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Dawson A, Avraam J, Nicholas CL, Kay A, Thornton T, Feast N, Fridgant MD, O’Donoghue FJ, Trinder J, Jordan AS. Mechanisms underlying the prolonged activation of the genioglossus following arousal from sleep. Sleep 2024; 47:zsad202. [PMID: 37503934 PMCID: PMC10782491 DOI: 10.1093/sleep/zsad202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/17/2023] [Indexed: 07/29/2023] Open
Abstract
STUDY OBJECTIVES Transient arousal from sleep has been shown to elicit a prolonged increase in genioglossus muscle activity that persists following the return to sleep and which may protect against subsequent airway collapse. We hypothesized that this increased genioglossal activity following return to sleep after an arousal is due to persistent firing of inspiratory-modulated motor units (MUs) that are recruited during the arousal. METHODS Thirty-four healthy participants were studied overnight while wearing a nasal mask with pneumotachograph to measure ventilation and with 4 intramuscular genioglossus EMG electrodes. During stable N2 and N3 sleep, auditory tones were played to induce brief (3-15s) AASM arousals. Ventilation and genioglossus MUs were quantified before the tone, during the arousal and for 10 breaths after the return to sleep. RESULTS A total of 1089 auditory tones were played and gave rise to 239 MUs recorded across arousal and the return to sleep in 20 participants (aged 23 ± 4.2 years and BMI 22.5 ± 2.2 kg/m2). Ventilation was elevated above baseline during arousal and the first post-arousal breath (p < .001). Genioglossal activity was elevated for five breaths following the return to sleep, due to increased firing rate and recruitment of inspiratory modulated MUs, as well as a small increase in tonic MU firing frequency. CONCLUSIONS The sustained increase in genioglossal activity that occurs on return to sleep after arousal is primarily a result of persistent activity of inspiratory-modulated MUs, with a slight contribution from tonic units. Harnessing genioglossal activation following arousal may potentially be useful for preventing obstructive respiratory events.
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Affiliation(s)
- Andrew Dawson
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Joanne Avraam
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
- Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia
| | - Christian L Nicholas
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
- Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia
| | - Amanda Kay
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Therese Thornton
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Nicole Feast
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Monika D Fridgant
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Fergal J O’Donoghue
- Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia
- Faculty of Medicine, The University of Melbourne, Parkville, Victoria, Australia
| | - John Trinder
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Amy S Jordan
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, Australia
- Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia
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Avraam J, Dawson A, Nicholas CL, Fridgant MD, Fan FL, Kay A, Koay ZY, Greig R, O'Donoghue FJ, Trinder J, Jordan AS. The influence of alcohol on genioglossus single motor units in men and women during wakefulness. Exp Physiol 2023; 108:491-502. [PMID: 36533973 PMCID: PMC10103883 DOI: 10.1113/ep090580] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022]
Abstract
NEW FINDINGS What is the central question of this study? How does alcohol intake, which worsens obstructive sleep apnoea, alter motor control of the genioglossus muscle, an upper airway dilator, in healthy awake human volunteers, and does alcohol alter genioglossus muscle afterdischarge? What is the main finding and its importance? Alcohol consumption had a very minor effect on the activity of the genioglossus in healthy young individuals studied during wakefulness and did not alter afterdischarge, leaving open the possibility that alcohol worsens obstructive sleep apnoea via other mechanisms. ABSTRACT Alcohol worsens obstructive sleep apnoea (OSA). This effect is thought to be due to alcohol's depressant effect on upper airway dilator muscles such as the genioglossus, but how alcohol reduces genioglossal activity is unknown. The aim of this study was to investigate the effect of alcohol consumption on genioglossus muscle single motor units (MUs). Sixteen healthy individuals were studied on two occasions (alcohol: breath alcohol concentration ∼0.07% and placebo). They were instrumented with a nasal mask, four intramuscular genioglossal EMG electrodes, and an ear oximeter. They were exposed to 8-12 hypoxia trials (45-60 s of 10% O2 followed by one breath of 100% O2 ) while awake. MUs were sorted according to their firing patterns and quantified during baseline, hypoxia and recovery. For the alcohol and placebo conditions, global muscle activity (mean ± SD peak inspiratory EMG = 119.3 ± 44.1 and 126.5 ± 51.9 μV, respectively, P = 0.53) and total number of MUs recorded at baseline (68 and 67, respectively) were similar. Likewise, the peak discharge frequency did not differ between conditions (21.2 ± 4.28 vs. 22.4 ± 4.08 Hz, P = 0.09). There was no difference between conditions in the number (101 vs. 88, respectively) and distribution of MU classes during hypoxia, and afterdischarge duration was also similar. In this study, alcohol had a very minor effect on genioglossal activity and afterdischarge in these otherwise healthy young individuals studied while awake. If similar effects are observed during sleep, it would suggest that the worsening of OSA following alcohol may be related to increased upper airway resistance/nasal congestion or arousal threshold changes.
