-023-01306-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 09/05/2023] [Indexed: 10/12/2023] Open
Abstract
Inflammation, although necessary to fight infections, becomes a threat when it exceeds the capability of the immune system to control it. In addition, inflammation is a cause and/or symptom of many different disorders, including metabolic, neurodegenerative, autoimmune and cardiovascular diseases. Comorbidities and advanced age are typical predictors of more severe cases of seasonal viral infection, with COVID-19 a clear example. The primary importance of mitogen-activated protein kinases (MAPKs) in the course of COVID-19 is evident in the mechanisms by which cells are infected with SARS-CoV-2; the cytokine storm that profoundly worsens a patient's condition; the pathogenesis of diseases, such as diabetes, obesity, and hypertension, that contribute to a worsened prognosis; and post-COVID-19 complications, such as brain fog and thrombosis. An increasing number of reports have revealed that MAPKs are regulated by carbon dioxide (CO2); hence, we reviewed the literature to identify associations between CO2 and MAPKs and possible therapeutic benefits resulting from the elevation of CO2 levels. CO2 regulates key processes leading to and resulting from inflammation, and the therapeutic effects of CO2 (or bicarbonate, HCO3-) have been documented in all of the abovementioned comorbidities and complications of COVID-19 in which MAPKs play roles. The overlapping MAPK and CO2 signalling pathways in the contexts of allergy, apoptosis and cell survival, pulmonary oedema (alveolar fluid resorption), and mechanical ventilation-induced responses in lungs and related to mitochondria are also discussed. Video Abstract.
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Affiliation(s)
- Hanna Gałgańska
- Faculty of Biology, Molecular Biology Techniques Laboratory, Adam Mickiewicz University in Poznan, Uniwersytetu Poznanskiego 6, 61-614, Poznan, Poland
| | - Wieslawa Jarmuszkiewicz
- Faculty of Biology, Department of Bioenergetics, Adam Mickiewicz University in Poznan, Institute of Molecular Biology and Biotechnology, Uniwersytetu Poznanskiego 6, 61-614, Poznan, Poland
| | - Łukasz Gałgański
- Faculty of Biology, Department of Bioenergetics, Adam Mickiewicz University in Poznan, Institute of Molecular Biology and Biotechnology, Uniwersytetu Poznanskiego 6, 61-614, Poznan, Poland.
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Martins Sá RW, Theparambil SM, Dos Santos KM, Christie IN, Marina N, Cardoso BV, Hosford PS, Antunes VR. Salt-loading promotes extracellular ATP release mediated by glial cells in the hypothalamic paraventricular nucleus of rats. Mol Cell Neurosci 2023; 124:103806. [PMID: 36592801 DOI: 10.1016/j.mcn.2022.103806] [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: 05/15/2022] [Revised: 12/21/2022] [Accepted: 12/28/2022] [Indexed: 01/01/2023] Open
Abstract
Previously, we have shown that purinergic signalling is involved in the control of hyperosmotic-induced sympathoexcitation at the level of the PVN, via activation of P2X receptors. However, the source(s) of ATP that drives osmotically-induced increases in sympathetic outflow remained undetermined. Here, we tested the two competing hypotheses that either (1) higher extracellular ATP in PVN during salt loading (SL) is a result of a failure of ectonucleotidases to metabolize ATP; and/or (2) SL can stimulate PVN astrocytes to release ATP. Rats were salt loaded with a 2 % NaCl solution replacing drinking water up to 4 days, an experimental model known to cause a gradual increase in blood pressure and plasma osmolarity. Immunohistochemical assessment of glial-fibrillary acidic protein (GFAP) revealed increased glial cell reactivity in the PVN of rats after 4 days of high salt exposure. ATP and adenosine release measurements via biosensors in hypothalamic slices showed that baseline ATP release was increased 17-fold in the PVN while adenosine remained unchanged. Disruption of Ca2+-dependent vesicular release mechanisms in PVN astrocytes by virally-driven expression of a dominant-negative SNARE protein decreased the release of ATP. The activity of ectonucleotidases quantified in vitro by production of adenosine from ATP was increased in SL group. Our results showed that SL stimulates the release of ATP in the PVN, at least in part, from glial cells by a vesicle-mediated route and likely contributes to the neural control of circulation during osmotic challenges.
