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Arce-Álvarez A, Salazar-Ardiles C, Cornejo C, Paez V, Vásquez-Muñoz M, Stillner-Vilches K, Jara CR, Ramirez-Campillo R, Izquierdo M, Andrade DC. Chemoreflex Control as the Cornerstone in Immersion Water Sports: Possible Role on Breath-Hold. Front Physiol 2022; 13:894921. [PMID: 35733994 PMCID: PMC9207453 DOI: 10.3389/fphys.2022.894921] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 05/10/2022] [Indexed: 11/30/2022] Open
Abstract
Immersion water sports involve long-term apneas; therefore, athletes must physiologically adapt to maintain muscle oxygenation, despite not performing pulmonary ventilation. Breath-holding (i.e., apnea) is common in water sports, and it involves a decrease and increases PaO2 and PaCO2, respectively, as the primary signals that trigger the end of apnea. The principal physiological O2 sensors are the carotid bodies, which are able to detect arterial gases and metabolic alterations before reaching the brain, which aids in adjusting the cardiorespiratory system. Moreover, the principal H+/CO2 sensor is the retrotrapezoid nucleus, which is located at the brainstem level; this mechanism contributes to detecting respiratory and metabolic acidosis. Although these sensors have been characterized in pathophysiological states, current evidence shows a possible role for these mechanisms as physiological sensors during voluntary apnea. Divers and swimmer athletes have been found to displayed longer apnea times than land sports athletes, as well as decreased peripheral O2 and central CO2 chemoreflex control. However, although chemosensitivity at rest could be decreased, we recently found marked sympathoexcitation during maximum voluntary apnea in young swimmers, which could activate the spleen (which is a reservoir organ for oxygenated blood). Therefore, it is possible that the chemoreflex, autonomic function, and storage/delivery oxygen organ(s) are linked to apnea in immersion water sports. In this review, we summarized the available evidence related to chemoreflex control in immersion water sports. Subsequently, we propose a possible physiological mechanistic model that could contribute to providing new avenues for understanding the respiratory physiology of water sports.
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Affiliation(s)
- Alexis Arce-Álvarez
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de La Salud, Universidad de Antofagasta, Antofagasta, Chile
- Escuela de Kinesiología, Facultad de Salud, Universidad Católica Silva Henríquez, Santiago, Chile
- Navarrabiomed, Hospital Universitario de Navarra (CHN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain
| | - Camila Salazar-Ardiles
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de La Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Carlos Cornejo
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de La Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Valeria Paez
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de La Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Manuel Vásquez-Muñoz
- Navarrabiomed, Hospital Universitario de Navarra (CHN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain
- Clínica Santa María, Santiago, Chile
| | | | - Catherine R. Jara
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de La Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Rodrigo Ramirez-Campillo
- Exercise and Rehabilitation Sciences Laboratory, School of Physical Therapy, Faculty of Rehabilitation Sciences, Universidad Andres Bello, Santiago, Chile
| | - Mikel Izquierdo
- Navarrabiomed, Hospital Universitario de Navarra (CHN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain
| | - David C. Andrade
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de La Salud, Universidad de Antofagasta, Antofagasta, Chile
- *Correspondence: David C. Andrade, ,
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Cinelli E, Mutolo D, Pantaleo T, Bongianni F. Neural mechanisms underlying respiratory regulation within the preBötzinger complex of the rabbit. Respir Physiol Neurobiol 2021; 293:103736. [PMID: 34224867 DOI: 10.1016/j.resp.2021.103736] [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] [Received: 03/08/2021] [Revised: 07/01/2021] [Accepted: 07/01/2021] [Indexed: 11/29/2022]
Abstract
The preBötzinger complex (preBötC) is a medullary area essential for normal breathing and widely recognized as necessary and sufficient to generate the inspiratory phase of respiration. It has been studied mainly in rodents. Here we report the main results of our studies revealing the characteristics of the rabbit preBötC identified by means of neuronal recordings, D,L-homocysteic acid microinjections and histological controls. A crucial role in the respiratory rhythmogenesis within this neural substrate is played by excitatory amino acids, but also GABA and glycine display important contributions. Increases in respiratory frequency are induced by microinjections of neurokinins, somatostatin as well by serotonin (5-HT) through an action on 5-HT1A and 5-HT3 receptors or the disinhibition of a GABAergic circuit. Respiratory depression is observed in response to microinjections of the μ-opioid receptor agonist DAMGO. Our results show similarities and differences with the rodent preBötC and emphasize the importance of comparative studies on the mechanisms underlying respiratory rhythmogenesis in different animal species.
