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Conde SV, Sacramento JF, Zinno C, Mazzoni A, Micera S, Guarino MP. Bioelectronic modulation of carotid sinus nerve to treat type 2 diabetes: current knowledge and future perspectives. Front Neurosci 2024; 18:1378473. [PMID: 38646610 PMCID: PMC11026613 DOI: 10.3389/fnins.2024.1378473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 03/26/2024] [Indexed: 04/23/2024] Open
Abstract
Bioelectronic medicine are an emerging class of treatments aiming to modulate body nervous activity to correct pathological conditions and restore health. Recently, it was shown that the high frequency electrical neuromodulation of the carotid sinus nerve (CSN), a small branch of the glossopharyngeal nerve that connects the carotid body (CB) to the brain, restores metabolic function in type 2 diabetes (T2D) animal models highlighting its potential as a new therapeutic modality to treat metabolic diseases in humans. In this manuscript, we review the current knowledge supporting the use of neuromodulation of the CSN to treat T2D and discuss the future perspectives for its clinical application. Firstly, we review in a concise manner the role of CB chemoreceptors and of CSN in the pathogenesis of metabolic diseases. Secondly, we describe the findings supporting the potential therapeutic use of the neuromodulation of CSN to treat T2D, as well as the feasibility and reversibility of this approach. A third section is devoted to point up the advances in the neural decoding of CSN activity, in particular in metabolic disease states, that will allow the development of closed-loop approaches to deliver personalized and adjustable treatments with minimal side effects. And finally, we discuss the findings supporting the assessment of CB activity in metabolic disease patients to screen the individuals that will benefit therapeutically from this bioelectronic approach in the future.
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Affiliation(s)
- Silvia V. Conde
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Joana F. Sacramento
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Ciro Zinno
- The BioRobotics Institute Scuola Superiore Sant’Anna, Pontedera, Italy
| | - Alberto Mazzoni
- The BioRobotics Institute Scuola Superiore Sant’Anna, Pontedera, Italy
| | - Silvestro Micera
- The BioRobotics Institute Scuola Superiore Sant’Anna, Pontedera, Italy
| | - Maria P. Guarino
- ciTechCare, School of Health Sciences Polytechnic of Leiria, Leiria, Portugal
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SheikhBahaei S, Marina N, Rajani V, Kasparov S, Funk GD, Smith JC, Gourine AV. Contributions of carotid bodies, retrotrapezoid nucleus neurons and preBötzinger complex astrocytes to the CO 2 -sensitive drive for breathing. J Physiol 2024; 602:223-240. [PMID: 37742121 PMCID: PMC10841148 DOI: 10.1113/jp283534] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/06/2023] [Indexed: 09/25/2023] Open
Abstract
Current models of respiratory CO2 chemosensitivity are centred around the function of a specific population of neurons residing in the medullary retrotrapezoid nucleus (RTN). However, there is significant evidence suggesting that chemosensitive neurons exist in other brainstem areas, including the rhythm-generating region of the medulla oblongata - the preBötzinger complex (preBötC). There is also evidence that astrocytes, non-neuronal brain cells, contribute to central CO2 chemosensitivity. In this study, we reevaluated the relative contributions of the RTN neurons, the preBötC astrocytes, and the carotid body chemoreceptors in mediating the respiratory responses to CO2 in experimental animals (adult laboratory rats). To block astroglial signalling via exocytotic release of transmitters, preBötC astrocytes were targeted to express the tetanus toxin light chain (TeLC). Bilateral expression of TeLC in preBötC astrocytes was associated with ∼20% and ∼30% reduction of the respiratory response to CO2 in conscious and anaesthetized animals, respectively. Carotid body denervation reduced the CO2 respiratory response by ∼25%. Bilateral inhibition of RTN neurons transduced to express Gi-coupled designer receptors exclusively activated by designer drug (DREADDGi ) by application of clozapine-N-oxide reduced the CO2 response by ∼20% and ∼40% in conscious and anaesthetized rats, respectively. Combined blockade of astroglial signalling in the preBötC, inhibition of RTN neurons and carotid body denervation reduced the CO2 -induced respiratory response by ∼70%. These data further support the hypothesis that the CO2 -sensitive drive to breathe requires inputs from the peripheral chemoreceptors and several central chemoreceptor sites. At the preBötC level, astrocytes modulate the activity of the respiratory network in response to CO2 , either by relaying chemosensory information (i.e. they act as CO2 sensors) or by enhancing the preBötC network excitability to chemosensory inputs. KEY POINTS: This study reevaluated the roles played by the carotid bodies, neurons of the retrotrapezoid nucleus (RTN) and astrocytes of the preBötC in mediating the CO2 -sensitive drive to breathe. The data obtained show that disruption of preBötC astroglial signalling, blockade of inputs from the peripheral chemoreceptors or inhibition of RTN neurons similarly reduce the respiratory response to hypercapnia. These data provide further support for the hypothesis that the CO2 -sensitive drive to breathe is mediated by the inputs from the peripheral chemoreceptors and several central chemoreceptor sites.
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Affiliation(s)
- Shahriar SheikhBahaei
- Centre for Cardiovascular and Metabolic Neuroscience, Research Department of Neuroscience Physiology and Pharmacology, University College London, London WC1E 6BT, UK
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, 20892 MD, USA
- present address: Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, 20892 MD, USA
| | - Nephtali Marina
- Centre for Cardiovascular and Metabolic Neuroscience, Research Department of Neuroscience Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Vishaal Rajani
- Department of Physiology, Neuroscience & Mental Health Institute, Women and Children’s Health Research Institute, University of Alberta, T6G 2E1, Canada
- present address: Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1B 3V6, Canada
| | - Sergey Kasparov
- Department of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | - Gregory D. Funk
- Department of Physiology, Neuroscience & Mental Health Institute, Women and Children’s Health Research Institute, University of Alberta, T6G 2E1, Canada
| | - Jeffrey C. Smith
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, 20892 MD, USA
| | - Alexander V. Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Research Department of Neuroscience Physiology and Pharmacology, University College London, London WC1E 6BT, UK
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Bhandare AM, Dale N. Neural correlate of reduced respiratory chemosensitivity during chronic epilepsy. Front Cell Neurosci 2023; 17:1288600. [PMID: 38193031 PMCID: PMC10773801 DOI: 10.3389/fncel.2023.1288600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 11/27/2023] [Indexed: 01/10/2024] Open
Abstract
While central autonomic, cardiac, and/or respiratory dysfunction underlies sudden unexpected death in epilepsy (SUDEP), the specific neural mechanisms that lead to SUDEP remain to be determined. In this study, we took advantage of single-cell neuronal Ca2+ imaging and intrahippocampal kainic acid (KA)-induced chronic epilepsy in mice to investigate progressive changes in key cardiorespiratory brainstem circuits during chronic epilepsy. Weeks after induction of status epilepticus (SE), when mice were experiencing recurrent spontaneous seizures (chronic epilepsy), we observed that the adaptive ventilatory responses to hypercapnia were reduced for 5 weeks after SE induction with its partial recovery at week 7. These changes were paralleled by alterations in the chemosensory responses of neurons in the retrotrapezoid nucleus (RTN). Neurons that displayed adapting responses to hypercapnia were less prevalent and exhibited smaller responses over weeks 3-5, whereas neurons that displayed graded responses to hypercapnia became more prevalent by week 7. Over the same period, chemosensory responses of the presympathetic rostral ventrolateral medullary (RVLM) neurons showed no change. Mice with chronic epilepsy showed enhanced sensitivity to seizures, which invade the RTN and possibly put the chemosensory circuits at further risk of impairment. Our findings establish a dysfunctional breathing phenotype with its RTN neuronal correlate in mice with chronic epilepsy and suggest that the assessment of respiratory chemosensitivity may have the potential for identifying people at risk of SUDEP.
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Affiliation(s)
- Amol M. Bhandare
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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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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Guluzade NA, Huggard JD, Duffin J, Keir DA. A test of the interaction between central and peripheral respiratory chemoreflexes in humans. J Physiol 2023; 601:4591-4609. [PMID: 37566804 DOI: 10.1113/jp284772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic CO2 tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Twenty participants (10F) completed three repetitions of modified rebreathing tests with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) clamped at 150, 70, 60 and 45 mmHg. End-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ),P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , ventilation (V ̇ $\dot{V}$ E ) and calculated oxygen saturation (SC O2 ) were measured breath-by-breath by gas-analyser and pneumotach. TheV ̇ $\dot{V}$ E -P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship of repeat-trials were linear-interpolated, combined, averaged into 1 mmHg bins, and fitted with a double-linear function (V ̇ $\dot{V}$ E S, L min-1 mmHg-1 ). PChS was computed at intervals of 1 mmHg ofP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding SC O2 ; and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). These processing steps were repeated at eachP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ to produce the PChS vs. isocapnicP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship. These were fitted with linear and polynomial functions, and Akaike information criterion identified the best-fit model. One-way repeated measures analysis of variance assessed between-condition differences.V ̇ $\dot{V}$ E S increased (P < 0.0001) with isoxicP ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ from 3.7 ± 1.5 L min-1 mmHg-1 at 150 mmHg to 4.4 ± 1.8, 5.0 ± 1.6 and 6.0 ± 2.2 Lmin-1 mmHg-1 at 70, 60 and 45 mmHg, respectively. Mean SC O2 fell progressively (99.3 ± 0%, 93.7 ± 0.1%, 90.4 ± 0.1% and 80.5 ± 0.1%; P < 0.0001). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear model in 75%. Despite increasing central chemoreflex activation, PChS increased linearly withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ indicative of an additive central-peripheral chemoreflex response. KEY POINTS: How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Participants performed three repetitions of modified rebreathing with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ fixed at 150, 70, 60 and 45 mmHg. PChS was computed at intervals of 1 mmHg of end-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding calculated oxygen saturation (SC O2 ); and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear (rather than polynomial) model in 15 of 20. Most participants did not exhibit a hypo- or hyper-additive effect of central chemoreceptors on the peripheral chemoreflex indicating that the interaction was additive.
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Affiliation(s)
- Nasimi A Guluzade
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Joshua D Huggard
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Thornhill Research Inc., Toronto, ON, Canada
| | - Daniel A Keir
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, ON, Canada
- Lawson Health Research Institute, London, ON, Canada
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Dempsey JA, Gibbons TD. Rethinking O 2 , CO 2 and breathing during wakefulness and sleep. J Physiol 2023. [PMID: 37750243 DOI: 10.1113/jp284551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 09/11/2023] [Indexed: 09/27/2023] Open
Abstract
We have examined the importance of three long-standing questions concerning chemoreceptor influences on cardiorespiratory function which are currently experiencing a resurgence of study among physiologists and clinical investigators. Firstly, while carotid chemoreceptors (CB) are required for hypoxic stimulation of breathing, use of an isolated, extracorporeally perfused CB preparation in unanaesthetized animals with maintained tonic input from the CB, reveals that extra-CB hypoxaemia also provides dose-dependent ventilatory stimulation sufficient to account for 40-50% of the total ventilatory response to steady-state hypoxaemia. Extra-CB hyperoxia also provides a dose- and time-dependent hyperventilation. Extra-CB sites of O2 -driven ventilatory stimulation identified to date include the medulla, kidney and spinal cord. Secondly, using the isolated or denervated CB preparation in awake animals and humans has demonstrated a hyperadditive effect of CB sensory input on central CO2 sensitivity, so that tonic CB activity accounts for as much as 35-40% of the normal, air-breathing eupnoeic drive to breathe. Thirdly, we argue for a key role for CO2 chemoreception and the neural drive to breathe in the pathogenesis of upper airway obstruction during sleep (OSA), based on the following evidence: (1) removal of the wakefulness drive to breathe enhances the effects of transient CO2 changes on breathing instability; (2) oscillations in respiratory motor output precipitate pharyngeal obstruction in sleeping subjects with compliant, collapsible airways; and (3) in the majority of patients in a large OSA cohort, a reduced neural drive to breathe accompanied reductions in both airflow and pharyngeal airway muscle dilator activity, precipitating airway obstruction.