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Affiliation(s)
- Renato W Martins Sá
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Shefeeq M Theparambil
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Karoline Martins Dos Santos
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Isabel N Christie
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Nephtali Marina
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Barbara V Cardoso
- Department of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Patrick S Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Vagner R Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
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Gourine AV, Dale N. Brain H + /CO 2 sensing and control by glial cells. Glia 2022; 70:1520-1535. [PMID: 35102601 DOI: 10.1002/glia.24152] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 01/11/2022] [Accepted: 01/17/2022] [Indexed: 01/04/2023]
Abstract
Maintenance of constant brain pH is critically important to support the activity of individual neurons, effective communication within the neuronal circuits, and, thus, efficient processing of information by the brain. This review article focuses on how glial cells detect and respond to changes in brain tissue pH and concentration of CO2 , and then trigger systemic and local adaptive mechanisms that ensure a stable milieu for the operation of brain circuits. We give a detailed account of the cellular and molecular mechanisms underlying sensitivity of glial cells to H+ and CO2 and discuss the role of glial chemosensitivity and signaling in operation of three key mechanisms that work in concert to keep the brain pH constant. We discuss evidence suggesting that astrocytes and marginal glial cells of the brainstem are critically important for central respiratory CO2 chemoreception-a fundamental physiological mechanism that regulates breathing in accord with changes in blood and brain pH and partial pressure of CO2 in order to maintain systemic pH homeostasis. We review evidence suggesting that astrocytes are also responsible for the maintenance of local brain tissue extracellular pH in conditions of variable acid loads associated with changes in the neuronal activity and metabolism, and discuss potential role of these glial cells in mediating the effects of CO2 on cerebral vasculature.
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Affiliation(s)
- Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry, UK
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Abstract
Breathing is a vital rhythmic motor behavior with a surprisingly broad influence on the brain and body. The apparent simplicity of breathing belies a complex neural control system, the breathing central pattern generator (bCPG), that exhibits diverse operational modes to regulate gas exchange and coordinate breathing with an array of behaviors. In this review, we focus on selected advances in our understanding of the bCPG. At the core of the bCPG is the preBötzinger complex (preBötC), which drives inspiratory rhythm via an unexpectedly sophisticated emergent mechanism. Synchronization dynamics underlying preBötC rhythmogenesis imbue the system with robustness and lability. These dynamics are modulated by inputs from throughout the brain and generate rhythmic, patterned activity that is widely distributed. The connectivity and an emerging literature support a link between breathing, emotion, and cognition that is becoming experimentally tractable. These advances bring great potential for elucidating function and dysfunction in breathing and other mammalian neural circuits.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
| | - Kaiwen Kam
- Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA
| | | | - Jack L Feldman
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
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Doi H, Horio T, Choi YJ, Takahashi K, Noda T, Sawada K. CMOS-Based Redox-Type Label-Free ATP Image Sensor for In Vitro Sensitive Imaging of Extracellular ATP. SENSORS (BASEL, SWITZERLAND) 2021; 22:75. [PMID: 35009624 PMCID: PMC8747181 DOI: 10.3390/s22010075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
Adenosine 5'-triphosphate (ATP) plays a crucial role as an extracellular signaling molecule in the central nervous system and is closely related to various nerve diseases. Therefore, label-free imaging of extracellular ATP dynamics and spatiotemporal analysis is crucial for understanding brain function. To decrease the limit of detection (LOD) of imaging extracellular ATP, we fabricated a redox-type label-free ATP image sensor by immobilizing glycerol-kinase (GK), L-α-glycerophosphate oxidase (LGOx), and horseradish peroxidase (HRP) enzymes in a polymer film on a gold electrode-modified potentiometric sensor array with a 37.3 µm-pitch. Hydrogen peroxide (H2O2) is generated through the enzymatic reactions from GK to LGOx in the presence of ATP and glycerol, and ATP can be detected as changes in its concentration using an electron mediator. Using this approach, the LOD for ATP was 2.8 µM with a sensitivity of 77 ± 3.8 mV/dec., under 10 mM working buffers at physiological pH, such as in in vitro experiments, and the LOD was great superior 100 times than that of the hydrogen ion detection-based image sensor. This redox-type ATP image sensor may be successfully applied for in vitro sensitive imaging of extracellular ATP dynamics in brain nerve tissue or cells.