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Affiliation(s)
- Elenia Cinelli
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università Degli Studi di Firenze, Viale G.B. Morgagni 63, Firenze, 50134, Italy
| | - Donatella Mutolo
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università Degli Studi di Firenze, Viale G.B. Morgagni 63, Firenze, 50134, Italy
| | - Tito Pantaleo
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università Degli Studi di Firenze, Viale G.B. Morgagni 63, Firenze, 50134, Italy
| | - Fulvia Bongianni
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università Degli Studi di Firenze, Viale G.B. Morgagni 63, Firenze, 50134, Italy.
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Quintero MC, Putnam RW, Cordovez JM. Theoretical perspectives on central chemosensitivity: CO2/H+-sensitive neurons in the locus coeruleus. PLoS Comput Biol 2017; 13:e1005853. [PMID: 29267284 PMCID: PMC5755939 DOI: 10.1371/journal.pcbi.1005853] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 01/05/2018] [Accepted: 10/26/2017] [Indexed: 12/18/2022] Open
Abstract
Central chemoreceptors are highly sensitive neurons that respond to changes in pH and CO2 levels. An increase in CO2/H+ typically reflects a rise in the firing rate of these neurons, which stimulates an increase in ventilation. Here, we present an ionic current model that reproduces the basic electrophysiological activity of individual CO2/H+-sensitive neurons from the locus coeruleus (LC). We used this model to explore chemoreceptor discharge patterns in response to electrical and chemical stimuli. The modeled neurons showed both stimulus-evoked activity and spontaneous activity under physiological parameters. Neuronal responses to electrical and chemical stimulation showed specific firing patterns of spike frequency adaptation, postinhibitory rebound, and post-stimulation recovery. Conversely, the response to chemical stimulation alone (based on physiological CO2/H+ changes), in the absence of external depolarizing stimulation, showed no signs of postinhibitory rebound or post-stimulation recovery, and no depolarizing sag. A sensitivity analysis for the firing-rate response to the different stimuli revealed that the contribution of an applied stimulus current exceeded that of the chemical signals. The firing-rate response increased indefinitely with injected depolarizing current, but reached saturation with chemical stimuli. Our computational model reproduced the regular pacemaker-like spiking pattern, action potential shape, and most of the membrane properties that characterize CO2/H+-sensitive neurons from the locus coeruleus. This validates the model and highlights its potential as a tool for studying the cellular mechanisms underlying the altered central chemosensitivity present in a variety of disorders such as sudden infant death syndrome, depression, and anxiety. In addition, the model results suggest that small external electrical signals play a greater role in determining the chemosensitive response to changes in CO2/H+ than previously thought. This highlights the importance of considering electrical synaptic transmission in studies of intrinsic chemosensitivity. The sensory mechanism by which changes in CO2 and H+ levels are detected in the brain is known as central chemoreception. Altered chemoreception is common to a wide variety of clinical conditions, including sleep apnea, sudden infant death syndrome, hyperventilation, depression, anxiety and asthma. In addition, CO2/H+-sensitive neurons are present in some regions of the brain that have been identified as drug targets for the treatment of anxiety and panic disorders. We are interested in understanding the cellular mechanisms that determine and modulate the behavior of these neurons. We previously investigated possible mechanisms underlying their behavior in rats to elucidate whether they respond to changes in intracellular or extracellular pH, CO2, or a combination of these stimuli. To study the roles that signals and ion channel targets play in individual neurons we develop mathematical models that simulate their electrochemical behavior and their responses to hypercapnic and/or acidotic stimuli. Nowadays, we are focused on using computational tools to explore the firing pattern of such neurons in response to chemical (CO2/H+) and electrical (synaptic) stimulation. Our results reveal significant effects of electrical stimulation on the responses of brainstem neurons and highlight the importance of considering synaptic transmission in experimental studies of chemosensitivity.
