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Krnić J, Madirazza K, Pecotić R, Benzon B, Carev M, Đogaš Z. The Effects of Volatile Anesthetics on Renal Sympathetic and Phrenic Nerve Activity during Acute Intermittent Hypoxia in Rats. Biomedicines 2024; 12:910. [PMID: 38672264 PMCID: PMC11048470 DOI: 10.3390/biomedicines12040910] [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: 03/20/2024] [Revised: 04/07/2024] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
Coordinated activation of sympathetic and respiratory nervous systems is crucial in responses to noxious stimuli such as intermittent hypoxia. Acute intermittent hypoxia (AIH) is a valuable model for studying obstructive sleep apnea (OSA) pathophysiology, and stimulation of breathing during AIH is known to elicit long-term changes in respiratory and sympathetic functions. The aim of this study was to record the renal sympathetic nerve activity (RSNA) and phrenic nerve activity (PNA) during the AIH protocol in rats exposed to monoanesthesia with sevoflurane or isoflurane. Adult male Sprague-Dawley rats (n = 24; weight: 280-360 g) were selected and randomly divided into three groups: two experimental groups (sevoflurane group, n = 6; isoflurane group, n = 6) and a control group (urethane group, n = 12). The AIH protocol was identical in all studied groups and consisted in delivering five 3 min-long hypoxic episodes (fraction of inspired oxygen, FiO2 = 0.09), separated by 3 min recovery intervals at FiO2 = 0.5. Volatile anesthetics, isoflurane and sevoflurane, blunted the RSNA response to AIH in comparison to urethane anesthesia. Additionally, the PNA response to acute intermittent hypoxia was preserved, indicating that the respiratory system might be more robust than the sympathetic system response during exposure to acute intermittent hypoxia.
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Affiliation(s)
- Josip Krnić
- Department of Emergency Medicine, University Hospital of Split, Spinčićeva 1, 21000 Split, Croatia
- Department of Anesthesiology, Reanimatology and Intensive Care Medicine, University Hospital of Split, Spinčićeva 1, 21000 Split, Croatia
| | - Katarina Madirazza
- Department of Neuroscience, University of Split School of Medicine, Šoltanska 2A, 21000 Split, Croatia
| | - Renata Pecotić
- Department of Neuroscience, University of Split School of Medicine, Šoltanska 2A, 21000 Split, Croatia
| | - Benjamin Benzon
- Department of Anatomy, University of Split School of Medicine, Šoltanska 2A, 21000 Split, Croatia
| | - Mladen Carev
- Department of Anesthesiology, Reanimatology and Intensive Care Medicine, University Hospital of Split, Spinčićeva 1, 21000 Split, Croatia
| | - Zoran Đogaš
- Department of Neuroscience, University of Split School of Medicine, Šoltanska 2A, 21000 Split, Croatia
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Madirazza K, Pecotic R, Pavlinac Dodig I, Valic M, Dogas Z. Blockade of alpha2-adrenergic receptors in the caudal raphe region enhances the renal sympathetic nerve activity response to acute intermittent hypercapnia in rats. Physiol Res 2022; 71:159-169. [PMID: 35043650 DOI: 10.33549/physiolres.934717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The study investigated the role of alpha2-adrenergic receptors of the caudal raphe region in the sympathetic and cardiovascular responses to the acute intermittent hypercapnia (AIHc). Urethane-anesthetized, vagotomized, mechanically ventilated Sprague-Dawley rats (n=38) were exposed to the AIHc protocol (5×3 min, 15 % CO2+50 % O2) in hyperoxic background (50 % O2). alpha2-adrenergic receptor antagonist-yohimbine was applied intravenously (1 mg/kg, n=9) or microinjected into the caudal raphe region (2 mM, n=12) prior to exposure to AIHc. Control groups of animals received saline intravenously (n=7) or into the caudal raphe region (n=10) prior to exposure to AIHc. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP) and heart rate (HR) were monitored before exposure to the AIHc protocol (T0), during five hypercapnic episodes (THc1-5) and at 15 min following the end of the last hypercapnic episode (T15). Following intravenous administration of yohimbine, RSNA was significantly greater during THc1-5 and at T15 than in the control group (P<0.05). When yohimbine was microinjected into the caudal raphe region, AIHc elicited greater increases in RSNA during THc1-5 when compared to the controls (THc1: 138.0+/-4.0 % vs. 123.7+/-4.8 %, P=0.032; THc2: 137.1+/-5.0 % vs. 124.1+/-4.5 %, P=0.071; THc3: 143.1+/-6.4 % vs. 122.0±4.8 %, P=0.020; THc4: 146.1+/-6.2 % vs. 120.7+/-5.7 %, P=0.007 and THc5: 143.2+/-7.7 % vs. 119.2+/-7.2 %, P=0.038). During THc1-5, significant decreases in HR from T0 were observed in all groups, while changes in MAP were observed in the group that received yohimbine intravenously. These findings suggest that blockade of the alpha2-adrenegic receptors in the caudal raphe region might have an important role in sympathetic responses to AIHc.