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Gourine AV, Spyer KM. Geoff Burnstock, purinergic signalling, and chemosensory control of breathing. Auton Neurosci 2021; 235:102839. [PMID: 34198056 DOI: 10.1016/j.autneu.2021.102839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/11/2021] [Accepted: 06/20/2021] [Indexed: 12/14/2022]
Abstract
This article is the authors' contribution to the tribute issue in honour of Geoffrey Burnstock, the founder of this journal and the field of purinergic signalling. We give a brief account of the results of experimental studies which at the beginning received valuable input from Geoff, who both directly and indirectly influenced our research undertaken over the last two decades. Research into the mechanisms controlling breathing identified ATP as the common mediator of the central and peripheral chemosensory transduction. Studies of the sources and mechanisms of chemosensory ATP release in the CNS suggested that this signalling pathway is universally engaged in conditions of increased metabolic demand by brain glial cells - astrocytes. Astrocytes appear to function as versatile CNS metabolic sensors that detect changes in brain tissue pH, CO2, oxygen, and cerebral perfusion pressure. Experimental studies on various aspects of astrocyte biology generated data indicating that the function of these omnipresent glial cells and communication between astrocytes and neurons are governed by purinergic signalling, - first discovered by Geoff Burnstock in the 70's and researched through his entire scientific career.
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Affiliation(s)
- Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
| | - K Michael Spyer
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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Astrocytic contribution to glutamate-related central respiratory chemoreception in vertebrates. Respir Physiol Neurobiol 2021; 294:103744. [PMID: 34302992 DOI: 10.1016/j.resp.2021.103744] [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: 04/30/2021] [Revised: 07/01/2021] [Accepted: 07/18/2021] [Indexed: 12/24/2022]
Abstract
Central respiratory chemoreceptors play a key role in the respiratory homeostasis by sensing CO2 and H+ in brain and activating the respiratory neural network. This ability of specific brain regions to respond to acidosis and hypercapnia is based on neuronal and glial mechanisms. Several decades ago, glutamatergic transmission was proposed to be involved as a main mechanism in central chemoreception. However, a complete identification of mechanism has been elusive. At the rostral medulla, chemosensitive neurons of the retrotrapezoid nucleus (RTN) are glutamatergic and they are stimulated by ATP released by RTN astrocytes in response to hypercapnia. In addition, recent findings show that caudal medullary astrocytes in brainstem can also contribute as CO2 and H+ sensors that release D-serine and glutamate, both gliotransmitters able to activate the respiratory neural network. In this review, we describe the mammalian astrocytic glutamatergic contribution to the central respiratory chemoreception trying to trace in vertebrates the emergence of several components involved in this process.
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Katsuki S, Ikeda K, Onimaru H, Dohi K, Izumizaki M. Effects of acetylcholine on hypoglossal and C4 nerve activity in brainstem-spinal cord preparations from newborn rat. Respir Physiol Neurobiol 2021; 293:103737. [PMID: 34229065 DOI: 10.1016/j.resp.2021.103737] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 06/17/2021] [Accepted: 07/01/2021] [Indexed: 11/17/2022]
Abstract
Effects of acetylcholine (ACh) on respiratory activity have been an intriguing theme especially in relation to central chemoreception and the control of hypoglossal nerve activity. We studied the effects of ACh on hypoglossal and phrenic (C4) nerve activities and inspiratory and pre-inspiratory neurons in the rostral ventrolateral medulla in brainstem-spinal cord preparations from newborn rats. ACh application increased respiratory rhythm, decreased inspiratory hypoglossal and C4 nerve burst amplitude, and enhanced pre-inspiratory hypoglossal activity. ACh induced membrane depolarization of pre-inspiratory neurons that might be involved in facilitation of respiratory rhythm by ACh. Effects of ACh on hypoglossal and C4 nerve activity were partially reversed by a nicotinic receptor blocker, mecamylamine. Further application of a muscarinic receptor antagonist, oxybutynin, resulted in slight increase of hypoglossal (but not C4) burst amplitude. Thus, ACh induced different effects on hypoglossal and C4 nerve activity in the brainstem-spinal cord preparation.