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Affiliation(s)
| | - Travis D Gibbons
- University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
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Tubek S, Niewinski P, Langner-Hetmanczuk A, Jura M, Kuliczkowski W, Reczuch K, Ponikowski P. The effects of P2Y 12 adenosine receptors' inhibitors on central and peripheral chemoreflexes. Front Physiol 2023; 14:1214893. [PMID: 37538377 PMCID: PMC10394699 DOI: 10.3389/fphys.2023.1214893] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/30/2023] [Indexed: 08/05/2023] Open
Abstract
Introduction: The most common side effect of ticagrelor is dyspnea, which leads to premature withdrawal of this life-saving medication in 6.5% of patients. Increased chemoreceptors' sensitivity was suggested as a possible pathophysiological explanation of this phenomenon; however, the link between oversensitization of peripheral and/or central chemosensory areas and ticagrelor intake has not been conclusively proved. Methods: We measured peripheral chemoreceptors' sensitivity using hypoxic ventilatory response (HVR), central chemoreceptors' sensitivity using hypercapnic hyperoxic ventilatory response (HCVR), and dyspnea severity before and 4 ± 1 weeks following ticagrelor initiation in 11 subjects with chronic coronary syndrome undergoing percutaneous coronary intervention (PCI). The same tests were performed in 11 age-, sex-, and BMI-matched patients treated with clopidogrel. The study is registered at ClinicalTrials.com at NCT05080478. Results: Ticagrelor significantly increased both HVR (0.52 ± 0.46 vs. 0.84 ± 0.69 L min-1 %-1; p < 0.01) and HCVR (1.05 ± 0.64 vs. 1.75 ± 1.04 L min-1 mmHg-1; p < 0.01). The absolute change in HVR correlated with the change in HCVR. Clopidogrel administration did not significantly influence HVR (0.63 ± 0.32 vs. 0.58 ± 0.33 L min-1%-1; p = 0.53) and HCVR (1.22 ± 0.67 vs. 1.2 ± 0.64 L min-1 mmHg-1; p = 0.79). Drug-related dyspnea was reported by three subjects in the ticagrelor group and by none in the clopidogrel group. These patients were characterized by either high baseline HVR and HCVR or excessive increase in HVR following ticagrelor initiation. Discussion: Ticagrelor, contrary to clopidogrel, sensitizes both peripheral and central facets of chemodetection. Two potential mechanisms of ticagrelor-induced dyspnea have been identified: 1) high baseline HVR and HCVR or 2) excessive increase in HVR or HVR and HCVR. Whether other patterns of changes in chemosensitivities play a role in the pathogenesis of this phenomenon needs to be further investigated.
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Affiliation(s)
- Stanislaw Tubek
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
| | - Piotr Niewinski
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
| | - Anna Langner-Hetmanczuk
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
| | - Maksym Jura
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
- Department of Physiology, Wroclaw Medical University, Wroclaw, Poland
| | - Wiktor Kuliczkowski
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
| | - Krzysztof Reczuch
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
| | - Piotr Ponikowski
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
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Thakkar P, Pauza AG, Murphy D, Paton JFR. Carotid body: an emerging target for cardiometabolic co-morbidities. Exp Physiol 2023; 108:661-671. [PMID: 36999224 PMCID: PMC10988524 DOI: 10.1113/ep090090] [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: 10/04/2021] [Accepted: 03/03/2023] [Indexed: 04/01/2023]
Abstract
NEW FINDINGS What is the topic of this review? Regarding the global metabolic syndrome crisis, this review focuses on common mechanisms for high blood sugar and high blood pressure. Connections are made between the homeostatic regulation of blood pressure and blood sugar and their dysregulation to reveal signalling mechanisms converging on the carotid body. What advances does it highlight? The carotid body plays a major part in the generation of excessive sympathetic activity in diabetes and also underpins diabetic hypertension. As treatment of diabetic hypertension is notoriously difficult, we propose that novel receptors within the carotid body may provide a novel treatment strategy. ABSTRACT The maintenance of glucose homeostasis is obligatory for health and survival. It relies on peripheral glucose sensing and signalling between the brain and peripheral organs via hormonal and neural responses that restore euglycaemia. Failure of these mechanisms causes hyperglycaemia or diabetes. Current anti-diabetic medications control blood glucose but many patients remain with hyperglycemic condition. Diabetes is often associated with hypertension; the latter is more difficult to control in hyperglycaemic conditions. We ask whether a better understanding of the regulatory mechanisms of glucose control could improve treatment of both diabetes and hypertension when they co-exist. With the involvement of the carotid body (CB) in glucose sensing, metabolic regulation and control of sympathetic nerve activity, we consider the CB as a potential treatment target for both diabetes and hypertension. We provide an update on the role of the CB in glucose sensing and glucose homeostasis. Physiologically, hypoglycaemia stimulates the release of hormones such as glucagon and adrenaline, which mobilize or synthesize glucose; however, these counter-regulatory responses were markedly attenuated after denervation of the CBs in animals. Also, CB denervation prevents and reverses insulin resistance and glucose intolerance. We discuss the CB as a metabolic regulator (not just a sensor of blood gases) and consider recent evidence of novel 'metabolic' receptors within the CB and putative signalling peptides that may control glucose homeostasis via modulation of the sympathetic nervous system. The evidence presented may inform future clinical strategies in the treatment of patients with both diabetes and hypertension, which may include the CB.
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Affiliation(s)
- Pratik Thakkar
- Manaaki Manawa – the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Audrys G. Pauza
- Manaaki Manawa – the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Bristol Medical School: Translational Health SciencesUniversity of BristolBristolUK
| | - Julian F. R. Paton
- Manaaki Manawa – the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
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Chen S, Xu J, Gu G, Zhang Y, Zhang J, Zheng Y, Huang Y. Perioperative blood pressure and heart rate alterations after carotid body tumor excision: a retrospective study of 108 cases. BMC Anesthesiol 2022; 22:374. [PMID: 36463127 PMCID: PMC9719143 DOI: 10.1186/s12871-022-01917-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 11/18/2022] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Arising from chemoreceptor cells, carotid body tumors (CBTs) are rare neoplasms associated with hemodynamics. Perioperative changes in blood pressure (BP) and heart rate (HR) are not completely understood. METHODS This retrospective, observational, controlled study included all CBT patients from 2013 to 2018 in Peking Union Medical College Hospital. Perioperative changes in BP/HR within or between unilateral/bilateral/control groups were investigated. Perioperative details across Shamblin types were also assessed. RESULTS This study included 108 patients (116 excised CBTs). The postoperative systolic BP and HR increased in both unilateral (mean difference of systolic BP = 5.9mmHg, 95% CI 3.1 ~ 8.6; mean difference of HR = 3.7 bpm, 95% CI 2.6 ~ 4.9) and bilateral (mean difference of systolic BP = 10.3mmHg, 95% CI 0.6 ~ 19.9; mean difference of HR = 8.4 bpm, 95% CI 0.5 ~ 16.2) CBT patients compared with the preoperative measures. Compared with control group, the postoperative systolic BP increased (difference in the alteration = 6.3mmHg, 95% CI 3.5 ~ 9.0) in unilateral CBT patients; both systolic BP (difference in the alteration = 9.2mmHg, 95% CI 1.1 ~ 17.3) and HR (difference in the alteration = 5.3 bpm, 95% CI 1.0 ~ 9.6) increased in bilateral CBT patients. More CBT patients required extra antihypertensive therapy after surgery than controls (OR = 2.5, 95% CI 1.14 ~ 5.5). Maximum tumor diameter, intraoperative vascular injury, continuous vasoactive agent requirement, total fluid volume, transfusion, estimated blood loss, operation duration, postoperative pathology, overall complications, and intensive care unit/hospital lengths of stay significantly varied among Shamblin types. CONCLUSION CBT excision may be associated with subtle perioperative hemodynamic changes. Perioperative management of CBT patients necessitates careful assessment, full preparation and close postoperative monitoring.
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Affiliation(s)
- Si Chen
- grid.506261.60000 0001 0706 7839Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, 100730 Beijing, China ,grid.506261.60000 0001 0706 7839State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, 100730 Beijing, China
| | - Jingjing Xu
- grid.506261.60000 0001 0706 7839Department of Vascular Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Dongcheng District, 100730 Beijing, China ,grid.12527.330000 0001 0662 3178School of Medicine, Tsinghua University, 100084 Beijing, China
| | - Guangchao Gu
- grid.506261.60000 0001 0706 7839State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, 100730 Beijing, China ,grid.506261.60000 0001 0706 7839Department of Vascular Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Dongcheng District, 100730 Beijing, China
| | - Yuelun Zhang
- grid.506261.60000 0001 0706 7839Medical Research Center, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, 100730 Beijing, China
| | - Jiao Zhang
- grid.506261.60000 0001 0706 7839Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, 100730 Beijing, China
| | - Yuehong Zheng
- grid.506261.60000 0001 0706 7839State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, 100730 Beijing, China ,grid.506261.60000 0001 0706 7839Department of Vascular Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Dongcheng District, 100730 Beijing, China
| | - Yuguang Huang
- grid.506261.60000 0001 0706 7839Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, 100730 Beijing, China
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van der Schrier R, van Velzen M, Roozekrans M, Sarton E, Olofsen E, Niesters M, Smulders C, Dahan A. Carbon dioxide tolerability and toxicity in rat and man: A translational study. FRONTIERS IN TOXICOLOGY 2022; 4:1001709. [PMID: 36310693 PMCID: PMC9606673 DOI: 10.3389/ftox.2022.1001709] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 09/12/2022] [Indexed: 11/07/2022] Open
Abstract
Background: Due the increasing need for storage of carbon dioxide (CO2) more individuals are prone to be exposed to high concentrations of CO2 accidentally released into atmosphere, with deleterious consequences. Methods: We tested the effect of increasing CO2 concentrations in humans (6–12%) and rats (10–50%) at varying inhalation times (10–60 min). In humans, a continuous positive airway pressure helmet was used to deliver the gas mixture to the participants. Unrestrained rats were exposed to CO2 in a transparent chamber. In both species regular arterial blood gas samples were obtained. After the studies, the lungs of the animals were examined for macroscopic and microscopic abnormalities. Results: In humans, CO2 concentrations of 9% inhaled for >10 min, and higher concentrations inhaled for <10 min were poorly or not tolerated due to exhaustion, anxiety, dissociation or acidosis (pH < 7.2), despite intact oxygenation. In rats, concentrations of 30% and higher were associated with CO2 narcosis, epilepsy, poor oxygenation and, at 50% CO2, spontaneous death. Lung hemorrhage and edema were observed in the rats at inhaled concentrations of 30% and higher. Conclusion: This study provides essential insight into the occurrence of physiological changes in humans and fatalities in rats after acute exposure to high levels of CO2. Humans tolerate 9% CO2 and retain their ability to function coherently for up to 10 min. These data support reconsideration of the current CO2 levels (<7.5%) that pose a risk to exposed individuals (<7.5%) as determined by governmental agencies to ≤9%.