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Affiliation(s)
- Joanne Avraam
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
- Department of Respiratory and Sleep Medicine and Institute for Breathing and SleepAustin HealthHeidelbergVictoriaAustralia
| | - Andrew Dawson
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
| | - Christian L. Nicholas
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
- Department of Respiratory and Sleep Medicine and Institute for Breathing and SleepAustin HealthHeidelbergVictoriaAustralia
| | - Monika D. Fridgant
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
| | - Feiven Lee Fan
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
| | - Amanda Kay
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
| | - Zi Yi Koay
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
| | - Rachel Greig
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
| | - Fergal J. O'Donoghue
- Department of Respiratory and Sleep Medicine and Institute for Breathing and SleepAustin HealthHeidelbergVictoriaAustralia
- Faculty of MedicineUniversity of MelbourneParkvilleVictoriaAustralia
| | - John Trinder
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
| | - Amy S. Jordan
- Melbourne School of Psychological SciencesUniversity of MelbourneMelbourneAustralia
- Department of Respiratory and Sleep Medicine and Institute for Breathing and SleepAustin HealthHeidelbergVictoriaAustralia
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Avraam J, Dawson A, Feast N, Fan FL, D Frigant M, Kay A, Koay ZY, Jia P, Greig R, Thornton T, Nicholas CL, O'Donoghue FJ, Trinder J, Jordan AS. After-Discharge in the Upper Airway Muscle Genioglossus Following Brief Hypoxia. Sleep 2021; 44:6208283. [PMID: 33822200 DOI: 10.1093/sleep/zsab084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/10/2021] [Indexed: 11/13/2022] Open
Abstract
STUDY OBJECTIVES Genioglossus after-discharge is thought to protect against pharyngeal collapse by minimising periods of low upper airway muscle activity. How genioglossus after-discharge occurs and which single motor units (SMUs) are responsible for the phenomenon are unknown. The aim of this study was to investigate genioglossal after-discharge. METHODS During wakefulness, after-discharge was elicited 8-12 times in healthy individuals with brief isocapnic hypoxia (45-60s of 10%O2 in N2) terminated by a single breath of 100% O2. Genioglossus SMUs were designated as firing solely, or at increased rate, during inspiration (Inspiratory phasic [IP] and inspiratory tonic [IT] respectively); solely, or at increased rate, during expiration (Expiratory phasic [EP] or expiratory tonic [ET] respectively) or firing constantly without respiratory modulation (Tonic). SMUs were quantified at baseline, the end of hypoxia, the hyperoxic breath and the following 8 normoxic breaths. RESULTS 210 SMU's were identified in 17 participants. Genioglossus muscle activity was elevated above baseline for 7 breaths after hyperoxia (p<0.001), indicating a strong after-discharge effect. After-discharge occurred due to persistent firing of IP and IT units that were recruited during hypoxia, with minimal changes in ET, EP or Tonic SMUs. The firing frequency of units that were already active changed minimally during hypoxia or the afterdischarge period (P>0.05). CONCLUSION That genioglossal after-discharge is almost entirely due to persistent firing of previously silent inspiratory SMUs provides insight into the mechanisms responsible for the phenomenon and supports the hypothesis that the inspiratory and expiratory/tonic motor units within the muscle have idiosyncratic functions.