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Affiliation(s)
- Shino Katsuki
- Department of Physiology, Showa University School of Medicine, Tokyo 142-8555, Japan; Department of Emergency, Disaster and Critical Care Medicine, Showa University, Tokyo 142-8555, Japan
| | - Keiko Ikeda
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
| | - Hiroshi Onimaru
- Department of Physiology, Showa University School of Medicine, Tokyo 142-8555, Japan.
| | - Kenji Dohi
- Department of Emergency, Disaster and Critical Care Medicine, Showa University, Tokyo 142-8555, Japan
| | - Masahiko Izumizaki
- Department of Physiology, Showa University School of Medicine, Tokyo 142-8555, Japan
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Moreira TS, Sobrinho CR, Falquetto B, Oliveira LM, Lima JD, Mulkey DK, Takakura AC. The retrotrapezoid nucleus and the neuromodulation of breathing. J Neurophysiol 2020; 125:699-719. [PMID: 33427575 DOI: 10.1152/jn.00497.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Breathing is regulated by a host of arousal and sleep-wake state-dependent neuromodulators to maintain respiratory homeostasis. Modulators such as acetylcholine, norepinephrine, histamine, serotonin (5-HT), adenosine triphosphate (ATP), substance P, somatostatin, bombesin, orexin, and leptin can serve complementary or off-setting functions depending on the target cell type and signaling mechanisms engaged. Abnormalities in any of these modulatory mechanisms can destabilize breathing, suggesting that modulatory mechanisms are not overly redundant but rather work in concert to maintain stable respiratory output. The present review focuses on the modulation of a specific cluster of neurons located in the ventral medullary surface, named retrotrapezoid nucleus, that are activated by changes in tissue CO2/H+ and regulate several aspects of breathing, including inspiration and active expiration.
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Affiliation(s)
- Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Cleyton R Sobrinho
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Barbara Falquetto
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Luiz M Oliveira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Janayna D Lima
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
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Czuryszkiewicz D, Maćkowiak A, Marcinkowska K, Borkowski A, Chrzanowski Ł, Pernak J. Herbicidal Ionic Liquids Containing the Acetylcholine Cation. Chempluschem 2020; 84:268-276. [PMID: 31950757 DOI: 10.1002/cplu.201800651] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/05/2019] [Indexed: 12/22/2022]
Abstract
This study presents a new group of herbicidal ionic liquids (HILs) based on a cation occurs commonly in nature-acetylcholine. The HILs were obtained with a high yield through ion exchange between acetylcholine chloride and potassium or sodium salts of selected acids with herbicidal activity. The results of the herbicidal activity measurement against common oilseed rape (Brassica napus L.) exceeded those of the commercial products. Spray solutions of the synthesized HILs revealed high surface activity and wetting properties which further manifested as higher herbicidal activity. The reduction of surface tension and low contact angles together with the specific action of acetylcholine allowed for better penetration of synthesized HILs into plant tissues. In addition, OECD 301F tests confirmed high mineralization of the HILs. The simple transformation of commercial herbicides into acetylcholine HILs proved to be a very effective method of increasing their activity, and constitutes an interesting solution to the problem of weed infestation with the use of a substance commonly found in nature.