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Affiliation(s)
| | - Monique van Velzen
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Margot Roozekrans
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands,Department of Anesthesiology, Noordwest Ziekenhuisgroep, Alkmaar, Netherlands
| | - Elise Sarton
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Erik Olofsen
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Marieke Niesters
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | | | - Albert Dahan
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands,*Correspondence: Albert Dahan,
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11
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Gibbons TD, Dempsey JA, Thomas KN, Campbell HA, Stothers TAM, Wilson LC, Ainslie PN, Cotter JD. Contribution of the carotid body to thermally mediated hyperventilation in humans. J Physiol 2022; 600:3603-3624. [PMID: 35731687 DOI: 10.1113/jp282918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 06/15/2022] [Indexed: 01/05/2023] Open
Abstract
Humans hyperventilate under heat and cold strain. This hyperventilatory response has detrimental consequences including acid-base dysregulation, dyspnoea, decreased cerebral blood flow and accelerated brain heating. The ventilatory response to hypoxia is exaggerated under whole-body heating and cooling, indicating that altered carotid body function might contribute to thermally mediated hyperventilation. To address whether the carotid body might contribute to heat- and cold-induced hyperventilation, we indirectly measured carotid body tonic activity via hyperoxia, and carotid body sensitivity via hypoxia, under graded heat and cold strain in 13 healthy participants in a repeated-measures design. We hypothesised that carotid body tonic activity and sensitivity would be elevated in a dose-dependent manner under graded heat and cold strain, thereby supporting its role in driving thermally mediated hyperventilation. Carotid body tonic activity was increased in a dose-dependent manner with heating, reaching 175% above baseline (P < 0.0005), and carotid body suppression with hyperoxia removed all of the heat-induced increase in ventilation (P = 0.9297). Core cooling increased carotid body activity by up to 250% (P < 0.0001), but maximal values were reached with mild cooling and thereafter plateaued. Carotid body sensitivity to hypoxia was profoundly increased by up to 180% with heat stress (P = 0.0097), whereas cooling had no detectable effect on hypoxic sensitivity. In summary, cold stress increased carotid body tonic activity and this effect was saturated with mild cooling, whereas heating had clear dose-dependent effects on carotid body tonic activity and sensitivity. These dose-dependent effects with heat strain indicate that the carotid body probably plays a primary role in driving heat-induced hyperventilation. KEY POINTS: Humans over-breathe (hyperventilate) when under heat and cold stress, and though this has detrimental physiological repercussions, the mechanisms underlying this response are unknown. The carotid body, a small organ that is responsible for driving hyperventilation in hypoxia, was assessed under incremental heat and cold strain. The carotid body drive to breathe, as indirectly assessed by transient hyperoxia, increased in a dose-dependent manner with heating, reaching 175% above baseline; cold stress similarly increased the carotid body drive to breathe, but did not show dose-dependency. Carotid body sensitivity, as indirectly assessed by hypoxic ventilatory responses, was profoundly increased by 70-180% with mild and severe heat strain, whereas cooling had no detectable effect. Carotid body hyperactivity and hypersensitivity are two interrelated mechanisms that probably underlie the increased drive to breathe with heat strain, whereas carotid body hyperactivity during mild cooling may play a subsidiary role in cold-induced hyperventilation.
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Affiliation(s)
- Travis D Gibbons
- School of Physical Education, Sport & Exercise Science, University of Otago, Dunedin, Otago, New Zealand.,Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Jerome A Dempsey
- John Rankin Laboratory for Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Kate N Thomas
- Department of Surgical Sciences, University of Otago, Dunedin, Otago, New Zealand
| | - Holly A Campbell
- Department of Surgical Sciences, University of Otago, Dunedin, Otago, New Zealand
| | - Tiarna A M Stothers
- School of Physical Education, Sport & Exercise Science, University of Otago, Dunedin, Otago, New Zealand
| | - Luke C Wilson
- Department of Medicine, University of Otago, Dunedin, Otago, New Zealand
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - James D Cotter
- School of Physical Education, Sport & Exercise Science, University of Otago, Dunedin, Otago, New Zealand
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12
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Algera H, van der Schrier R, Cavalla D, van Velzen M, Roozekrans M, McMorn A, Snape M, Horrigan JP, Evans S, Kiernan B, Sarton E, Olofsen E, Niesters M, Dahan A. Respiratory effects of the atypical tricyclic antidepressant tianeptine in human models of opioid-induced respiratory depression. Anesthesiology 2022; 137:446-458. [PMID: 35867853 DOI: 10.1097/aln.0000000000004324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Animal data suggest that the antidepressant and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor modulator tianeptine is able to prevent opioid-induced respiratory depression. We hypothesize that oral or intravenous tianeptine can effectively prevent or counteract opioid-induced respiratory depression in humans. METHODS Healthy male and female volunteers participated in two studies that had a randomized, double blind, placebo-controlled, crossover design. We first tested oral tianeptine (37.5, 50 and 100 mg, 8 subjects/group) pretreatment followed by induction of alfentanil-induced respiratory depression (alfentanil target concentration 100 ng/mL). Primary endpoint was ventilation at an extrapolated end-tidal carbon dioxide concentration of 55 mmHg (V̇E55). We next determined the ability of four subsequent and increasing infusions of intravenous tianeptine (target tianeptine plasma concentrations 400, 1,000, 1,500 and 2,000 ng/mL, each given over 15 min), to counteract remifentanil-induced respiratory depression in 15 volunteers. Ventilation was measured at isohypercpania (baseline ventilation 20 ± 2 L/min). Primary endpoint was minute ventilation during the 60 min of tianeptine versus placebo infusion. RESULTS Alfentanil reduced V̇E55 to 13.7 (95% CI 8.6-18.8) L/min following placebo pretreatment and to 17.9 (10.2-25.7) L/min following 50 mg tianeptine pretreatment (mean difference between treatments 4.2 (-11.5-3.0) L/min, p = 0.070). Intravenous tianeptine in the measured concentration range of 500 to 2,000 ng/ml did not stimulate ventilation but instead worsened remifentanil-induced respiratory depression: tianeptine 9.6 ± 0.8 L/min versus placebo 15.0 ± 0.9 L/min, mean difference 5.3 L/min, 95% CI 2.5-8.2 L/min; p = 0.001, after 1 hour of treatment. CONCLUSIONS Neither oral nor intravenous tianeptine were respiratory stimulants. Intravenous tianeptine over the concentration range of 500-2000 ng/mL worsened respiratory depression induced by remifentanil.
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Affiliation(s)
- Hyke Algera
- Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands
| | | | | | - Monique van Velzen
- Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Margot Roozekrans
- Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands.,Department of Anesthesiology, Noordwest Ziekenhuisgroep, location Alkmaar, Alkmaar, the Netherlands
| | | | | | | | | | | | - Elise Sarton
- Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Erik Olofsen
- Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Marieke Niesters
- Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Albert Dahan
- Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands.,PainLess Foundation, Leiden, the Netherlands
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13
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Sakuma T, Shinomiya S, Takahara Y, Mizuno S. Awake Hypercapnic Ventilatory Response in Obstructive Sleep Apnea Syndrome. SLEEP MEDICINE RESEARCH 2022. [DOI: 10.17241/smr.2021.01172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background and Objective Decreased ventilatory response to carbon dioxide or hypercapnic ventilatory response (HCVR) is a feature of pediatric obstructive sleep apnea (OSA) and is also known to diminish during sleep in obese adolescents (age, 12–16 years) with OSA. It reduces minute ventilation, air flow, and tidal volume during inspiration, as well as upper airway obstruction. The purpose of this study was to investigate awake HCVR in adult patients with OSA and to elucidate its association with sleep apnea.Methods HCVR was measured before performing polysomnography (PSG). PSG is performed as the evaluation method during sleep, and the severity of apnea is evaluated by apnea hypopnea index. Patient background, PSG data and HCVR were examined.Results Awake HCVR was greater in patients with severe OSA than in patients with mild and moderate OSA, and in severe OSA patients, the HCVR during awaking was higher in patients with larger changes in saturation of percutaneous oxygen during sleep. Awake HCVR did not differ by age, but it was greater in morbidly obese patients with OSA than in thin patients with OSA. The most frequent apnea pattern of OSA was obstructive, regardless of severity; although with an increasing severity of OSA, the central pattern decreased and the mixed pattern increased in frequency. The appearance of the mixed pattern increased in the augmented HCVR group.Conclusions This study suggested that awake HCVR could be used as an index of progression and a factor to determine the effects of treatment in patients with OSA.
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14
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Milloy KM, White MG, Chicilo JOC, Cummings KJ, Pfoh JR, Day TA. Assessing central and peripheral respiratory chemoreceptor interaction in humans. Exp Physiol 2022; 107:1081-1093. [PMID: 35766127 DOI: 10.1113/ep089983] [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: 08/14/2021] [Accepted: 06/16/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? We investigated the interaction between central and peripheral respiratory chemoreceptors in healthy, awake human participants by (a) using a background of step increases in steady-state normoxic fraction of inspired carbon dioxide to alter central chemoreceptor activation and (b) using the transient hypoxia test to target the peripheral chemoreceptors. What is the main finding and its importance? Our data suggests that the central-peripheral respiratory chemoreceptor interaction is additive in minute ventilation and respiratory rate, but hypoadditive in tidal volume. Our study adds important new data in reconciling chemoreceptor interaction in awake healthy humans, and is consistent with previous reports of simple addition in intact rodents and humans. ABSTRACT Arterial blood gas levels are maintained through respiratory chemoreflexes, mediated by central (CCR) in the CNS and peripheral (PCR) chemoreceptors located in the carotid bodies. The interaction between central and peripheral chemoreceptors is controversial, and few studies have investigated this interaction in awake healthy humans, in part due to methodological challenges. We investigated the interaction between the CCRs and PCRs in healthy humans using a transient hypoxia test (three consecutive breaths of 100% N2 ; TT-HVR), which targets the stimulus and temporal domain specificity of the PCRs. TT-HVRs were superimposed upon three randomized background levels of steady-state inspired fraction of normoxic CO2 (FI CO2 ; 0, 0.02 and 0.04). Chemostimuli (calculated oxygen saturation; ScO2 ) and respiratory variable responses (respiratory rate, inspired tidal volume and ventilation; RR , VTI , V̇I ), were averaged from all three TT-HVR trials at each FI CO2 level. Responses were assessed as (a) a change from BL (delta; ∆) and (b) indexed against ∆ScO2 . Aside from a significantly lower ∆VTI response in 0.04 FI CO2 (P = 0.01), the hypoxic rate responses (∆RR or ∆RR /∆ScO2 ; P = 0.46, P = 0.81), hypoxic tidal volume response (∆VTI /∆ScO2 ; P = 0.08) and the hypoxic ventilatory responses (∆V̇I and (∆V̇I /∆ScO2 ; P = 0.09 and P = 0.31) were not significantly different across FI CO2 trials. Our data suggests simple addition between central and peripheral chemoreceptors in V̇I , which is mediated through simple addition in RR responses, but hypo-addition in VTI responses. Our study adds important new data in reconciling chemoreceptor interaction in awake healthy humans, and is consistent with previous reports of simple addition in intact rodents and humans. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kristin M Milloy
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | - Matthew G White
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | - Janelle O C Chicilo
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | | | - Jamie R Pfoh
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Canada
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15
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Olofsen E, Algera MH, Moss L, Dobbins RL, Groeneveld GJ, van Velzen M, Niesters M, Dahan A, Laffont CM. Modelling buprenorphine reduction of fentanyl-induced respiratory depression. JCI Insight 2022; 7:156973. [PMID: 35316224 PMCID: PMC9090248 DOI: 10.1172/jci.insight.156973] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 03/18/2022] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Potent synthetic opioids, such as fentanyl, are increasingly abused, resulting in unprecedented numbers of fatalities from respiratory depression. Treatment with the high-affinity mu-opioid receptor partial agonist buprenorphine may prevent fatalities by reducing binding of potent opioids to the opioid receptor, limiting respiratory depression. METHODS To characterize buprenorphine-fentanyl interaction at the level of the mu-opioid receptor in 2 populations (opioid-naive individuals and individuals who chronically use high-dose opioids), the effects of escalating i.v. fentanyl doses with range 0.075–0.35 mg/70 kg (opioid naive) and 0.25–0.70 mg/70 kg (chronic opioid use) on iso-hypercapnic ventilation at 2–3 background doses of buprenorphine (target plasma concentrations range: 0.2–5 ng/mL) were quantified using receptor association/dissociation models combined with biophase distribution models. RESULTS Buprenorphine produced mild respiratory depression, while high doses of fentanyl caused pronounced respiratory depression and apnea in both populations. When combined with fentanyl, buprenorphine produced a receptor binding–dependent reduction of fentanyl-induced respiratory depression in both populations. In individuals with chronic opioid use, at buprenorphine plasma concentrations of 2 ng/mL or higher, a protective effect against high-dose fentanyl was observed. CONCLUSION Overall, the results indicate that when buprenorphine mu-opioid receptor occupancy is sufficiently high, fentanyl is unable to activate the mu-opioid receptor and consequently will not cause further respiratory depression in addition to the mild respiratory effects of buprenorphine. TRIAL REGISTRATION Trialregister.nl, no. NL7028 (https://www.trialregister.nl/trial/7028) FUNDING Indivior Inc., North Chesterfield, Virginia, USA.