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Affiliation(s)
- K Madirazza
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia.
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3
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Randelman M, Zholudeva LV, Vinit S, Lane MA. Respiratory Training and Plasticity After Cervical Spinal Cord Injury. Front Cell Neurosci 2021; 15:700821. [PMID: 34621156 PMCID: PMC8490715 DOI: 10.3389/fncel.2021.700821] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 08/11/2021] [Indexed: 12/30/2022] Open
Abstract
While spinal cord injuries (SCIs) result in a vast array of functional deficits, many of which are life threatening, the majority of SCIs are anatomically incomplete. Spared neural pathways contribute to functional and anatomical neuroplasticity that can occur spontaneously, or can be harnessed using rehabilitative, electrophysiological, or pharmacological strategies. With a focus on respiratory networks that are affected by cervical level SCI, the present review summarizes how non-invasive respiratory treatments can be used to harness this neuroplastic potential and enhance long-term recovery. Specific attention is given to "respiratory training" strategies currently used clinically (e.g., strength training) and those being developed through pre-clinical and early clinical testing [e.g., intermittent chemical stimulation via altering inhaled oxygen (hypoxia) or carbon dioxide stimulation]. Consideration is also given to the effect of training on non-respiratory (e.g., locomotor) networks. This review highlights advances in this area of pre-clinical and translational research, with insight into future directions for enhancing plasticity and improving functional outcomes after SCI.
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Affiliation(s)
- Margo Randelman
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.,Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Lyandysha V Zholudeva
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.,Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States.,Gladstone Institutes, San Francisco, CA, United States
| | - Stéphane Vinit
- INSERM, END-ICAP, Université Paris-Saclay, UVSQ, Versailles, France
| | - Michael A Lane
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.,Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
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Puri S, Panza G, Mateika JH. A comprehensive review of respiratory, autonomic and cardiovascular responses to intermittent hypoxia in humans. Exp Neurol 2021; 341:113709. [PMID: 33781731 PMCID: PMC8527806 DOI: 10.1016/j.expneurol.2021.113709] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/17/2021] [Accepted: 03/24/2021] [Indexed: 01/08/2023]
Abstract
This review explores forms of respiratory and autonomic plasticity, and associated outcome measures, that are initiated by exposure to intermittent hypoxia. The review focuses primarily on studies that have been completed in humans and primarily explores the impact of mild intermittent hypoxia on outcome measures. Studies that have explored two forms of respiratory plasticity, progressive augmentation of the hypoxic ventilatory response and long-term facilitation of ventilation and upper airway muscle activity, are initially reviewed. The role these forms of plasticity might have in sleep disordered breathing are also explored. Thereafter, the role of intermittent hypoxia in the initiation of autonomic plasticity is reviewed and the role this form of plasticity has in cardiovascular and hemodynamic responses during and following intermittent hypoxia is addressed. The role of these responses in individuals with sleep disordered breathing and spinal cord injury are subsequently addressed. Ultimately an integrated picture of the respiratory, autonomic and cardiovascular responses to intermittent hypoxia is presented. The goal of the integrated picture is to address the types of responses that one might expect in humans exposed to one-time and repeated daily exposure to mild intermittent hypoxia. This form of intermittent hypoxia is highlighted because of its potential therapeutic impact in promoting functional improvement and recovery in several physiological systems.
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Affiliation(s)
- Shipra Puri
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States of America; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States of America
| | - Gino Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States of America; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States of America
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States of America; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States of America; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States of America.