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Affiliation(s)
- Maria C. Quintero
- Biomedical Engineering Department, Universidad de Los Andes, Bogotá, Colombia
- * E-mail: (MQ); (JC)
| | - Robert W. Putnam
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, United States of America
| | - Juan M. Cordovez
- Biomedical Engineering Department, Universidad de Los Andes, Bogotá, Colombia
- * E-mail: (MQ); (JC)
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Toledo C, Andrade DC, Lucero C, Schultz HD, Marcus N, Retamal M, Madrid C, Del Rio R. Contribution of peripheral and central chemoreceptors to sympatho-excitation in heart failure. J Physiol 2016; 595:43-51. [PMID: 27218485 DOI: 10.1113/jp272075] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/20/2016] [Indexed: 12/18/2022] Open
Abstract
Chronic heart failure (CHF) is a major public health problem. Tonic hyper-activation of sympathetic neural outflow is commonly observed in patients with CHF. Importantly, sympatho-excitation in CHF exacerbates its progression and is strongly related to poor prognosis and high mortality risk. Increases in both peripheral and central chemoreflex drive are considered markers of the severity of CHF. The principal peripheral chemoreceptors are the carotid bodies (CBs) and alteration in their function has been described in CHF. Mainly, during CHF the CB chemosensitivity is enhanced leading to increases in ventilation and sympathetic outflow. In addition to peripheral control of breathing, central chemoreceptors (CCs) are considered a dominant mechanism in ventilatory regulation. Potentiation of the ventilatory and sympathetic drive in response to CC activation has been shown in patients with CHF as well as in animal models. Therefore, improving understanding of the contribution of the peripheral and central chemoreflexes to augmented sympathetic discharge in CHF could help in developing new therapeutic approaches intended to attenuate the progression of CHF. Accordingly, the main focus of this review is to discuss recent evidence that peripheral and central chemoreflex function are altered in CHF and that they contribute to autonomic imbalance and progression of CHF.
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Affiliation(s)
- Camilo Toledo
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
| | - David C Andrade
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
| | - Claudia Lucero
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
| | - Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Noah Marcus
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, IA, USA
| | - Mauricio Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile
| | - Carlos Madrid
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
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Jones SE, Dutschmann M. Testing the hypothesis of neurodegeneracy in respiratory network function with a priori transected arterially perfused brain stem preparation of rat. J Neurophysiol 2016; 115:2593-607. [PMID: 26888109 DOI: 10.1152/jn.01073.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/12/2016] [Indexed: 11/22/2022] Open
Abstract
Degeneracy of respiratory network function would imply that anatomically discrete aspects of the brain stem are capable of producing respiratory rhythm. To test this theory we a priori transected brain stem preparations before reperfusion and reoxygenation at 4 rostrocaudal levels: 1.5 mm caudal to obex (n = 5), at obex (n = 5), and 1.5 (n = 7) and 3 mm (n = 6) rostral to obex. The respiratory activity of these preparations was assessed via recordings of phrenic and vagal nerves and lumbar spinal expiratory motor output. Preparations with a priori transection at level of the caudal brain stem did not produce stable rhythmic respiratory bursting, even when the arterial chemoreceptors were stimulated with sodium cyanide (NaCN). Reperfusion of brain stems that preserved the pre-Bötzinger complex (pre-BötC) showed spontaneous and sustained rhythmic respiratory bursting at low phrenic nerve activity (PNA) amplitude that occurred simultaneously in all respiratory motor outputs. We refer to this rhythm as the pre-BötC burstlet-type rhythm. Conserving circuitry up to the pontomedullary junction consistently produced robust high-amplitude PNA at lower burst rates, whereas sequential motor patterning across the respiratory motor outputs remained absent. Some of the rostrally transected preparations expressed both burstlet-type and regular PNA amplitude rhythms. Further analysis showed that the burstlet-type rhythm and high-amplitude PNA had 1:2 quantal relation, with burstlets appearing to trigger high-amplitude bursts. We conclude that no degenerate rhythmogenic circuits are located in the caudal medulla oblongata and confirm the pre-BötC as the primary rhythmogenic kernel. The absence of sequential motor patterning in a priori transected preparations suggests that pontine circuits govern respiratory pattern formation.