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Affiliation(s)
- Erik Olofsen
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Marijke Hyke Algera
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Laurence Moss
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Robert L Dobbins
- Drug Discovery and Translational Medicine, Indivior Inc., North Chesterfield, United States of America
| | - Geert J Groeneveld
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Monique van Velzen
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Marieke Niesters
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Albert Dahan
- Department of Anesthesiology, Leiden University Medical Center, Leiden, Netherlands
| | - Celine M Laffont
- Quantitative Clinical Pharmacology, Modeling and Simulation, Indivior Inc., North Chesterfield, United States of America
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16
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Dempsey JA, Neder JA, Phillips DB, O'Donnell DE. The physiology and pathophysiology of exercise hyperpnea. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:201-232. [PMID: 35965027 DOI: 10.1016/b978-0-323-91534-2.00001-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In health, the near-eucapnic, highly efficient hyperpnea during mild-to-moderate intensity exercise is driven by three obligatory contributions, namely, feedforward central command from supra-medullary locomotor centers, feedback from limb muscle afferents, and respiratory CO2 exchange (V̇CO2). Inhibiting each of these stimuli during exercise elicits a reduction in hyperpnea even in the continuing presence of the other major stimuli. However, the relative contribution of each stimulus to the hyperpnea remains unknown as does the means by which V̇CO2 is sensed. Mediation of the hyperventilatory response to exercise in health is attributed to the multiple feedback and feedforward stimuli resulting from muscle fatigue. In patients with COPD, diaphragm EMG amplitude and its relation to ventilatory output are used to decipher mechanisms underlying the patients' abnormal ventilatory responses, dynamic lung hyperinflation and dyspnea during exercise. Key contributions to these exercise-limiting responses across the spectrum of COPD severity include high dead space ventilation, an excessive neural drive to breathe and highly fatigable limb muscles, together with mechanical constraints on ventilation. Major controversies concerning control of exercise hyperpnea are discussed along with the need for innovative research to uncover the link of metabolism to breathing in health and disease.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, United States.
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
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17
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Vehmeijer WB, Jonkman K, Hardarson SH, Aarts L, Stefansson E, Dahan A, Schalij‐Delfos NE. Retinal oximetry with a prototype handheld oximeter during hyperoxia. Acta Ophthalmol 2021; 99:e1390-e1395. [PMID: 33650317 PMCID: PMC9543559 DOI: 10.1111/aos.14817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 01/29/2021] [Accepted: 02/04/2021] [Indexed: 11/30/2022]
Abstract
PURPOSE Retinal oximetry measures oxygen saturation in retinal vessels. With the introduction of a mobile handheld prototype oximeter, this technique will become available for a broader patient population including bedridden patients and newborn babies. The objective is to determine the sensitivity of this handheld oximeter in room air and during isocapnic hyperoxia. A comparison is made between the handheld oximeter and the Oxymap T1. METHODS Thirteen young healthy subjects with a mean age of 25 ± 2 years were recruited at the Leiden University Medical Center. Retinal oximetry images were acquired during normoxia and during isocapnic hyperoxia for both the prototype oximeter and the OxymapT1. Isocapnic hyperoxia was induced with the dynamic end-tidal forcing technique. For both oximeters, the oxygen saturation and vessel width were measured with Oxymap Analyzer software. The hyperoxic state was verified with blood gas analysis. RESULTS The mean oxygen saturation measured with the handheld oximeter in arterioles was 91.3% ± 3.9% during normoxia and 94.6% ± 3.9% during hyperoxia (p = 0.001). Oxygen saturation in venules was 56.3% ± 9.8% during normoxia and 82.2 ± 7.4% during hyperoxia (p < 0.001). For the Oxymap T1, the mean oxygen saturation for arterioles was 94.0% ± 2.6% during normoxia and 95.4%±3.2% during hyperoxia (p = 0.004). For the venules, the oxygen saturation was during normoxia 58.9%±3.2% and 84.3 ± 4.0% during hyperoxia (p < 0.001). CONCLUSION The handheld retinal oximeter is sensitive to the changes in inhaled oxygen concentration. A small increase in oxygen saturation was measured in the arterioles and a larger increase in the venules. The handheld oximeter gives similar values as the 'gold standard' Oxymap T1 oximeter.
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Affiliation(s)
- Wouter B. Vehmeijer
- Department of Ophthalmology Leiden University Medical Center Leiden The Netherlands
| | - Kelly Jonkman
- Department of Anesthesiology Leiden University Medical Center Leiden The Netherlands
| | | | - Leon Aarts
- Department of Anesthesiology Leiden University Medical Center Leiden The Netherlands
| | - Einar Stefansson
- Department of Physiology University of Iceland Reykjavik Iceland
- Department of Ophthalmology University of Iceland Landspítali, Reykjavik Iceland
| | - Albert Dahan
- Department of Anesthesiology Leiden University Medical Center Leiden The Netherlands
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18
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Ventilatory responses during and following hypercapnic gas challenge are impaired in male but not female endothelial NOS knock-out mice. Sci Rep 2021; 11:20557. [PMID: 34663876 PMCID: PMC8523677 DOI: 10.1038/s41598-021-99922-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 09/24/2021] [Indexed: 11/28/2022] Open
Abstract
The roles of endothelial nitric oxide synthase (eNOS) in the ventilatory responses during and after a hypercapnic gas challenge (HCC, 5% CO2, 21% O2, 74% N2) were assessed in freely-moving female and male wild-type (WT) C57BL6 mice and eNOS knock-out (eNOS-/-) mice of C57BL6 background using whole body plethysmography. HCC elicited an array of ventilatory responses that were similar in male and female WT mice, such as increases in breathing frequency (with falls in inspiratory and expiratory times), and increases in tidal volume, minute ventilation, peak inspiratory and expiratory flows, and inspiratory and expiratory drives. eNOS-/- male mice had smaller increases in minute ventilation, peak inspiratory flow and inspiratory drive, and smaller decreases in inspiratory time than WT males. Ventilatory responses in female eNOS-/- mice were similar to those in female WT mice. The ventilatory excitatory phase upon return to room-air was similar in both male and female WT mice. However, the post-HCC increases in frequency of breathing (with decreases in inspiratory times), and increases in tidal volume, minute ventilation, inspiratory drive (i.e., tidal volume/inspiratory time) and expiratory drive (i.e., tidal volume/expiratory time), and peak inspiratory and expiratory flows in male eNOS-/- mice were smaller than in male WT mice. In contrast, the post-HCC responses in female eNOS-/- mice were equal to those of the female WT mice. These findings provide the first evidence that the loss of eNOS affects the ventilatory responses during and after HCC in male C57BL6 mice, whereas female C57BL6 mice can compensate for the loss of eNOS, at least in respect to triggering ventilatory responses to HCC.
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19
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Getsy PM, Sundararajan S, May WJ, von Schill GC, McLaughlin DK, Palmer LA, Lewis SJ. Short-term facilitation of breathing upon cessation of hypoxic challenge is impaired in male but not female endothelial NOS knock-out mice. Sci Rep 2021; 11:18346. [PMID: 34526532 PMCID: PMC8443732 DOI: 10.1038/s41598-021-97322-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 08/09/2021] [Indexed: 02/08/2023] Open
Abstract
Decreases in arterial blood oxygen stimulate increases in minute ventilation via activation of peripheral and central respiratory structures. This study evaluates the role of endothelial nitric oxide synthase (eNOS) in the expression of the ventilatory responses during and following a hypoxic gas challenge (HXC, 10% O2, 90% N2) in freely moving male and female wild-type (WT) C57BL6 and eNOS knock-out (eNOS-/-) mice. Exposure to HXC caused an array of responses (of similar magnitude and duration) in both male and female WT mice such as, rapid increases in frequency of breathing, tidal volume, minute ventilation and peak inspiratory and expiratory flows, that were subject to pronounced roll-off. The responses to HXC in male eNOS-/- mice were similar to male WT mice. In contrast, several of the ventilatory responses in female eNOS-/- mice (e.g., frequency of breathing, and expiratory drive) were greater compared to female WT mice. Upon return to room-air, male and female WT mice showed similar excitatory ventilatory responses (i.e., short-term potentiation phase). These responses were markedly reduced in male eNOS-/- mice, whereas female eNOS-/- mice displayed robust post-HXC responses that were similar to those in female WT mice. Our data demonstrates that eNOS plays important roles in (1) ventilatory responses to HXC in female compared to male C57BL6 mice; and (2) expression of post-HXC responses in male, but not female C57BL6 mice. These data support existing evidence that sex, and the functional roles of specific proteins (e.g., eNOS) have profound influences on ventilatory processes, including the responses to HXC.
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Affiliation(s)
- Paulina M. Getsy
- grid.67105.350000 0001 2164 3847Department of Pediatrics, Biomedical Research Building BRB 319, Case Western Reserve University, 10900 Euclid Avenue Mail Stop 1714, Cleveland, OH 44106-1714 USA ,grid.67105.350000 0001 2164 3847Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH USA
| | - Sripriya Sundararajan
- grid.27755.320000 0000 9136 933XPediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA USA ,grid.411024.20000 0001 2175 4264Present Address: Division of Neonatology, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Walter J. May
- grid.27755.320000 0000 9136 933XPediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA USA
| | - Graham C. von Schill
- grid.27755.320000 0000 9136 933XPediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA USA
| | - Dylan K. McLaughlin
- grid.27755.320000 0000 9136 933XPediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA USA
| | - Lisa A. Palmer
- grid.27755.320000 0000 9136 933XPediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA USA
| | - Stephen J. Lewis
- grid.67105.350000 0001 2164 3847Department of Pediatrics, Biomedical Research Building BRB 319, Case Western Reserve University, 10900 Euclid Avenue Mail Stop 1714, Cleveland, OH 44106-1714 USA ,grid.67105.350000 0001 2164 3847Department of Pharmacology, Case Western Reserve University, Cleveland, OH USA ,grid.67105.350000 0001 2164 3847Functional Electrical Stimulation Center, Case Western Reserve University, Cleveland, OH USA
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20
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Getsy PM, Sundararajan S, Lewis SJ. Carotid sinus nerve transection abolishes the facilitation of breathing that occurs upon cessation of a hypercapnic gas challenge in male mice. J Appl Physiol (1985) 2021; 131:821-835. [PMID: 34236243 DOI: 10.1152/japplphysiol.01031.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Arterial pCO2 elevations increase minute ventilation via activation of chemosensors within the carotid body (CB) and brainstem. Although the roles of CB chemoafferents in the hypercapnic (HC) ventilatory response have been investigated, there are no studies reporting the role of these chemoafferents in the ventilatory responses to a HC challenge or the responses that occur upon return to room air, in freely moving mice. This study found that an HC challenge (5% CO2, 21% O2, 74% N2 for 15 min) elicited an array of responses, including increases in frequency of breathing (accompanied by decreases in inspiratory and expiratory times), and increases in tidal volume, minute ventilation, peak inspiratory and expiratory flows, and inspiratory and expiratory drives in sham-operated (SHAM) adult male C57BL6 mice, and that return to room air elicited a brief excitatory phase followed by gradual recovery of all parameters toward baseline values over a 15-min period. The array of ventilatory responses to the HC challenge in mice with bilateral carotid sinus nerve transection (CSNX) performed 7 days previously occurred more slowly but reached similar maxima as SHAM mice. A major finding was responses upon return to room air were dramatically lower in CSNX mice than SHAM mice, and the parameters returned to baseline values within 1-2 min in CSNX mice, whereas it took much longer in SHAM mice. These findings are the first evidence that CB chemoafferents play a key role in initiating the ventilatory responses to HC challenge in C57BL6 mice and are essential for the expression of post-HC ventilatory responses.NEW & NOTEWORTHY This study presents the first evidence that carotid body chemoafferents play a key role in initiating the ventilatory responses, such as increases in frequency of breathing, tidal volume, and minute ventilation that occur in response to a hypercapnic gas challenge in freely moving C57BL6 mice. Our study also demonstrates for the first time that these chemoafferents are essential for the expression of the ventilatory responses that occur upon return to room air in these mice.