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Lin MT, Vinit S, Lee KZ. Functional role of carbon dioxide on intermittent hypoxia induced respiratory response following mid-cervical contusion in the rat. Exp Neurol 2021; 339:113610. [PMID: 33453216 DOI: 10.1016/j.expneurol.2021.113610] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/17/2020] [Accepted: 01/09/2021] [Indexed: 12/11/2022]
Abstract
Intermittent hypoxia induces respiratory neuroplasticity to enhance respiratory motor outputs and is a potential rehabilitative strategy to improve respiratory function following cervical spinal injury. The present study was designed to evaluate the functional role of intermittent and sustained carbon dioxide (CO2) on intermittent hypoxia-induced ventilatory responses in rats with mid-cervical spinal contusion. The breathing pattern of unanesthetized rats at the subchronic and chronic injured stages was measured in response to one of the following treatments: (1) Intermittent hypercapnic-hypoxia (10 × 5 min 10%O2 + 4%CO2 with 5 min normoxia interval); (2) Intermittent hypoxia with sustained hypercapnia (10 × 5 min 10%O2 + 4%CO2 with 5 min 21%O2 + 4%CO2 interval); (3) Intermittent hypoxia (10 × 5 min 10%O2 with 5 min normoxia interval); (4) Intermittent hypercapnia (10 × 5 min 21%O2 + 4%CO2 with 5 min normoxia interval); (5) Sustained hypercapnia (100 min, 21% O2 + 4% CO2); (6) Sustained normoxia (100 min, 21% O2). The results demonstrated that intermittent hypoxia associated with intermittent hypercapnia or sustained hypercapnia induced a greater ventilatory response than sustained hypercapnia during stimulus exposure. The tidal volume was significantly enhanced to a similar magnitude following intermittent hypercapnic-hypoxia, intermittent hypoxia with sustained hypercapnia, and intermittent hypoxia in subchronically injured animals; however, only intermittent hypercapnic-hypoxia and intermittent hypoxia were able to evoke long-term facilitation of the tidal volume at the chronic injured stage. These results suggest that mild intermittent hypercapnia did not further enhance the therapeutic effectiveness of intermittent hypoxia-induced respiratory recovery in mid-cervical contused animals. However, sustained hypercapnia associated with intermittent hypoxia may blunt ventilatory responses following intermittent hypoxia at the chronic injured stage.
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Affiliation(s)
- Mei-Tsen Lin
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Stéphane Vinit
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan; Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.
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Gauda EB, McLemore GL. Premature birth, homeostatic plasticity and respiratory consequences of inflammation. Respir Physiol Neurobiol 2019; 274:103337. [PMID: 31733340 DOI: 10.1016/j.resp.2019.103337] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/11/2019] [Accepted: 11/10/2019] [Indexed: 12/23/2022]
Abstract
Infants who are born premature can have persistent apnea beyond term gestation, reemergence of apnea associated with inflammation during infancy, increased risk of sudden unexplained death, and sleep disorder breathing during infancy and childhood. The autonomic nervous system, particularly the central neural networks that control breathing and peripheral and central chemoreceptors and mechanoreceptors that modulate the activity of the central respiratory network, are rapidly developing during the last trimester (22-37 weeks gestation) of fetal life. With advances in neonatology, in well-resourced, developed countries, infants born as young as 23 weeks gestation can survive. Thus, a substantial part of maturation of central and peripheral systems that control breathing occurs ex-utero in infants born at the limit of viability. The balance of excitatory and inhibitory influences dictates the ultimate output from the central respiratory network. We propose in this review that simply being born early in the last trimester can trigger homeostatic plasticity within the respiratory network tipping the balance toward inhibition that persists in infancy. We discuss the intersection of premature birth, homeostatic plasticity and biological mechanisms leading to respiratory depression during inflammation in former premature infants.