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Affiliation(s)
- Sarah E Jones
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
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Dorsal and ventral aspects of the most caudal medullary reticular formation have differential roles in modulation and formation of the respiratory motor pattern in rat. Brain Struct Funct 2015; 221:4353-4368. [DOI: 10.1007/s00429-015-1165-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 11/26/2015] [Indexed: 11/24/2022]
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Garg SK, Lioy DT, Knopp SJ, Bissonnette JM. Conditional depletion of methyl-CpG-binding protein 2 in astrocytes depresses the hypercapnic ventilatory response in mice. J Appl Physiol (1985) 2015. [DOI: 10.1152/japplphysiol.00411.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mice that are deficient in the transcription factor methyl-CpG-binding protein 2 (MeCP2) have a depressed hypercapnic ventilatory response (HCVR). The expression of MeCP2 can be selectively removed from astrocytes or neurons, thus offering a tool to dissect the role of this transcription factor in astrocytes from that in neurons. Studies were carried out in the progeny of mice that were a cross between those harboring a tamoxifen (TAM)-inducible Cre recombinase transgene driven by the human astrocytic glial fibrillary acidic protein (hGFAP) promoter, or Cre recombinase under control of the synapsin promoter, with mice containing a Cre-excisable exon III in the Mecp2 gene. The TAM-conditional excision of the Mecp2 exon allowed the respiratory CO2 response to be studied in the same animals before and after selective depletion of MeCP2 in astrocytes. Immunohistochemistry showed that following TAM treatment only ∼20% of GFAP-labeled cells in the retrotrapazoid nucleus and in the raphé magnus were positive for MeCP2. The slope of the relative increase in minute ventilation as a function of 1, 3, and 5% inspired CO2 was depressed in mice with depleted astrocyte MeCP2 compared with wild-type littermates. In contrast, selective depletion of MeCP2 in neurons did not significantly affect slope. While neurons which constitute the respiratory network ultimately determine the ventilatory response to CO2, this study demonstrates that loss of MeCP2 in astrocytes alone is sufficient to result in a dramatic attenuation of the HCVR. We propose that the glial contribution to HCVR is under the control of the MeCP2 gene.
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Affiliation(s)
| | | | | | - John M. Bissonnette
- Department of Obstetrics and Gynecology, and
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, Oregon
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From the Journal archives: Assessing the effect of anesthetic agents on the respiratory chemoreflex control of breathing. Can J Anaesth 2014; 61:664-70. [DOI: 10.1007/s12630-014-0110-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 01/07/2014] [Indexed: 10/25/2022] Open
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Huang WH, Tupal S, Huang TW, Ward CS, Neul JL, Klisch TJ, Gray PA, Zoghbi HY. Atoh1 governs the migration of postmitotic neurons that shape respiratory effectiveness at birth and chemoresponsiveness in adulthood. Neuron 2012; 75:799-809. [PMID: 22958821 PMCID: PMC3464459 DOI: 10.1016/j.neuron.2012.06.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/25/2012] [Indexed: 10/27/2022]
Abstract
Hindbrain neuronal networks serving respiratory, proprioceptive, and arousal functions share a developmental requirement for the bHLH transcription factor Atoh1. Loss of Atoh1 in mice results in respiratory failure and neonatal lethality; however, the neuronal identity and mechanism by which Atoh1-dependent cells sustain newborn breathing remains unknown. We uncovered that selective loss of Atoh1 from the postmitotic retrotrapezoid nucleus (RTN) neurons results in severely impaired inspiratory rhythm and pronounced neonatal death. Mice that escape neonatal death develop abnormal chemoresponsiveness as adults. Interestingly, the expression of Atoh1 in the RTN neurons is not required for their specification or maintenance, but is important for their proper localization and to establish essential connections with the preBötzinger Complex (preBötC). These results provide insights into the genetic regulation of neonatal breathing and shed light on the labile sites that might contribute to sudden death in newborn infants and altered chemoresponsiveness in adults.
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Affiliation(s)
- Wei-Hsiang Huang
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
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