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Affiliation(s)
- Paulina M Getsy
- Department of Pediatrics, Case Western University, Cleveland, Ohio
| | - Sripriya Sundararajan
- Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Stephen J Lewis
- Department of Pediatrics, Case Western University, Cleveland, Ohio.,Department of Pharmacology, Case Western University, Cleveland, Ohio
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21
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Lactate sensing mechanisms in arterial chemoreceptor cells. Nat Commun 2021; 12:4166. [PMID: 34230483 PMCID: PMC8260783 DOI: 10.1038/s41467-021-24444-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 06/08/2021] [Indexed: 12/17/2022] Open
Abstract
Classically considered a by-product of anaerobic metabolism, lactate is now viewed as a fundamental fuel for oxidative phosphorylation in mitochondria, and preferred over glucose by many tissues. Lactate is also a signaling molecule of increasing medical relevance. Lactate levels in the blood can increase in both normal and pathophysiological conditions (e.g., hypoxia, physical exercise, or sepsis), however the manner by which these changes are sensed and induce adaptive responses is unknown. Here we show that the carotid body (CB) is essential for lactate homeostasis and that CB glomus cells, the main oxygen sensing arterial chemoreceptors, are also lactate sensors. Lactate is transported into glomus cells, leading to a rapid increase in the cytosolic NADH/NAD+ ratio. This in turn activates membrane cation channels, leading to cell depolarization, action potential firing, and Ca2+ influx. Lactate also decreases intracellular pH and increases mitochondrial reactive oxygen species production, which further activates glomus cells. Lactate and hypoxia, although sensed by separate mechanisms, share the same final signaling pathway and jointly activate glomus cells to potentiate compensatory cardiorespiratory reflexes. Lactate levels in blood change during hypoxia or exercise, however whether this variable is sensed to evoke adaptive responses is unknown. Here the authors show that oxygen-sensing carotid body cells stimulated by hypoxia are also activated by lactate to potentiate a compensatory ventilatory response.
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22
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Abstract
Sleep is essential for healthy being and healthy functioning of human body as a whole, as well as each organ and system. Sleep disorders, such as sleep-disordered breathing, insomnia, sleep fragmentation, and sleep deprivation are associated with the deterioration in human body functioning and increased cardiovascular risks. However, owing to the complex regulation and heterogeneous state sleep per se can be associated with cardiovascular dysfunction in susceptible subjects. The understanding of sleep as a multidimensional concept is important for better prevention and treatment of cardiovascular diseases.
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Affiliation(s)
- Lyudmila Korostovtseva
- Sleep Laboratory, Research Department for Hypertension, Department for Cardiology, Almazov National Medical Research Centre, 2 Akkuratov Street, St Petersburg 197341, Russia.
| | - Mikhail Bochkarev
- Sleep Laboratory, Research Department for Hypertension, Almazov National Medical Research Centre, 2 Akkuratov Street, St Petersburg 197341, Russia
| | - Yurii Sviryaev
- Research Department for Hypertension, Almazov National Medical Research Centre, 2 Akkuratov Street, St Petersburg 197341, Russia
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23
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Niewinski P, Tubek S, Paton JFR, Banasiak W, Ponikowski P. Oxygenation pattern and compensatory responses to hypoxia and hypercapnia following bilateral carotid body resection in humans. J Physiol 2021; 599:2323-2340. [DOI: 10.1113/jp281319] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/12/2021] [Indexed: 11/08/2022] Open
Affiliation(s)
- Piotr Niewinski
- Department of Heart Diseases Wroclaw Medical University Wroclaw Poland
| | - Stanislaw Tubek
- Department of Heart Diseases Wroclaw Medical University Wroclaw Poland
| | - Julian F. R. Paton
- Department of Physiology Faculty of Medical & Health Sciences University of Auckland Park Road Grafton Auckland New Zealand
| | | | - Piotr Ponikowski
- Department of Heart Diseases Wroclaw Medical University Wroclaw Poland
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24
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Algera MH, Olofsen E, Moss L, Dobbins RL, Niesters M, van Velzen M, Groeneveld GJ, Heuberger J, Laffont CM, Dahan A. Tolerance to Opioid-Induced Respiratory Depression in Chronic High-Dose Opioid Users: A Model-Based Comparison With Opioid-Naïve Individuals. Clin Pharmacol Ther 2021; 109:637-645. [PMID: 32865832 PMCID: PMC7983936 DOI: 10.1002/cpt.2027] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 08/11/2020] [Indexed: 12/24/2022]
Abstract
Chronic opioid consumption is associated with addiction, physical dependence, and tolerance. Tolerance results in dose escalation to maintain the desired opioid effect. Intake of high-dose or potent opioids may cause life-threatening respiratory depression, an effect that may be reduced by tolerance. We performed a pharmacokinetic-pharmacodynamic analysis of the respiratory effects of fentanyl in chronic opioid users and opioid-naïve subjects to quantify tolerance to respiratory depression. Fourteen opioid-naïve individuals and eight chronic opioid users received escalating doses of intravenous fentanyl (opioid-naïve subjects: 75-350 µg/70 kg; chronic users: 250-700 µg/70 kg). Isohypercapnic ventilation was measured and the fentanyl plasma concentration-ventilation data were analyzed using nonlinear mixed-effects modeling. Apneic events occurred in opioid-naïve subjects after a cumulative fentanyl dose (per 70 kg) of 225 (n = 3) and 475 µg (n = 6), and in 7 chronic opioid users after a cumulative dose of 600 (n = 2), 1,100 (n = 2), and 1,800 µg (n = 3). The time course of fentanyl's respiratory depressant effect was characterized using a biophase equilibration model in combination with an inhibitory maximum effect (Emax ) model. Differences in tolerance between populations were successfully modeled. The effect-site concentration causing 50% ventilatory depression, was 0.42 ± 0.07 ng/mL in opioid-naïve subjects and 1.82 ± 0.39 ng/mL in chronic opioid users, indicative of a 4.3-fold sensitivity difference. Despite higher tolerance to fentanyl-induced respiratory depression, apnea still occurred in the opioid-tolerant population indicative of the potential danger of high-dose opioids in causing life-threatening respiratory depression in all individuals, opioid-naïve and opioid-tolerant.
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Affiliation(s)
- Marijke Hyke Algera
- Department of AnesthesiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Erik Olofsen
- Department of AnesthesiologyLeiden University Medical CenterLeidenThe Netherlands
| | | | | | - Marieke Niesters
- Department of AnesthesiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Monique van Velzen
- Department of AnesthesiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Geert Jan Groeneveld
- Department of AnesthesiologyLeiden University Medical CenterLeidenThe Netherlands
- Centre for Human Drug ResearchLeidenThe Netherlands
| | | | | | - Albert Dahan
- Department of AnesthesiologyLeiden University Medical CenterLeidenThe Netherlands
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25
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Simonson TS, Baker TL, Banzett RB, Bishop T, Dempsey JA, Feldman JL, Guyenet PG, Hodson EJ, Mitchell GS, Moya EA, Nokes BT, Orr JE, Owens RL, Poulin M, Rawling JM, Schmickl CN, Watters JJ, Younes M, Malhotra A. Silent hypoxaemia in COVID-19 patients. J Physiol 2021; 599:1057-1065. [PMID: 33347610 PMCID: PMC7902403 DOI: 10.1113/jp280769] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 12/07/2020] [Indexed: 12/14/2022] Open
Abstract
The clinical presentation of COVID-19 due to infection with SARS-CoV-2 is highly variable with the majority of patients having mild symptoms while others develop severe respiratory failure. The reason for this variability is unclear but is in critical need of investigation. Some COVID-19 patients have been labelled with 'happy hypoxia', in which patient complaints of dyspnoea and observable signs of respiratory distress are reported to be absent. Based on ongoing debate, we highlight key respiratory and neurological components that could underlie variation in the presentation of silent hypoxaemia and define priorities for subsequent investigation.
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Affiliation(s)
- Tatum S Simonson
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Tracy L Baker
- Department of Comparative Biosciences, University of Wisconsin -, Madison, WI, USA
| | - Robert B Banzett
- Division of Pulmonary, Critical Care, & Sleep Medicine Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Tammie Bishop
- Target Discovery Institute, University of Oxford, Oxford, UK
| | - Jerome A Dempsey
- Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin -, Madison, WI, USA
| | - Jack L Feldman
- Department of Neurobiology, University of California, Los Angeles, CA, USA
| | - Patrice G Guyenet
- Department of Pharmacology, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Emma J Hodson
- The Francis Crick Institute, London, UK
- The Department of Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, UK
| | - Gordon S Mitchell
- Department of Physical Therapy, Center for Respiratory Research and Rehabilitation, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA
| | - Esteban A Moya
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Brandon T Nokes
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Jeremy E Orr
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Robert L Owens
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Marc Poulin
- Departments of Physiology & Pharmacology and Clinical Neurosciences, Cumming School of Medicine and Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Jean M Rawling
- Departments of Family Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Christopher N Schmickl
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Jyoti J Watters
- Department of Comparative Biosciences, University of Wisconsin -, Madison, WI, USA
| | - Magdy Younes
- Sleep Disorders Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
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26
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Simonson TS, Baker TL, Banzett RB, Bishop T, Dempsey JA, Feldman JL, Guyenet PG, Hodson EJ, Mitchell GS, Moya EA, Nokes BT, Orr JE, Owens RL, Poulin M, Rawling JM, Schmickl CN, Watters JJ, Younes M, Malhotra A. Silent hypoxaemia in COVID-19 patients. J Physiol 2021. [PMID: 33347610 DOI: 10.1113/tjp.v599.410.1113/jp280769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
The clinical presentation of COVID-19 due to infection with SARS-CoV-2 is highly variable with the majority of patients having mild symptoms while others develop severe respiratory failure. The reason for this variability is unclear but is in critical need of investigation. Some COVID-19 patients have been labelled with 'happy hypoxia', in which patient complaints of dyspnoea and observable signs of respiratory distress are reported to be absent. Based on ongoing debate, we highlight key respiratory and neurological components that could underlie variation in the presentation of silent hypoxaemia and define priorities for subsequent investigation.