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Affiliation(s)
- Estelle B Gauda
- The Hospital for Sick Children, Division of Neonatology, Department of Pediatrics, University of Toronto, Toronto, Ontario, M5G 1X8, Canada.
| | - Gabrielle L McLemore
- Department of Biology, School of Computer, Mathematics and Natural Sciences (SCMNS), Morgan State University, Baltimore, MD, 21251, United States
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Wen MH, Wu MJ, Vinit S, Lee KZ. Modulation of Serotonin and Adenosine 2A Receptors on Intermittent Hypoxia-Induced Respiratory Recovery following Mid-Cervical Contusion in the Rat. J Neurotrauma 2019; 36:2991-3004. [PMID: 31099299 DOI: 10.1089/neu.2018.6371] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The present study was designed to evaluate the therapeutic effectiveness and mechanism of acute intermittent hypoxia on respiratory function at distinct injury stages following mid-cervical spinal contusion. In the first experiment, adult male rats received laminectomy or unilateral contusion at 3rd-4th cervical spinal cord at 9 weeks of age. The ventilatory behavior in response to mild acute intermittent hypercapnic-hypoxia (10 episodes of 5 min of hypoxia [10% O2, 4% CO2, 86% N2] with 5 min of normoxia intervals) was measured by whole-body plethysmography at the acute (∼3 days), subchronic (∼2 weeks), and chronic (∼8 weeks) injury stages. The minute ventilation of contused animals is significantly enhanced following acute intermittent hypercapnic-hypoxia due to an augmentation of the tidal volume at all time-points post-injury. However, acute intermittent hypercapnia-hypoxia-induced ventilatory long-term facilitation was only observed in uninjured animals at the acute stage. During the second experiment, the effect of acute intermittent hypercapnic-hypoxia on respiration was examined in contused animals after a blockade of serotonin receptors, or adenosine 2A receptors. The results demonstrated that acute intermittent hypercapnic-hypoxia-induced enhancement of minute ventilation was attenuated by a serotonin receptor antagonist (methysergide) but enhanced by an adenosine 2A receptor antagonist (KW6002) at the subchronic and chronic injury stages. These results suggested that acute intermittent hypercapnic-hypoxia can induce respiratory recovery from acute to chronic injury stages. The therapeutic effectiveness of intermittent hypercapnic-hypoxia is dampened by the inhibition of serotonin receptors, but a blockade of adenosine 2A receptors enhanced respiratory recovery induced by intermittent hypercapnic-hypoxia.
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Affiliation(s)
- Ming-Han Wen
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Ming-Jane Wu
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Stéphane Vinit
- Université de Versailles Saint-Quentin-en-Yvelines, INSERM U1179 END-ICAP, UFR des Sciences de la Santé-Simone Veil, Montigny-le-Bretonneux, France
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan.,Center for Neuroscience, National Sun Yat-sen University, Kaohsiung, Taiwan.,Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, Taiwan.,Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, Taiwan
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8
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Stipica Safic I, Pecotic R, Pavlinac Dodig I, Dogas Z, Valic Z, Valic M. Phrenic long-term depression evoked by intermittent hypercapnia is modulated by serotonergic and adrenergic receptors in raphe nuclei. J Neurophysiol 2018; 120:321-329. [DOI: 10.1152/jn.00776.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intermittent hypercapnia evokes prolonged depression of phrenic nerve activity (phrenic long-term depression, pLTD). This study was undertaken to investigate the role of 5-HT and α2-adrenergic receptors in the initiation of pLTD. Adult male urethane-anesthetized, vagotomized, paralyzed, and mechanically ventilated Sprague-Dawley rats were exposed to a protocol of acute intermittent hypercapnia (AIHc; 5 episodes of 15% CO2in air, each episode lasting 3 min). The experimental group received microinjection of the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT), the broad-spectrum 5-HT antagonist methysergide, or the α2-adrenergic antagonist yohimbine, whereas the control group received microinjection of 0.9% saline into the caudal raphe region. Peak phrenic nerve activity (pPNA) and burst frequency ( f) were analyzed during baseline (T0), during 5 hypercapnic episodes (THc1–THc5), and at 15, 30, and 60 min after the end of the last hypercapnic episode. In the control group, pPNA decreased 60 min after the end of the last hypercapnic episode compared with baseline values, i.e., pLTD developed ( P = 0.023). In the 8-OH-DPAT group, pPNA significantly decreased at T15, T30, and T60 compared with baseline values, i.e., pLTD developed ( P = 0.01). In the methysergide and yohimbine groups, AIHc did not evoke significant changes of the pPNA at T15, T30, and T60 compared with baseline values. In conclusion, activation of 5-HT1Areceptors accentuated induction of pLTD, whereas blockade of α2-adrenergic receptors prevented development of pLTD following AIHc in anesthetized rats. These results suggest that chemical modulation of 5-HT and α2-adrenergic receptors in raphe nuclei affects hypercapnia-induced pLTD, offering important insights in understanding the mechanisms involved in development of respiratory plasticity.NEW & NOTEWORTHY Hypercapnia is a concomitant feature of many breathing disorders, including obstructive sleep apnea. In this study, acute intermittent hypercapnia evoked development of phrenic long-term depression (pLTD) 60 min after the last hypercapnic episode that was preserved if the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide was microinjected in the caudal raphe region before the hypercapnic stimulus. This study highlights that both 5-HT and adrenergic receptor activation is needed for induction of pLTD in urethane-anesthetized rats following intermittent hypercapnia exposure.