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Affiliation(s)
- Joanne Avraam
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia.,Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia
| | - Andrew Dawson
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Nicole Feast
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Feiven Lee Fan
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Monika D Frigant
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Amanda Kay
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Zi Yi Koay
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Pingdong Jia
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Rachel Greig
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Therese Thornton
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Christian L Nicholas
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia.,Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia
| | - Fergal J O'Donoghue
- Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia.,Faculty of Medicine, University of Melbourne, Parkville, Victoria, Australia
| | - John Trinder
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Amy S Jordan
- Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia.,Department of Respiratory and Sleep Medicine and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia
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Luu BL, Saboisky JP, McBain RA, Trinder JA, White DP, Taylor JL, Gandevia SC, Butler JE. Genioglossus motor unit activity in supine and upright postures in obstructive sleep apnea. Sleep 2020; 43:5686881. [PMID: 31875918 DOI: 10.1093/sleep/zsz316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/03/2019] [Indexed: 11/14/2022] Open
Abstract
This study investigated whether a change in posture affected the activity of the upper-airway dilator muscle genioglossus in participants with and without obstructive sleep apnea (OSA). During wakefulness, a monopolar needle electrode was used to record single motor unit activity in genioglossus in supine and upright positions to alter the gravitational load that causes narrowing of the upper airway. Activity from 472 motor units was recorded during quiet breathing in 17 males, nine of whom had OSA. The mean number of motor units for each participant was 11.8 (SD 3.4) in the upright and 16.0 (SD 4.2) in the supine posture. For respiratory-modulated motor units, there were no significant differences in discharge frequencies between healthy controls and participants with OSA. Within each breath, genioglossus activity increased through the recruitment of phasic motor units and an increase in firing rate, with an overall increase of ~6 Hz (50%) across both postures and participant groups. However, the supine posture did not lead to compensatory increases in the peak discharge frequencies of inspiratory and expiratory motor units, despite the increase in gravitational load on the upper airway. Posture also had no significant effect on the discharge frequency of motor units that showed no respiratory modulation during quiet breathing. We postulate that, in wakefulness, any increase in genioglossus activity to compensate for the gravitational effects on the upper airway is achieved primarily through the recruitment of additional motor units in both healthy controls and participants with OSA.
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Affiliation(s)
- Billy L Luu
- Neuroscience Research Australia, Randwick, NSW, Australia
| | - Julian P Saboisky
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Rachel A McBain
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | | | - David P White
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Janet L Taylor
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia.,Edith Cowan University, Joondalup, WA, Australia
| | - Simon C Gandevia
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Jane E Butler
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
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5
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Manlises CO, Chen J, Huang C. Dynamic tongue area measurements in ultrasound images for adults with obstructive sleep apnea. J Sleep Res 2020; 29:e13032. [DOI: 10.1111/jsr.13032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 02/09/2020] [Accepted: 02/25/2020] [Indexed: 12/15/2022]
Affiliation(s)
- Cyrel Ontimare Manlises
- Department of Biomedical Engineering National Cheng Kung University Tainan Taiwan
- School of Electrical, Electronics, and Computer Engineering Mapúa University Manila Philippines
| | - Jeng‐Wen Chen
- Department of Otolaryngology–Head and Neck Surgery Cardinal Tien Hospital New Taipei City Taiwan
- School of Medicine Fu Jen Catholic University New Taipei City Taiwan
- Department of Otolaryngology–Head and Neck Surgery National Taiwan University Hospital Taipei Taiwan
- Department of Nursing Cardinal Tien Junior College of Healthcare and Management New Taipei City Taiwan
| | - Chih‐Chung Huang
- Department of Biomedical Engineering National Cheng Kung University Tainan Taiwan
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Martins RT, Carberry JC, Wang D, Rowsell L, Grunstein RR, Eckert DJ. Morphine alters respiratory control but not other key obstructive sleep apnoea phenotypes: a randomised trial. Eur Respir J 2020; 55:13993003.01344-2019. [DOI: 10.1183/13993003.01344-2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 02/25/2020] [Indexed: 11/05/2022]
Abstract
Accidental opioid-related deaths are increasing. These often occur during sleep. Opioids such as morphine may worsen obstructive sleep apnoea (OSA). Thus, people with OSA may be at greater risk of harm from morphine. Possible mechanisms include respiratory depression and reductions in drive to the pharyngeal muscles to increase upper airway collapsibility. However, the effects of morphine on the four key phenotypic causes of OSA (upper airway collapsibility (pharyngeal critical closure pressure; Pcrit), pharyngeal muscle responsiveness, respiratory arousal threshold and ventilatory control (loop gain) during sleep) are unknown.21 males with OSA (apnoea–hypopnoea index range 7–67 events·h−1) were studied on two nights (1-week washout) according to a double-blind, randomised, cross-over design (ACTRN12613000858796). Participants received 40 mg of MS-Contin on one visit and placebo on the other. Brief reductions in continuous positive airway pressure (CPAP) from the therapeutic level were delivered to induce airflow limitation during non-rapid eye movement (REM) sleep to quantify the four phenotypic traits. Carbon dioxide was delivered via nasal mask on therapeutic CPAP to quantify hypercapnic ventilatory responses during non-REM sleep.Compared to placebo, 40 mg of morphine did not change Pcrit (−0.1±2.4 versus −0.4±2.2 cmH2O, p=0.58), genioglossus muscle responsiveness (−2.2 (−0.87 to −5.4) versus −1.2 (−0.3 to −3.5) μV·cmH2O−1, p=0.22) or arousal threshold (−16.7±6.8 versus −15.4±6.0 cmH2O, p=0.41), but did reduce loop gain (−10.1±2.6 versus −4.4±2.1, p=0.04) and hypercapnic ventilatory responses (7.3±1.2 versus 6.1±1.5 L·min−1, p=0.006).Concordant with recent clinical findings, 40 mg of MS-Contin does not systematically impair airway collapsibility, pharyngeal muscle responsiveness or the arousal threshold in moderately severe OSA patients. However, consistent with blunted chemosensitivity, ventilatory control is altered.