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Affiliation(s)
- Tatum S Simonson
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Tracy L Baker
- Department of Comparative Biosciences, University of Wisconsin -, Madison, WI, USA
| | - Robert B Banzett
- Division of Pulmonary, Critical Care, & Sleep Medicine Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Tammie Bishop
- Target Discovery Institute, University of Oxford, Oxford, UK
| | - Jerome A Dempsey
- Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin -, Madison, WI, USA
| | - Jack L Feldman
- Department of Neurobiology, University of California, Los Angeles, CA, USA
| | - Patrice G Guyenet
- Department of Pharmacology, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Emma J Hodson
- The Francis Crick Institute, London, UK
- The Department of Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, UK
| | - Gordon S Mitchell
- Department of Physical Therapy, Center for Respiratory Research and Rehabilitation, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA
| | - Esteban A Moya
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Brandon T Nokes
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Jeremy E Orr
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Robert L Owens
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Marc Poulin
- Departments of Physiology & Pharmacology and Clinical Neurosciences, Cumming School of Medicine and Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Jean M Rawling
- Departments of Family Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Christopher N Schmickl
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Jyoti J Watters
- Department of Comparative Biosciences, University of Wisconsin -, Madison, WI, USA
| | - Magdy Younes
- Sleep Disorders Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
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27
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Falcão LF, da Silva Pontes L, Afonso da Silva BG, Vieira da Silva Franco KM, Costa LA, Barbosa Rocha RS, Simões Quaresma JA. The complexity of respiratory disease associated with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection: From immunopathogenesis to respiratory therapy. Rev Med Virol 2020. [DOI: 10.1002/rmv.2167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Luiz Fábio Falcão
- Center for Biological and Health Sciences State University of Pará Belém Pará Brazil
| | | | | | | | - Luiz Adriano Costa
- Center for Biological and Health Sciences State University of Pará Belém Pará Brazil
| | | | - Juarez Antônio Simões Quaresma
- Center for Biological and Health Sciences State University of Pará Belém Pará Brazil
- Evandro Chagas Institute Ministry of Health Ananindeua Pará Brazil
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28
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Rastogi R, Badr MS, Ahmed A, Chowdhuri S. Amelioration of sleep-disordered breathing with supplemental oxygen in older adults. J Appl Physiol (1985) 2020; 129:1441-1450. [PMID: 32969781 DOI: 10.1152/japplphysiol.00253.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elderly adults demonstrate increased propensity for breathing instability during sleep compared with younger adults, and this may contribute to increased prevalence of sleep-disordered breathing (SDB) in this population. Hence, in older adults with SDB, we examined whether addition of supplemental oxygen (O2) will stabilize breathing during sleep and alleviate SDB. We hypothesized that exposure to supplemental O2 during non-rapid eye movement (NREM) sleep will stabilize breathing and will alleviate SDB by reducing ventilatory chemoresponsiveness and by widening the carbon dioxide (CO2) reserve. We studied 10 older adults with mild-to-moderate SDB who were randomized to undergo noninvasive bilevel mechanical ventilation with exposure to room air or supplemental O2 (Oxy) to determine the CO2 reserve, apneic threshold (AT), and controller and plant gains. Supplemental O2 was introduced during sleep to achieve a steady-state O2 saturation ≥95% and fraction of inspired O2 at 40%-50%. The CO2 reserve increased significantly during Oxy versus room air (-4.2 ± 0.5 mmHg vs. -3.2 ± 0.5 mmHg, P = 0.03). Compared with room air, Oxy was associated with a significant decline in the controller gain (1.9 ± 0.4 L/min/mmHg vs. 2.5 ± 0.5 L/min/mmHg, P = 0.04), with reductions in the apnea-hypopnea index (11.8 ± 2.0/h vs. 24.4 ± 5.6/h, P = 0.006) and central apnea-hypopnea index (1.7 ± 0.6/h vs. 6.9 ± 3.9/h, P = 0.03). The AT and plant gain were unchanged. Thus, a reduced slope of CO2 response resulted in an increased CO2 reserve. In conclusion, supplemental O2 reduced SDB in older adults during NREM sleep via reduction in chemoresponsiveness and central respiratory events.NEW & NOTEWORTHY This study demonstrates for the first time in elderly adults without heart disease that intervention with supplemental oxygen in the clinical range will ameliorate central apneas and hypopneas by decreasing the propensity to central apnea through decreased chemoreflex sensitivity, even in the absence of a reduction in the plant gain. Thus, the study provides physiological evidence for use of supplemental oxygen as therapy for mild-to-moderate SDB in this vulnerable population.
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Affiliation(s)
- Ruchi Rastogi
- Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan.,Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - M S Badr
- Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan.,Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - A Ahmed
- Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - S Chowdhuri
- Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan.,Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
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29
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Prasad B, Morgan BJ, Gupta A, Pegelow DF, Teodorescu M, Dopp JM, Dempsey JA. The need for specificity in quantifying neurocirculatory vs. respiratory effects of eucapnic hypoxia and transient hyperoxia. J Physiol 2020; 598:4803-4819. [PMID: 32770545 DOI: 10.1113/jp280515] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 08/04/2020] [Indexed: 12/24/2022] Open
Abstract
KEY POINTS The carotid chemoreceptor mediates the ventilatory and muscle sympathetic nerve activity (MSNA) responses to hypoxia and contributes to tonic sympathetic and respiratory drives. It is often presumed that both excitatory and inhibitory tests of chemoreflex function show congruence in the end-organ responses. Ventilatory and neurocirculatory (MSNA, blood pressure and heart rate) responses to chemoreflex inhibition elicited by transient hyperoxia and to chemoreflex excitation produced by steady-state eucapnic hypoxia were measured in a cohort of 82 middle-aged individuals. Ventilatory and MSNA responsiveness to hyperoxia and hypoxia were not significantly correlated within individuals. It was concluded that ventilatory responses to hypoxia and hyperoxia do not predict MSNA responses and it is recommended that tests using the specific outcome of interest, i.e. MSNA or ventilation, are required. Transient hyperoxia is recommended as a sensitive and reliable means of quantifying tonic chemoreceptor-driven levels of sympathetic nervous system activity and respiratory drive. ABSTRACT Hypersensitivity of the carotid chemoreceptor leading to sympathetic nervous system activation and ventilatory instability has been implicated in the pathogenesis and consequences of several common clinical conditions. A variety of treatment approaches aimed at lessening chemoreceptor-driven sympathetic overactivity are now under investigation; thus, the ability to quantify this outcome variable with specificity and precision is crucial. Accordingly, we measured ventilatory and neurocirculatory responses to chemoreflex inhibition elicited by transient hyperoxia and chemoreflex excitation produced by exposure to graded, steady-state eucapnic hypoxia in middle-aged men and women (n = 82) with continuous positive airway pressure-treated obstructive sleep apnoea. Progressive, eucapnic hypoxia produced robust and highly variable increases in ventilation (+83 ± 59%) and muscle sympathetic nerve activity (MSNA) burst frequency (+55 ± 31%), whereas transient hyperoxia caused marked reductions in these variables (-35 ± 14% and -42 ± 16%, respectively). Coefficients of variation for ventilatory and MSNA burst frequency responses, indicating test-retest reproducibility, were respectively 9% and 24% for hyperoxia and 35% and 28% for hypoxia. Based on statistical measures of rank correlation or even comparisons across quartiles of corresponding ventilatory and MSNA responses, we found that the magnitudes of ventilatory inhibition with hyperoxia or excitation with eucapnic hypoxia were not correlated with corresponding MSNA responses within individuals. We conclude that, in conscious, behaving humans, ventilatory sensitivities to progressive, steady-state, eucapnic hypoxia and transient hyperoxia do not predict MSNA responsiveness. Our findings also support the use of transient hyperoxia as a reliable, sensitive, measure of the carotid chemoreceptor contribution to tonic sympathetic nervous system activity and respiratory drive.
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Affiliation(s)
- Bharati Prasad
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.,Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Ahana Gupta
- GPPA Medical Scholars Program, University of Illinois at Chicago, Chicago, IL, USA
| | - David F Pegelow
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Mihaela Teodorescu
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - John M Dopp
- Pharmacy Practice Division, School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA
| | - Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.,Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, WI, USA
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30
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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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31
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Wan HY, Weavil JC, Thurston TS, Georgescu VP, Hureau TJ, Bledsoe AD, Buys MJ, Jessop JE, Richardson RS, Amann M. The exercise pressor reflex and chemoreflex interaction: cardiovascular implications for the exercising human. J Physiol 2020; 598:2311-2321. [PMID: 32170732 DOI: 10.1113/jp279456] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/10/2020] [Indexed: 01/11/2023] Open
Abstract
KEY POINTS Although the exercise pressor reflex (EPR) and the chemoreflex (CR) are recognized for their sympathoexcitatory effect, the cardiovascular implication of their interaction remains elusive. We quantified the individual and interactive cardiovascular consequences of these reflexes during exercise and revealed various modes of interaction. The EPR and hypoxia-induced CR interaction is hyper-additive for blood pressure and heart rate (responses during co-activation of the two reflexes are greater than the summation of the responses evoked by each reflex) and hypo-additive for peripheral haemodynamics (responses during co-activation of the reflexes are smaller than the summated responses). The EPR and hypercapnia-induced CR interaction results in a simple addition of the individual responses to each reflex (i.e. additive interaction). Collectively, EPR:CR co-activation results in significant cardiovascular interactions with restriction in peripheral haemodynamics, resulting from the EPR:CR interaction in hypoxia, likely having the most crucial impact on the functional capacity of an exercising human. ABSTRACT We investigated the interactive effect of the exercise pressor reflex (EPR) and the chemoreflex (CR) on the cardiovascular response to exercise. Eleven healthy participants (5 females) completed a total of six bouts of single-leg knee-extension exercise (60% peak work rate, 4 min each) either with or without lumbar intrathecal fentanyl to attenuate group III/IV afferent feedback from lower limbs to modify the EPR, while breathing either ambient air, normocapnic hypoxia (Sa O2 ∼79%, Pa O2 ∼43 mmHg, Pa CO2 ∼33 mmHg, pH ∼7.39), or normoxic hypercapnia (Sa O2 ∼98%, Pa O2 ∼105 mmHg, Pa CO2 ∼50 mmHg, pH ∼7.26) to modify the CR. During co-activation of the EPR and the hypoxia-induced CR (O2 -CR), mean arterial pressure and heart rate were significantly greater, whereas leg blood flow and leg vascular conductance were significantly lower than the summation of the responses evoked by each reflex alone. During co-activation of the EPR and the hypercapnia-induced CR (CO2 -CR), the haemodynamic responses were not different from the summated responses to each reflex response alone (P ≥ 0.1). Therefore, while the interaction resulting from the EPR:O2 -CR co-activation is hyper-additive for blood pressure and heart rate, and hypo-additive for peripheral haemodynamics, the interaction resulting from the EPR:CO2 -CR co-activation is simply additive for all cardiovascular parameters. Thus, EPR:CR co-activation results in significant interactions between cardiovascular reflexes, with the impact differing when the CR activation is achieved by hypoxia or hypercapnia. Since the EPR:CR co-activation with hypoxia potentiates the pressor response and restricts blood flow to contracting muscles, this interaction entails the most functional impact on an exercising human.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Vincent P Georgescu
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Thomas J Hureau
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Michael J Buys
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
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Dempsey JA, Smith CA. Update on Chemoreception: Influence on Cardiorespiratory Regulation and Pathophysiology. Clin Chest Med 2020; 40:269-283. [PMID: 31078209 DOI: 10.1016/j.ccm.2019.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We examine recent findings that have revealed interdependence of function within the chemoreceptor pathway regulating breathing and sympathetic vasomotor activity and the hypersensitization of these reflexes in chronic disease states. Recommendations are made as to how these states of hyperreflexia in chemoreceptors and muscle afferents might be modified in treating sleep apnea, drug-resistant hypertension, chronic heart failure-induced sympathoexcitation, and the exertional dyspnea of chronic obstructive pulmonary disease.
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Affiliation(s)
- Jerome A Dempsey
- Department Population Health Sciences, University of Wisconsin-Madison, 707 WARF Building, 610 N. Walnut Street, WI 53726, USA.
| | - Curtis A Smith
- Department Population Health Sciences, University of Wisconsin-Madison, 707 WARF Building, 610 N. Walnut Street, WI 53726, USA
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Abstract
Abstract
Editor’s Perspective
What We Already Know about This Topic
What This Article Tells Us That Is New
Background
There is an ongoing need for potent opioids with less adverse effects than commonly used opioids. R-dihydroetorphine is a full opioid receptor agonist with relatively high affinity at the μ-, δ- and κ-opioid receptors and low affinity at the nociception/orphanin FQ receptor. The authors quantified its antinociceptive and respiratory effects in healthy volunteers. The authors hypothesized that given its receptor profile, R-dihydroetorphine will exhibit an apparent plateau in respiratory depression, but not in antinociception.
Methods
The authors performed a population pharmacokinetic–pharmacodynamic study (Eudract registration No. 2009-010880-17). Four intravenous R-dihydroetorphine doses were studied: 12.5, 75, 125, and 150 ng/kg (infused more than 10 min) in 4 of 4, 6 of 6, 6 of 6, and 4 of 4 male subjects in pain and respiratory studies, respectively. The authors measured isohypercapnic ventilation, pain threshold, and tolerance responses to electrical noxious stimulation and arterial blood samples for pharmacokinetic analysis.