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Affiliation(s)
- Ivona Stipica Safic
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Renata Pecotic
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Ivana Pavlinac Dodig
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Zoran Dogas
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Zoran Valic
- Department of Physiology, University of Split School of Medicine, Split, Croatia
| | - Maja Valic
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
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Mateika JH, Panza G, Alex R, El-Chami M. The impact of intermittent or sustained carbon dioxide on intermittent hypoxia initiated respiratory plasticity. What is the effect of these combined stimuli on apnea severity? Respir Physiol Neurobiol 2017; 256:58-66. [PMID: 29097171 DOI: 10.1016/j.resp.2017.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 10/13/2017] [Accepted: 10/21/2017] [Indexed: 11/28/2022]
Abstract
The following review explores the effect that intermittent or sustained hypercapnia coupled to intermittent hypoxia has on respiratory plasticity. The review explores published work which suggests that intermittent hypercapnia leads to long-term depression of respiration when administered in isolation and prevents the initiation of long-term facilitation when administered in combination with intermittent hypoxia. The review also explores the impact that sustained hypercapnia alone and in combination with intermittent hypoxia has on the magnitude of long-term facilitation. After exploring the outcomes linked to intermittent hypoxia/hypercapnia and intermittent hypoxia/sustained hypercapnia the translational relevance of the outcomes as it relates to breathing stability during sleep is addressed. The likelihood that naturally induced cycles of intermittent hypoxia, coupled to oscillations in carbon dioxide that range between hypocapnia and hypercapnia, do not initiate long-term facilitation is addressed. Moreover, the conditions under which intermittent hypoxia/sustained hypercapnia could serve to improve breathing stability and mitigate co-morbidities associated with sleep apnea are considered.
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Affiliation(s)
- Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, United States.
| | - Gino Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
| | - Raichel Alex
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
| | - Mohamad El-Chami
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
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Deacon NL, McEvoy RD, Stadler DL, Catcheside PG. Intermittent hypercapnic hypoxia during sleep does not induce ventilatory long-term facilitation in healthy males. J Appl Physiol (1985) 2017; 123:534-543. [DOI: 10.1152/japplphysiol.01005.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 06/13/2017] [Accepted: 06/13/2017] [Indexed: 11/22/2022] Open
Abstract
Intermittent hypoxia-induced ventilatory neuroplasticity is likely important in obstructive sleep apnea pathophysiology. Although concomitant CO2levels and arousal state critically influence neuroplastic effects of intermittent hypoxia, no studies have investigated intermittent hypercapnic hypoxia effects during sleep in humans. Thus the purpose of this study was to investigate if intermittent hypercapnic hypoxia during sleep induces neuroplasticity (ventilatory long-term facilitation and increased chemoreflex responsiveness) in humans. Twelve healthy males were exposed to intermittent hypercapnic hypoxia (24 × 30 s episodes of 3% CO2and 3.0 ± 0.2% O2) and intermittent medical air during sleep after 2 wk washout period in a randomized crossover study design. Minute ventilation, end-tidal CO2, O2saturation, breath timing, upper airway resistance, and genioglossal and diaphragm electromyograms were examined during 10 min of stable stage 2 sleep preceding gas exposure, during gas and intervening room air periods, and throughout 1 h of room air recovery. There were no significant differences between conditions across time to indicate long-term facilitation of ventilation, genioglossal or diaphragm electromyogram activity, and no change in ventilatory response from the first to last gas exposure to suggest any change in chemoreflex responsiveness. These findings contrast with previous intermittent hypoxia studies without intermittent hypercapnia and suggest that the more relevant gas disturbance stimulus of concomitant intermittent hypercapnia frequently occurring in sleep apnea influences acute neuroplastic effects of intermittent hypoxia. These findings highlight the need for further studies of intermittent hypercapnic hypoxia during sleep to clarify the role of ventilatory neuroplasticity in the pathophysiology of sleep apnea.NEW & NOTEWORTHY Both arousal state and concomitant CO2levels are known modulators of the effects of intermittent hypoxia on ventilatory neuroplasticity. This is the first study to investigate the effects of combined intermittent hypercapnic hypoxia during sleep in humans. The lack of neuroplastic effects suggests a need for further studies more closely replicating obstructive sleep apnea to determine the pathophysiological relevance of intermittent hypoxia-induced ventilatory neuroplasticity.