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Measurement and State-Dependent Modulation of Hypoglossal Motor Excitability and Responsivity In-Vivo. Sci Rep 2020; 10:550. [PMID: 31953471 PMCID: PMC6969049 DOI: 10.1038/s41598-019-57328-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 12/19/2019] [Indexed: 12/17/2022] Open
Abstract
Motoneurons are the final output pathway for the brain’s influence on behavior. Here we identify properties of hypoglossal motor output to the tongue musculature. Tongue motor control is critical to the pathogenesis of obstructive sleep apnea, a common and serious sleep-related breathing disorder. Studies were performed on mice expressing a light sensitive cation channel exclusively on cholinergic neurons (ChAT-ChR2(H134R)-EYFP). Discrete photostimulations under isoflurane-induced anesthesia from an optical probe positioned above the medullary surface and hypoglossal motor nucleus elicited discrete increases in tongue motor output, with the magnitude of responses dependent on stimulation power (P < 0.001, n = 7) and frequency (P = 0.002, n = 8, with responses to 10 Hz stimulation greater than for 15–25 Hz, P < 0.022). Stimulations during REM sleep elicited significantly reduced responses at powers 3–20 mW compared to non-rapid eye movement (non-REM) sleep and wakefulness (each P < 0.05, n = 7). Response thresholds were also greater in REM sleep (10 mW) compared to non-REM and waking (3 to 5 mW, P < 0.05), and the slopes of the regressions between input photostimulation powers and output motor responses were specifically reduced in REM sleep (P < 0.001). This study identifies that variations in photostimulation input produce tunable changes in hypoglossal motor output in-vivo and identifies REM sleep specific suppression of net motor excitability and responsivity.
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Pilarski JQ, Leiter JC, Fregosi RF. Muscles of Breathing: Development, Function, and Patterns of Activation. Compr Physiol 2019; 9:1025-1080. [PMID: 31187893 DOI: 10.1002/cphy.c180008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This review is a comprehensive description of all muscles that assist lung inflation or deflation in any way. The developmental origin, anatomical orientation, mechanical action, innervation, and pattern of activation are described for each respiratory muscle fulfilling this broad definition. In addition, the circumstances in which each muscle is called upon to assist ventilation are discussed. The number of "respiratory" muscles is large, and the coordination of respiratory muscles with "nonrespiratory" muscles and in nonrespiratory activities is complex-commensurate with the diversity of activities that humans pursue, including sleep (8.27). The capacity for speech and adoption of the bipedal posture in human evolution has resulted in patterns of respiratory muscle activation that differ significantly from most other animals. A disproportionate number of respiratory muscles affect the nose, mouth, pharynx, and larynx, reflecting the vital importance of coordinated muscle activity to control upper airway patency during both wakefulness and sleep. The upright posture has freed the hands from locomotor functions, but the evolutionary history and ontogeny of forelimb muscles pervades the patterns of activation and the forces generated by these muscles during breathing. The distinction between respiratory and nonrespiratory muscles is artificial, as many "nonrespiratory" muscles can augment breathing under conditions of high ventilator demand. Understanding the ontogeny, innervation, activation patterns, and functions of respiratory muscles is clinically useful, particularly in sleep medicine. Detailed explorations of how the nervous system controls the multiple muscles required for successful completion of respiratory behaviors will continue to be a fruitful area of investigation. © 2019 American Physiological Society. Compr Physiol 9:1025-1080, 2019.