Results
R-dihydroetorphine displayed a dose-dependent increase in peak plasma concentrations at the end of the infusion. Concentration-effect relationships differed significantly between endpoints. R-dihydroetorphine produced respiratory depression best described by a sigmoid EMAX-model. A 50% reduction in ventilation in between baseline and minimum ventilation was observed at an R-dihydroetorphine concentration of 17 ± 4 pg/ml (median ± standard error of the estimate). The maximum reduction in ventilation observed was at 33% of baseline. In contrast, over the dose range studied, R-dihydroetorphine produced dose-dependent analgesia best described by a linear model. A 50% increase in stimulus intensity was observed at 34 ± 11 pg/ml.
Conclusions
Over the dose range studied, R-dihydroetorphine exhibited a plateau in respiratory depression, but not in analgesia. Whether these experimental advantages extrapolate to the clinical setting and whether analgesia has no plateau at higher concentrations than investigated requires further studies.
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Cracchiolo M, Sacramento JF, Mazzoni A, Panarese A, Carpaneto J, Conde SV, Micera S. Decoding Neural Metabolic Markers From the Carotid Sinus Nerve in a Type 2 Diabetes Model. IEEE Trans Neural Syst Rehabil Eng 2019; 27:2034-2043. [DOI: 10.1109/tnsre.2019.2942398] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
Abstract
Editor’s Perspective
What We Already Know about This Topic
What This Article Tells Us That Is New
Background
The ventilatory response to hypoxia is a life-saving chemoreflex originating at the carotid bodies that is impaired by nondepolarizing neuromuscular blocking agents. This study evaluated the effect of three strategies for reversal of a partial neuromuscular block on ventilatory control in 34 healthy male volunteers on the chemoreflex. The hypothesis was that the hypoxic ventilatory response is fully restored following the return to a train-of-four ratio of 1.
Methods
In this single-center, experimental, randomized, controlled trial, ventilatory responses to 5-min hypoxia (oxygen saturation, 80 ± 2%) and ventilation at hyperoxic isohypercapnia (end-tidal carbon dioxide concentration, 55 mmHg) were obtained at baseline, during rocuronium-induced partial neuromuscular block (train-of-four ratio of 0.7 measured at the adductor pollicis muscle by electromyography), and following reversal until the train-of-four ratio reached unity with placebo (n = 12), 1 mg neostigmine/0.5 mg atropine (n = 11), or 2 mg/kg sugammadex (n = 11).
Results
This study confirmed that low-dose rocuronium reduced the ventilatory response to hypoxia from 0.55 ± 0.22 (baseline) to 0.31 ± 0.21 l · min−1 · %−1 (train-of-four ratio, 0.7; P < 0.001). Following full reversal as measured at the thumb, there was persistent residual blunting of the hypoxic ventilatory response (0.45 ± 0.16 l · min−1 · %−1; train-of-four ratio, 1.0; P < 0.001). Treatment effect was not significant (analysis of covariance, P = 0.299) with chemoreflex impairment in 5 (45%) subjects following sugammadex reversal, in 7 subjects (64%) following neostigmine reversal, and in 10 subjects (83%) after spontaneous reversal to a train-of-four ratio of 1.
Conclusions
Despite full reversal of partial neuromuscular block at the thumb, impairment of the peripheral chemoreflex may persist at train-of-four ratios greater than 0.9 following reversal with neostigmine and sugammadex or spontaneous recovery of the neuromuscular block.
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Abstract
The ventilatory control system is highly vulnerable to exogenous administered opioid analgesics. Particularly respiratory depression is a potentially lethal complication that may occur when opioids are overdosed or consumed in combination with other depressants such as sleep medication or alcohol. Fatalities occur in acute and chronic pain patients on opioid therapy and individuals that abuse prescription or illicit opioids for their hedonistic pleasure. One important strategy to mitigate opioid-induced respiratory depression is cotreatment with nonopioid respiratory stimulants. Effective stimulants prevent respiratory depression without affecting the analgesic opioid response. Several pharmaceutical classes of nonopioid respiratory stimulants are currently under investigation. The majority acts at sites within the brainstem respiratory network including drugs that act at α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (ampakines), 5-hydroxytryptamine receptor agonists, phospodiesterase-4 inhibitors, D1-dopamine receptor agonists, the endogenous peptide glycyl-glutamine, and thyrotropin-releasing hormone. Others act peripherally at potassium channels expressed on oxygen-sensing cells of the carotid bodies, such as doxapram and GAL021 (Galleon Pharmaceuticals Corp., USA). In this review we critically appraise the efficacy of these agents. We conclude that none of the experimental drugs are adequate for therapeutic use in opioid-induced respiratory depression and all need further study of efficacy and toxicity. All discussed drugs, however, do highlight potential mechanisms of action and possible templates for further study and development.
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Jaworski J, Bates JHT. Sources of breathing pattern variability in the respiratory feedback control loop. J Theor Biol 2019; 469:148-162. [PMID: 30831172 DOI: 10.1016/j.jtbi.2019.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 02/25/2019] [Accepted: 03/01/2019] [Indexed: 11/28/2022]
Abstract
The variability of the breath-to-breath breathing pattern, and its alterations in disease, may hold information of physiologic and/or diagnostic value. We hypothesized that this variability arises from the way that noise is processed within the respiratory feedback control loop, and that pathologic alterations to specific components within the system give rise to characteristic alterations in breathing pattern variability. We explored this hypothesis using a computational model of the respiratory control system that integrates mechanical factors, gas exchange processes, and chemoreceptor signals to simulate breathing patterns subject to the influences of random variability in each of the system components. We found that the greatest changes in the coefficient of variation (CV) of both breathing amplitude and timing were caused by increases in lung resistance and impairments in gas exchange, both common features of pulmonary disease. This suggests that breathing pattern variability may reflect discernible deterministic processes involved in the control of breathing.
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Affiliation(s)
- Jacek Jaworski
- Department of Applied Signal Processing, Blekinge Institute of Technology, Karlskrona, Sweden
| | - Jason H T Bates
- Department of Medicine, Larner College of Medicine, University of Vermont, 149 Beaumont Avenue, Burlington, VT 05405, United States.
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Bobadilla-Rosado LO, Garcia-Alva R, Anaya-Ayala JE, Peralta-Vazquez C, Hernandez-Sotelo K, Luna L, Cuen-Ojeda C, Hinojosa CA. Surgical Management of Bilateral Carotid Body Tumors. Ann Vasc Surg 2019; 57:187-193. [PMID: 30684613 DOI: 10.1016/j.avsg.2018.10.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 09/27/2018] [Accepted: 10/04/2018] [Indexed: 12/29/2022]
Abstract
BACKGROUND Carotid body tumors (CBTs) are rare neoplasms located in the carotid bifurcation. The majority of these tumors are unilateral; bilateral CBTs represent approximately 5% of all affected patients, and the recommended treatment is to surgically remove them in staged-planned surgeries. We describe the experience, outcomes, and the surgical management of bilateral CBTs in our institution. METHODS A retrospective review of CBTs patients was completed; patient demographics, comorbidities, lesion location, anatomic characteristics, surgical techniques, complications, reinterventions, and other factors that may influence outcomes were evaluated. RESULTS A total of 109 patients with CBTs were treated surgically; of these, 8 had bilateral CBTs (7%); the mean age was 56 years, and 7 (87%) were females. Thirteen surgical resections were performed, and in 2 of the cases, the pathology report was malignant (15%). Five were classified as Shamblin I (31%), 5 as Shamblin II (31%), and remaining 6 as Shamblin III (38%). The mean time between the first and second procedure was of 10.7 months. Complications included one case of neck hematoma requiring evacuation and postoperative neurologic complications occurred in three patients (one patient with facial and two with vocal cord palsies). None of the studied individuals had a family history of CBT, and all of them lived in altitude areas higher than 2000 meters above mean sea level (mamsl). The mean tumor size was 3.55 cm and 2.75 cm for right and left CBTs, respectively. CONCLUSIONS A better understanding of the clinical characteristics of patients with bilateral CBTs may lead to a more standardized and optimal management with fewer complications and a better quality of life afterward.
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Affiliation(s)
- Luis O Bobadilla-Rosado
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico
| | - Ramon Garcia-Alva
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico
| | - Javier E Anaya-Ayala
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico
| | - Cynthia Peralta-Vazquez
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico
| | - Kemberly Hernandez-Sotelo
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico
| | - Lizeth Luna
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico
| | - Cesar Cuen-Ojeda
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico
| | - Carlos A Hinojosa
- Department of Surgery, Section of Vascular Surgery and Endovascular Therapy, Instituto Nacional de Ciencias Médicas y Nutricion Salvador Zubirán, Mexico City, Mexico.
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Burgraff NJ, Neumueller SE, Buchholz K, Langer TM, Hodges MR, Pan L, Forster HV. Ventilatory and integrated physiological responses to chronic hypercapnia in goats. J Physiol 2018; 596:5343-5363. [PMID: 30211447 DOI: 10.1113/jp276666] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 09/07/2018] [Indexed: 02/06/2023] Open
Abstract
KEY POINTS Chronic hypercapnia per se has distinct effects on the mechanisms regulating steady-state ventilation and the CO2 /H+ chemoreflex. Chronic hypercapnia leads to sustained hyperpnoea that exceeds predicted ventilation based upon the CO2 /H+ chemoreflex. There is an integrative ventilatory, cardiovascular and metabolic physiological response to chronic hypercapnia. Chronic hypercapnia leads to deterioration of cognitive function. ABSTRACT Respiratory diseases such as chronic obstructive pulmonary disease (COPD) often lead to chronic hypercapnia which may exacerbate progression of the disease, increase risk of mortality and contribute to comorbidities such as cognitive dysfunction. Determining the contribution of hypercapnia per se to adaptations in ventilation and cognitive dysfunction within this patient population is complicated by the presence of multiple comorbidities. Herein, we sought to determine the role of chronic hypercapnia per se on the temporal pattern of ventilation and the ventilatory CO2 /H+ chemoreflex by exposing healthy goats to either room air or an elevated inspired CO2 (InCO2 ) of 6% for 30 days. A second objective was to determine whether chronic hypercapnia per se contributes to cognitive dysfunction. During 30 days of exposure to 6% InCO2 , steady-state (SS) ventilation ( V ̇ I ) initially increased to 335% of control, and then within 1-5 days decreased and stabilized at ∼230% of control. There was an initial respiratory acidosis that was partially mitigated over time due to increased arterial [HCO3 - ]. There was a transient decrease in the ventilatory CO2 /H+ chemoreflex, followed by return to pre-exposure levels. The SS V ̇ I during chronic hypercapnia was greater than predicted from the acute CO2 /H+ chemoreflex, suggesting separate mechanisms regulating SS V ̇ I and the chemoreflex. Finally, as assessed by a shape discrimination test, we found a sustained decrease in cognitive function during chronic hypercapnia. We conclude that chronic hypercapnia per se results in: (1) a disconnect between SS V ̇ I and the CO2 /H+ chemoreflex, and (2) deterioration of cognitive function.
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Affiliation(s)
| | | | - Kirstyn Buchholz
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Thomas M Langer
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA.,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Lawrence Pan
- Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Hubert V Forster
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA.,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, USA.,Zablocki Veterans Affairs Medical Center, Milwaukee, WI, 53226, USA
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40
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Teppema LJ. CrossTalk opposing view: the hypoxic ventilatory response does not include a central, excitatory hypoxia sensing component. J Physiol 2018; 596:2939-2941. [PMID: 29947097 PMCID: PMC6068226 DOI: 10.1113/jp275708] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Luc J. Teppema
- Department of AnaesthesiologyLeiden University Medical CentreLeidenThe Netherlands
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Jonkman K, van Rijnsoever E, Olofsen E, Aarts L, Sarton E, van Velzen M, Niesters M, Dahan A. Esketamine counters opioid-induced respiratory depression. Br J Anaesth 2018; 120:1117-1127. [DOI: 10.1016/j.bja.2018.02.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 02/16/2018] [Accepted: 02/17/2018] [Indexed: 01/09/2023] Open
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Abstract
Abstract
Background
Previous studies integrated opioid benefit and harm into one single function—the utility function—to determine the drug toxicity (respiratory depression) in light of its wanted effect (analgesia). This study further refined the concept of the utility function using the respiratory and analgesic effects of the opioid analgesic alfentanil as example.