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Affiliation(s)
- Daria Czuryszkiewicz
- Department of Chemical Technology, Poznan University of Technology, Berdychowo 4, Poznan, 60-965, Poland
| | - Adam Maćkowiak
- Department of Chemical Technology, Poznan University of Technology, Berdychowo 4, Poznan, 60-965, Poland
| | - Katarzyna Marcinkowska
- Institute of Plant Protection, National Research Institute, Węgorka 20, Poznan, 60-318, Poland
| | - Andrzej Borkowski
- Faculty of Geology, University of Warsaw, Żwirki i Wigury 93, Warsaw, 02-089, Poland
| | - Łukasz Chrzanowski
- Department of Chemical Technology, Poznan University of Technology, Berdychowo 4, Poznan, 60-965, Poland
| | - Juliusz Pernak
- Department of Chemical Technology, Poznan University of Technology, Berdychowo 4, Poznan, 60-965, Poland
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Clayson MS, Devereaux MEM, Pamenter ME. Neurokinin-1 receptor activation is sufficient to restore the hypercapnic ventilatory response in the Substance P-deficient naked mole-rat. Am J Physiol Regul Integr Comp Physiol 2020; 318:R712-R721. [PMID: 31967860 DOI: 10.1152/ajpregu.00251.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Naked mole-rats (NMRs) live in large colonies within densely populated underground burrows. Their collective respiration generates significant metabolic carbon dioxide (CO2) that diffuses slowly out of the burrow network, creating a hypercapnic environment. Currently, the physiological mechanisms that underlie the ability of NMRs to tolerate environmental hypercapnia are largely unknown. To address this, we used whole-body plethysmography and respirometry to elucidate the hypercapnic ventilatory and metabolic responses of awake, freely behaving NMRs to 0%-10% CO2. We found that NMRs have a blunted hypercapnic ventilatory response (HCVR): ventilation increased only in 10% CO2. Conversely, metabolism was unaffected by hypercapnia. NMRs are insensitive to cutaneous acid-based pain caused by modified substance P (SP)-mediated peripheral neurotransmission, and SP is also an important neuromodulator of ventilation. Therefore, we re-evaluated physiological responses to hypercapnia in NMRs after an intraperitoneal injection of exogenous substance P (2 mg/kg) or a long-lived isoform of substance P {[pGlu5-MePhe8-MeGly9]SP(5-11), DiMe-C7; 40-400 μg/kg}. We found that both drugs restored hypercapnia sensitivity and unmasked an HCVR in animals breathing 2%-10% CO2. Taken together, our findings indicate that NMRs are remarkably tolerant of hypercapnic environments and have a blunted HCVR; however, the signaling network architecture required for a "normal" HCVR is retained but endogenously inactive. This muting of chemosensitivity likely suits the ecophysiology of this species, which presumably experiences hypercapnia regularly in their underground niche.
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Affiliation(s)
- Maxwell S Clayson
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Matthew E Pamenter
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.,University of Ottawa Brain and Mind Research Institute, Ottawa, Ontario, Canada
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Developmental Nicotine Exposure Alters Synaptic Input to Hypoglossal Motoneurons and Is Associated with Altered Function of Upper Airway Muscles. eNeuro 2019; 6:ENEURO.0299-19.2019. [PMID: 31712219 PMCID: PMC6860987 DOI: 10.1523/eneuro.0299-19.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/03/2019] [Accepted: 10/13/2019] [Indexed: 11/21/2022] Open
Abstract
Nicotine exposure during the fetal and neonatal periods [developmental nicotine exposure (DNE)] is associated with ineffective upper airway protective reflexes in infants. This could be explained by desensitized chemoreceptors and/or mechanoreceptors, diminished neuromuscular transmission or altered synaptic transmission among central neurons, as each of these systems depend in part on cholinergic signaling through nicotinic AChRs (nAChRs). Here, we showed that DNE blunts the response of the genioglossus (GG) muscle to nasal airway occlusion in lightly anesthetized rat pups. The GG muscle helps keep the upper airway open and is innervated by hypoglossal motoneurons (XIIMNs). Experiments using the phrenic nerve-diaphragm preparation showed that DNE does not alter transmission across the neuromuscular junction. Accordingly, we used whole cell recordings from XIIMNs in brainstem slices to examine the influence of DNE on glutamatergic synaptic transmission under baseline conditions and in response to an acute nicotine challenge. DNE did not alter excitatory transmission under baseline conditions. Analysis of cumulative probability distributions revealed that acute nicotine challenge of P1–P2 preparations resulted in an increase in the frequency of nicotine-induced glutamatergic inputs to XIIMNs in both control and DNE. By contrast, P3–P5 DNE pups showed a decrease, rather than an increase in frequency. We suggest that this, together with previous studies showing that DNE is associated with a compensatory increase in inhibitory synaptic input to XIIMNs, leads to an excitatory-inhibitory imbalance. This imbalance may contribute to the blunting of airway protective reflexes observed in nicotine exposed animals and human infants.