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Affiliation(s)
- Naomi L. Deacon
- Discipline of Physiology, School of Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
- Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Repatriation General Hospital, Daw Park, South Australia, Australia; and
| | - R. Doug McEvoy
- Discipline of Physiology, School of Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
- Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Repatriation General Hospital, Daw Park, South Australia, Australia; and
- School of Medicine, Flinders University, Bedford Park, South Australia, Australia
| | - Daniel L. Stadler
- Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Repatriation General Hospital, Daw Park, South Australia, Australia; and
| | - Peter G. Catcheside
- Discipline of Physiology, School of Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
- Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Repatriation General Hospital, Daw Park, South Australia, Australia; and
- School of Medicine, Flinders University, Bedford Park, South Australia, Australia
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11
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Tachikawa S, Nakayama K, Nakamura S, Mochizuki A, Iijima T, Inoue T. Coordinated Respiratory Motor Activity in Nerves Innervating the Upper Airway Muscles in Rats. PLoS One 2016; 11:e0166436. [PMID: 27832132 PMCID: PMC5104329 DOI: 10.1371/journal.pone.0166436] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 10/28/2016] [Indexed: 12/02/2022] Open
Abstract
Maintaining the patency of the upper airway during breathing is of vital importance. The activity of various muscles is related to the patency of the upper airway. In the present study, we examined the respiratory motor activity in the efferent nerves innervating the upper airway muscles to determine the movements of the upper airway during respiration under normocapnic conditions (pH = 7.4) and in hypercapnic acidosis (pH = 7.2). Experiments were performed on arterially perfused decerebrate rats aged between postnatal days 21–35. We recorded the efferent nerve activity in a branch of the cervical spinal nerve innervating the infrahyoid muscles (CN), the hypoglossal nerve (HGN), the external branch of the superior laryngeal nerve (SLN), and the recurrent laryngeal nerve (RLN) with the phrenic nerve (PN). Inspiratory nerve discharges were observed in all these nerves under normocapnic conditions. The onset of inspiratory discharges in the CN and HGN was slightly prior to those in the SLN and RLN. When the CO2 concentration in the perfusate was increased from 5% to 8% to prepare for hypercapnic acidosis, the peak amplitudes of the inspiratory discharges in all the recorded nerves were increased. Moreover, hypercapnic acidosis induced pre-inspiratory discharges in the CN, HGN, SLN, and RLN. The onset of pre-inspiratory discharges in the CN, HGN, and SLN was prior to that of discharges in the RLN. These results suggest that the securing of the airway that occurs a certain time before dilation of the glottis may facilitate ventilation and improve hypercapnic acidosis.
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Affiliation(s)
- Satoshi Tachikawa
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo 142–8555, Japan
- Department of Perioperative Medicine, Division of Anesthesiology, Showa University School of Dentistry, Oota-ku, Tokyo 145–8515, Japan
| | - Kiyomi Nakayama
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo 142–8555, Japan
- * E-mail:
| | - Shiro Nakamura
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo 142–8555, Japan
| | - Ayako Mochizuki
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo 142–8555, Japan
| | - Takehiko Iijima
- Department of Perioperative Medicine, Division of Anesthesiology, Showa University School of Dentistry, Oota-ku, Tokyo 145–8515, Japan
| | - Tomio Inoue
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo 142–8555, Japan
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