Methods
Data from three previous studies in 48 healthy volunteers were combined and reanalyzed using a population pharmacokinetic–pharmacodynamic analysis to create utility probability functions. Four specific conditions were defined: probability of adequate analgesia without severe respiratory depression, probability of adequate analgesia with severe respiratory depression, probability of inadequate analgesia without severe respiratory depression, and probability of inadequate analgesia with severe respiratory depression.
Results
The four conditions were successfully identified with probabilities varying depending on the opioid effect-site concentration. The optimum analgesia probability without serious respiratory depression is reached at an alfentanil effect-site concentration of 68 ng/ml, and exceeds the probability of the most unwanted effect, inadequate analgesia with severe respiratory depression (odds ratio, 4.0). At higher effect-site concentrations the probability of analgesia is reduced and exceeded by the probability of serious respiratory depression.
Conclusions
The utility function was successfully further developed, allowing assessment of specific conditions in terms of wanted and unwanted effects. This approach can be used to compare the toxic effects of drugs relative to their intended effect and may be a useful tool in the development of new compounds to assess their advantage over existing drugs.
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Sacramento JF, Chew DJ, Melo BF, Donegá M, Dopson W, Guarino MP, Robinson A, Prieto-Lloret J, Patel S, Holinski BJ, Ramnarain N, Pikov V, Famm K, Conde SV. Bioelectronic modulation of carotid sinus nerve activity in the rat: a potential therapeutic approach for type 2 diabetes. Diabetologia 2018; 61:700-710. [PMID: 29332196 PMCID: PMC6448966 DOI: 10.1007/s00125-017-4533-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/20/2017] [Indexed: 02/08/2023]
Abstract
AIMS/HYPOTHESIS A new class of treatments termed bioelectronic medicines are now emerging that aim to target individual nerve fibres or specific brain circuits in pathological conditions to repair lost function and reinstate a healthy balance. Carotid sinus nerve (CSN) denervation has been shown to improve glucose homeostasis in insulin-resistant and glucose-intolerant rats; however, these positive effects from surgery appear to diminish over time and are heavily caveated by the severe adverse effects associated with permanent loss of chemosensory function. Herein we characterise the ability of a novel bioelectronic application, classified as kilohertz frequency alternating current (KHFAC) modulation, to suppress neural signals within the CSN of rodents. METHODS Rats were fed either a chow or high-fat/high-sucrose (HFHSu) diet (60% lipid-rich diet plus 35% sucrose drinking water) over 14 weeks. Neural interfaces were bilaterally implanted in the CSNs and attached to an external pulse generator. The rats were then randomised to KHFAC or sham modulation groups. KHFAC modulation variables were defined acutely by respiratory and cardiac responses to hypoxia (10% O2 + 90% N2). Insulin sensitivity was evaluated periodically through an ITT and glucose tolerance by an OGTT. RESULTS KHFAC modulation of the CSN, applied over 9 weeks, restored insulin sensitivity (constant of the insulin tolerance test [KITT] HFHSu sham, 2.56 ± 0.41% glucose/min; KITT HFHSu KHFAC, 5.01 ± 0.52% glucose/min) and glucose tolerance (AUC HFHSu sham, 1278 ± 20.36 mmol/l × min; AUC HFHSu KHFAC, 1054.15 ± 62.64 mmol/l × min) in rat models of type 2 diabetes. Upon cessation of KHFAC, insulin resistance and glucose intolerance returned to normal values within 5 weeks. CONCLUSIONS/INTERPRETATION KHFAC modulation of the CSN improves metabolic control in rat models of type 2 diabetes. These positive outcomes have significant translational potential as a novel therapeutic modality for the purpose of treating metabolic diseases in humans.
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Affiliation(s)
- Joana F Sacramento
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa, Rua Camara Pestana, no. 6, 6A, edificio II, piso 3, 1150-082, Lisboa, Portugal
| | | | - Bernardete F Melo
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa, Rua Camara Pestana, no. 6, 6A, edificio II, piso 3, 1150-082, Lisboa, Portugal
| | | | | | - Maria P Guarino
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa, Rua Camara Pestana, no. 6, 6A, edificio II, piso 3, 1150-082, Lisboa, Portugal
- Escola Superior de Saúde de Leiria-Instituto Politécnico de Leiria, Leiria, Portugal
| | | | - Jesus Prieto-Lloret
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa, Rua Camara Pestana, no. 6, 6A, edificio II, piso 3, 1150-082, Lisboa, Portugal
| | | | | | | | | | | | - Silvia V Conde
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa, Rua Camara Pestana, no. 6, 6A, edificio II, piso 3, 1150-082, Lisboa, Portugal.
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Conde SV, Sacramento JF, Guarino MP. Carotid body: a metabolic sensor implicated in insulin resistance. Physiol Genomics 2018; 50:208-214. [PMID: 29373079 DOI: 10.1152/physiolgenomics.00121.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The carotid body is now looked at as a multipurpose sensor for blood gases, blood pH, and several hormones. The matter of glucose sensing by the carotid body has been debated for several years in the literature, and these days there is a consensus that carotid body activity is modified by metabolic factors that contribute to glucose homeostasis. However, the sensing ability for glucose is still being pondered: are the carotid bodies low glucose sensors or, in contrast, are they overresponsive in high-glucose conditions? Herein, we debate the glucose and insulin sensing capabilities of the carotid body as key early events in the overactivation of the carotid body, which is increasingly recognized as an important feature of metabolic diseases. Additionally, we dedicate a final section to discuss new outside-the-box therapies designed to decrease carotid body activity that may be used for treating metabolic diseases.
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Affiliation(s)
- Silvia V Conde
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa , Lisbon , Portugal
| | - Joana F Sacramento
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa , Lisbon , Portugal
| | - Maria P Guarino
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa , Lisbon , Portugal.,School of Health Sciences, Polytechnic Institute of Leiria , Leiria , Portugal
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Guyenet PG, Bayliss DA, Stornetta RL, Kanbar R, Shi Y, Holloway BB, Souza GMPR, Basting TM, Abbott SBG, Wenker IC. Interdependent feedback regulation of breathing by the carotid bodies and the retrotrapezoid nucleus. J Physiol 2017; 596:3029-3042. [PMID: 29168167 DOI: 10.1113/jp274357] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/02/2017] [Indexed: 12/13/2022] Open
Abstract
The retrotrapezoid nucleus (RTN) regulates breathing in a CO2 - and state-dependent manner. RTN neurons are glutamatergic and innervate principally the respiratory pattern generator; they regulate multiple aspects of breathing, including active expiration, and maintain breathing automaticity during non-REM sleep. RTN neurons encode arterial PCO2 /pH via cell-autonomous and paracrine mechanisms, and via input from other CO2 -responsive neurons. In short, RTN neurons are a pivotal structure for breathing automaticity and arterial PCO2 homeostasis. The carotid bodies stimulate the respiratory pattern generator directly and indirectly by activating RTN via a neuronal projection originating within the solitary tract nucleus. The indirect pathway operates under normo- or hypercapnic conditions; under respiratory alkalosis (e.g. hypoxia) RTN neurons are silent and the excitatory input from the carotid bodies is suppressed. Also, silencing RTN neurons optogenetically quickly triggers a compensatory increase in carotid body activity. Thus, in conscious mammals, breathing is subject to a dual and interdependent feedback regulation by chemoreceptors. Depending on the circumstance, the activity of the carotid bodies and that of RTN vary in the same or the opposite directions, producing additive or countervailing effects on breathing. These interactions are mediated either via changes in blood gases or by brainstem neuronal connections, but their ultimate effect is invariably to minimize arterial PCO2 fluctuations. We discuss the potential relevance of this dual chemoreceptor feedback to cardiorespiratory abnormalities present in diseases in which the carotid bodies are hyperactive at rest, e.g. essential hypertension, obstructive sleep apnoea and heart failure.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Ruth L Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Roy Kanbar
- Department of Pharmaceutical Sciences, Lebanese American University, Beyrouth, Lebanon
| | - Yingtang Shi
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Benjamin B Holloway
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - George M P R Souza
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Tyler M Basting
- Department of Pharmacology & Experimental Therapeutics, Louisiana State University, New Orleans, Louisiana 70112, USA
| | - Stephen B G Abbott
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Ian C Wenker
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
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46
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van der Schrier R, Jonkman K, van Velzen M, Olofsen E, Drewes AM, Dahan A, Niesters M. An experimental study comparing the respiratory effects of tapentadol and oxycodone in healthy volunteers. Br J Anaesth 2017; 119:1169-1177. [DOI: 10.1093/bja/aex295] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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Sheikhbahaei S, Gourine AV, Smith JC. Respiratory rhythm irregularity after carotid body denervation in rats. Respir Physiol Neurobiol 2017; 246:92-97. [PMID: 28782663 PMCID: PMC5637156 DOI: 10.1016/j.resp.2017.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 07/09/2017] [Accepted: 08/01/2017] [Indexed: 12/13/2022]
Abstract
Respiratory activity is controlled by inputs from the peripheral and central chemoreceptors. Since overactivity of the carotid bodies, the main peripheral chemoreceptors, is linked to the pathophysiology of disparate metabolic and cardiovascular diseases, carotid body denervation (CBD) has been proposed as a potential treatment. However, long-term effects of CBD on the respiratory rhythm and regularity of breathing remain unknown. Here, we show that five weeks after bilateral CBD in rats, the respiratory rhythm was slower and less regular. Ten weeks after bilateral CBD, the respiratory frequency was not different from the sham-operated group, but the regularity of the respiratory rhythm was still reduced. Increased frequency of randomly occurring apneas is likely to be responsible for the irregular breathing pattern after CBD. These results should be taken into consideration since any treatment that reduces the stability of the respiratory rhythm might exacerbate the cardio-respiratory instability and worsen the cardiovascular outcomes.
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Affiliation(s)
- Shahriar Sheikhbahaei
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA; Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK.
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK
| | - Jeffrey C Smith
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA
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48
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Parkes MJ. Reappraisal of systemic venous chemoreceptors: might they explain the matching of breathing to metabolic rate in humans? Exp Physiol 2017; 102:1567-1583. [DOI: 10.1113/ep086561] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/07/2017] [Indexed: 12/20/2022]
Affiliation(s)
- M. J. Parkes
- School of Sport, Exercise and Rehabilitation Sciences; University of Birmingham; Edgbaston Birmingham B15 2TT UK
- National Institute for Health Research/Wellcome Trust Birmingham Clinical Research Facility; University Hospitals Birmingham National Health Service Foundation Trust; Birmingham B15 2TH UK
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49
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Tipton MJ, Harper A, Paton JFR, Costello JT. The human ventilatory response to stress: rate or depth? J Physiol 2017. [PMID: 28650070 DOI: 10.1113/jp274596] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Many stressors cause an increase in ventilation in humans. This is predominantly reported as an increase in minute ventilation (V̇E). But, the same V̇E can be achieved by a wide variety of changes in the depth (tidal volume, VT ) and number of breaths (respiratory frequency, ƒR ). This review investigates the impact of stressors including: cold, heat, hypoxia, pain and panic on the contributions of ƒR and VT to V̇E to see if they differ with different stressors. Where possible we also consider the potential mechanisms that underpin the responses identified, and propose mechanisms by which differences in ƒR and VT are mediated. Our aim being to consider if there is an overall differential control of ƒR and VT that applies in a wide range of conditions. We consider moderating factors, including exercise, sex, intensity and duration of stimuli. For the stressors reviewed, as the stress becomes extreme V̇E generally becomes increased more by ƒR than VT . We also present some tentative evidence that the pattern of ƒR and VT could provide some useful diagnostic information for a variety of clinical conditions. In The Physiological Society's year of 'Making Sense of Stress', this review has wide-ranging implications that are not limited to one discipline, but are integrative and relevant for physiology, psychophysiology, neuroscience and pathophysiology.
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Affiliation(s)
- Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK
| | - Abbi Harper
- Clinical Fellow in Intensive Care Medicine, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Julian F R Paton
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University Walk, University of Bristol, Bristol, BS8 1TD, UK
| | - Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK
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50
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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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