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Lima JD, Sobrinho CR, Falquetto B, Santos LK, Takakura AC, Mulkey DK, Moreira TS. Cholinergic neurons in the pedunculopontine tegmental nucleus modulate breathing in rats by direct projections to the retrotrapezoid nucleus. J Physiol 2019; 597:1919-1934. [PMID: 30724347 DOI: 10.1113/jp277617] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 02/04/2019] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Cholinergic projections from the pedunculopontine tegmental nucleus (PPTg) to the retrotrapezoid nucleus (RTN) are considered to be important for sleep-wake state-dependent control of breathing. The RTN also receives cholinergic input from the postinspiratory complex. Stimulation of the PPTg increases respiratory output under control conditions but not when muscarinic receptors in the RTN are blocked. The data obtained in the present study support the possibility that arousal-dependent modulation of breathing involves recruitment of cholinergic projections from the PPTg to the RTN. ABSTRACT The pedunculopontine tegmental nucleus (PPTg) in the mesopontine region has important physiological functions, including breathing control. The PPTg contains a variety of cell types, including cholinergic neurons that project to the rostral aspect of the ventrolateral medulla. In addition, cholinergic signalling in the retrotrapezoid nucleus (RTN), a region that contains neurons that regulate breathing in response to changes in CO2 /H+ , has been shown to activate chemosensitive neurons and increase inspiratory activity. The present study aimed to identify the source of cholinergic input to the RTN and determine whether cholinergic signalling in this region influences baseline breathing or the ventilatory response to CO2 in conscious male Wistar rats. Retrograde tracer Fluoro-Gold injected into the RTN labelled a subset of cholinergic PPTg neurons that presumably project directly to the chemosensitive region of the RTN. In unrestrained awake rats, unilateral injection of the glutamate (10 mm/100 nL) in the PPTg decreased tidal volume (VT ) but otherwise increased respiratory rate (fR ) and net respiratory output as indicated by an increase in ventilation (VE ). All respiratory responses elicited by PPTg stimulation were blunted by prior injection of methyl-atropine (5 mm/50-75 nL) into the RTN. These results show that stimulation of the PPTg can increase respiratory activity in part by cholinergic activation of chemosensitive elements of the RTN. Based on previous evidence that cholinergic PPTg projections may simultaneously activate expiratory output from the pFRG, we speculate that cholinergic signalling at the level of RTN region could also be involved in breathing regulation.
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Affiliation(s)
- Janayna D Lima
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, SP, Brazil
| | - Cleyton R Sobrinho
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, SP, Brazil
| | - Barbara Falquetto
- Department of Pharmacology, University of São Paulo, São Paulo, SP, Brazil
| | - Leonardo K Santos
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, SP, Brazil
| | - Ana C Takakura
- Department of Pharmacology, University of São Paulo, São Paulo, SP, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Thiago S Moreira
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, SP, Brazil
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15
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Pisanski A, Pagliardini S. The parafacial respiratory group and the control of active expiration. Respir Physiol Neurobiol 2018; 265:153-160. [PMID: 29933053 DOI: 10.1016/j.resp.2018.06.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 06/11/2018] [Accepted: 06/18/2018] [Indexed: 11/16/2022]
Abstract
Breathing at rest is typically characterized by three phases: active inspiration, post-inspiration (or stage 1 expiration), and passive expiration (or stage 2 expiration). Breathing during periods of increased respiratory demand, on the other hand, engages active expiration through recruitment of abdominal muscles in order to increase ventilation. It is currently hypothesized that different phases of the respiratory rhythm are driven by three coupled oscillators: the preBötzinger Complex, driving inspiration, the parafacial respiratory group (pFRG), driving active expiration and the post-inspiratory Complex, driving post-inspiration. In this paper we review advances in the understanding of the pFRG and its role in the generation of active expiration across different developmental stages and vigilance states. Recent experiments suggest that the abdominal recruitment varies across development depending on the vigilance state, possibly following the maturation of the network responsible for the generation of active expiration and neuromodulatory systems that influence its activity. The activity of the pFRG is tonically inhibited by GABAergic inputs and strongly recruited by cholinergic systems. However, the sources of these modulatory inputs and the physiological conditions under which these mechanisms are used to recruit active expiration and increase ventilation need further investigation. Some evidence suggests that active expiration during hypercapnia is evoked through disinhibition, while during hypoxia it is elicited through activation of catecholaminergic C1 neurons. Finally, a discussion of experiments indicating that the pFRG is anatomically and functionally distinct from the adjacent and partially overlapping chemosensitive neurons of the retrotrapezoid nucleus is also presented.
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Affiliation(s)
- Annette Pisanski
- Department of Physiology, University of Alberta, Edmonton, AB, Canada; Women and Children's Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Silvia Pagliardini
- Department of Physiology, University of Alberta, Edmonton, AB, Canada; Women and Children's Research Institute, University of Alberta, Edmonton, AB, Canada; Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
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16
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Marina N, Turovsky E, Christie IN, Hosford PS, Hadjihambi A, Korsak A, Ang R, Mastitskaya S, Sheikhbahaei S, Theparambil SM, Gourine AV. Brain metabolic sensing and metabolic signaling at the level of an astrocyte. Glia 2018; 66:1185-1199. [PMID: 29274121 PMCID: PMC5947829 DOI: 10.1002/glia.23283] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/04/2017] [Accepted: 11/29/2017] [Indexed: 12/18/2022]
Abstract
Astrocytes support neuronal function by providing essential structural and nutritional support, neurotransmitter trafficking and recycling and may also contribute to brain information processing. In this article we review published results and report new data suggesting that astrocytes function as versatile metabolic sensors of central nervous system (CNS) milieu and play an important role in the maintenance of brain metabolic homeostasis. We discuss anatomical and functional features of astrocytes that allow them to detect and respond to changes in the brain parenchymal levels of metabolic substrates (oxygen and glucose), and metabolic waste products (carbon dioxide). We report data suggesting that astrocytes are also sensitive to circulating endocrine signals-hormones like ghrelin, glucagon-like peptide-1 and leptin, that have a major impact on the CNS mechanisms controlling food intake and energy balance. We discuss signaling mechanisms that mediate communication between astrocytes and neurons and consider how these mechanisms are recruited by astrocytes activated in response to various metabolic challenges. We review experimental data suggesting that astrocytes modulate the activities of the respiratory and autonomic neuronal networks that ensure adaptive changes in breathing and sympathetic drive in order to support the physiological and behavioral demands of the organism in ever-changing environmental conditions. Finally, we discuss evidence suggesting that altered astroglial function may contribute to the pathogenesis of disparate neurological, respiratory and cardiovascular disorders such as Rett syndrome and systemic arterial hypertension.
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Affiliation(s)
- Nephtali Marina
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
- Research Department of Metabolism and Experimental Therapeutics, Division of MedicineUniversity College LondonLondonWC1E 6JJUnited Kingdom
| | - Egor Turovsky
- Laboratory of Intracellular SignallingInstitute of Cell Biophysics, Russian Academy of SciencesPushchinoRussia
| | - Isabel N Christie
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Patrick S Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Anna Hadjihambi
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Alla Korsak
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Richard Ang
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Svetlana Mastitskaya
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Shahriar Sheikhbahaei
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Shefeeq M Theparambil
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
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17
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Korsak A, Sheikhbahaei S, Machhada A, Gourine AV, Huckstepp RTR. The Role Of Parafacial Neurons In The Control Of Breathing During Exercise. Sci Rep 2018; 8:400. [PMID: 29321559 PMCID: PMC5762684 DOI: 10.1038/s41598-017-17412-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/24/2017] [Indexed: 02/07/2023] Open
Abstract
Neuronal cell groups residing within the retrotrapezoid nucleus (RTN) and C1 area of the rostral ventrolateral medulla oblongata contribute to the maintenance of resting respiratory activity and arterial blood pressure, and play an important role in the development of cardiorespiratory responses to metabolic challenges (such as hypercapnia and hypoxia). In rats, acute silencing of neurons within the parafacial region which includes the RTN and the rostral aspect of the C1 circuit (pFRTN/C1), transduced to express HM4D (Gi-coupled) receptors, was found to dramatically reduce exercise capacity (by 60%), determined by an intensity controlled treadmill running test. In a model of simulated exercise (electrical stimulation of the sciatic or femoral nerve in urethane anaesthetised spontaneously breathing rats) silencing of the pFRTN/C1 neurons had no effect on cardiovascular changes, but significantly reduced the respiratory response during steady state exercise. These results identify a neuronal cell group in the lower brainstem which is critically important for the development of the respiratory response to exercise and, determines exercise capacity.
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Affiliation(s)
- Alla Korsak
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Shahriar Sheikhbahaei
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Asif Machhada
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom.
| | - Robert T R Huckstepp
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom. .,School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom.
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18
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Lee YN, Okumura K, Horio T, Iwata T, Takahashi K, Hattori T, Sawada K. A bio-image sensor for simultaneous detection of multi-neurotransmitters. Talanta 2017; 179:569-574. [PMID: 29310276 DOI: 10.1016/j.talanta.2017.11.058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/22/2017] [Accepted: 11/26/2017] [Indexed: 12/17/2022]
Abstract
We report here a new bio-image sensor for simultaneous detection of spatial and temporal distribution of multi-neurotransmitters. It consists of multiple enzyme-immobilized membranes on a 128 × 128 pixel array with read-out circuit. Apyrase and acetylcholinesterase (AChE), as selective elements, are used to recognize adenosine 5'-triphosphate (ATP) and acetylcholine (ACh), respectively. To enhance the spatial resolution, hydrogen ion (H+) diffusion barrier layers are deposited on top of the bio-image sensor and demonstrated their prevention capability. The results are used to design the space among enzyme-immobilized pixels and the null H+ sensor to minimize the undesired signal overlap by H+ diffusion. Using this bio-image sensor, we can obtain H+ diffusion-independent imaging of concentration gradients of ATP and ACh in real-time. The sensing characteristics, such as sensitivity and detection of limit, are determined experimentally. With the proposed bio-image sensor the possibility exists for customizable monitoring of the activities of various neurochemicals by using different kinds of proton-consuming or generating enzymes.
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Affiliation(s)
- You-Na Lee
- Electrical & Electronic Information Eng., Toyohashi University of Technology, Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan.
| | - Koichi Okumura
- Electrical & Electronic Information Eng., Toyohashi University of Technology, Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
| | - Tomoko Horio
- Electrical & Electronic Information Eng., Toyohashi University of Technology, Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
| | - Tatsuya Iwata
- Electrical & Electronic Information Eng., Toyohashi University of Technology, Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
| | - Kazuhiro Takahashi
- Electrical & Electronic Information Eng., Toyohashi University of Technology, Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
| | - Toshiaki Hattori
- Electrical & Electronic Information Eng., Toyohashi University of Technology, Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
| | - Kazuaki Sawada
- Electrical & Electronic Information Eng., Toyohashi University of Technology, Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
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19
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Gourine AV, Funk GD. On the existence of a central respiratory oxygen sensor. J Appl Physiol (1985) 2017; 123:1344-1349. [PMID: 28522760 DOI: 10.1152/japplphysiol.00194.2017] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/04/2017] [Accepted: 05/16/2017] [Indexed: 11/22/2022] Open
Abstract
A commonly held view that dominates both the scientific and educational literature is that in terrestrial mammals the central nervous system lacks a physiological hypoxia sensor capable of triggering increases in lung ventilation in response to decreases in Po2 of the brain parenchyma. Indeed, a normocapnic hypoxic ventilatory response has never been observed in humans following bilateral resection of the carotid bodies. In contrast, almost complete or partial recovery of the hypoxic ventilatory response after denervation/removal of the peripheral respiratory oxygen chemoreceptors has been demonstrated in many experimental animals when assessed in an awake state. In this essay we review the experimental evidence obtained using in vitro and in vivo animal models, results of human studies, and discuss potential mechanisms underlying the effects of CNS hypoxia on breathing. We consider experimental limitations and discuss potential reasons why the recovery of the hypoxic ventilatory response has not been observed in humans. We review recent experimental evidence suggesting that the lower brain stem contains functional oxygen sensitive elements capable of stimulating respiratory activity independently of peripheral chemoreceptor input.
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Affiliation(s)
- Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom; and
| | - Gregory D Funk
- Department of Physiology, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
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