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Affiliation(s)
- Jason Q Pilarski
- Department of Biological and Dental Sciences, Idaho State University Pocatello, Idaho, USA
| | - James C Leiter
- Department of Molecular and Systems Biology, The Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA
| | - Ralph F Fregosi
- Departments of Physiology and Neuroscience, The University of Arizona, Tucson, Arizona, USA
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Hicks A, Cori JM, Jordan AS, Nicholas CL, Kubin L, Semmler JG, Malhotra A, McSharry DGP, Trinder JA. Mechanisms of the deep, slow-wave, sleep-related increase of upper airway muscle tone in healthy humans. J Appl Physiol (1985) 2017; 122:1304-1312. [PMID: 28255086 DOI: 10.1152/japplphysiol.00872.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 02/14/2017] [Accepted: 02/23/2017] [Indexed: 12/21/2022] Open
Abstract
Upper airway muscle activity is reportedly elevated during slow-wave sleep (SWS) when compared with lighter sleep stages. To uncover the possible mechanisms underlying this elevation, we explored the correlation between different indices of central and reflex inspiratory drive, such as the changes in airway pressure and end-expiratory CO2 and the changes in the genioglossus (GG) and tensor palatini (TP) muscle activity accompanying transitions from the lighter N2 to the deeper N3 stage of non-rapid eye movement (NREM) sleep in healthy young adult men. Forty-six GG and 38 TP continuous electromyographic recordings were obtained from 16 men [age: 20 ± 2.5 (SD) yr; body mass index: 22.5 ± 1.8 kg/m2] during 32 transitions from NREM stages N2 to N3. GG but not TP activity increased following transition into N3 sleep, and the increase was positively correlated with more negative airway pressure, increased end-tidal CO2, increased peak inspiratory flow, and increased minute ventilation. None of these correlations was statistically significant for TP. Complementary GG and TP single motor unit analysis revealed a mild recruitment of GG units and derecruitment of TP units during the N2 to N3 transitions. These findings suggest that, in healthy individuals, the increased GG activity during SWS is driven primarily by reflex stimulation of airway mechanoreceptors and central chemoreceptors.NEW & NOTEWORTHY The characteristic increase in the activity of the upper airway dilator muscle genioglossus during slow-wave sleep (SWS) in young healthy individuals was found to be related to increased stimulation of airway mechanoreceptors and central chemoreceptors. No evidence was found for the presence of a central SWS-specific drive stimulating genioglossus activity in young healthy individuals. However, it remains to be determined whether a central drive exists in obstructive sleep apnea patients.
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Affiliation(s)
- Amelia Hicks
- School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Jennifer M Cori
- School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Amy S Jordan
- School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Christian L Nicholas
- School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Leszek Kubin
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - John G Semmler
- School of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California at San Diego, San Diego, California; and
| | - David G P McSharry
- School of Medicine and Medical Science, University College Dublin and Mater Misericordiae University Hospital, Dublin, Ireland
| | - John A Trinder
- School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia;
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10
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Impact of arousal threshold and respiratory effort on the duration of breathing events across sleep stage and time of night. Respir Physiol Neurobiol 2016; 237:35-41. [PMID: 28040523 DOI: 10.1016/j.resp.2016.12.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/23/2016] [Accepted: 12/16/2016] [Indexed: 11/21/2022]
Abstract
PURPOSE The frequency and duration of breathing events are influenced by sleep stage and time of day. In the present study we examined if these modifications are linked to adaptations in the arousal threshold and/or the magnitude of respiratory effort during and immediately after breathing events. METHODS Participants with sleep apnea slept for 3h in the evening and morning. For breathing events detected during these sessions the rate of change of respiratory effort, maximum respiratory effort immediately prior to termination of an event, and the maximum tidal volume and the minimum partial pressure of end-tidal carbon dioxide (PETCO2) immediately following an event were measured. RESULTS The rate of change of respiratory effort was similar in N2 compared to N1 but the maximum respiratory effort immediately prior to event termination was greater (-10.7±1.2 vs. -9.6±1.0cmH2O/s, P<0.05). Likewise, tidal volume was increased (1169±105 vs. 1082±100ml, P<0.05) and PETCO2 was decreased (37.0±0.8 vs. 37.7±0.8mmHg P<0.05) following events in N2 compared to N1. A similar tidal volume and PETCO2 response was evident following events in the morning compared to the evening independent of sleep stage. CONCLUSIONS We conclude that alterations in the arousal threshold, reflected by an increase in respiratory effort at event termination, coupled to increases in tidal volume and reductions in PETCO2 contribute to modifications in event duration and frequency associated with variations in sleep state or time of night.
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11
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Kubin L. Neural Control of the Upper Airway: Respiratory and State-Dependent Mechanisms. Compr Physiol 2016; 6:1801-1850. [PMID: 27783860 DOI: 10.1002/cphy.c160002] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Upper airway muscles subserve many essential for survival orofacial behaviors, including their important role as accessory respiratory muscles. In the face of certain predisposition of craniofacial anatomy, both tonic and phasic inspiratory activation of upper airway muscles is necessary to protect the upper airway against collapse. This protective action is adequate during wakefulness, but fails during sleep which results in recurrent episodes of hypopneas and apneas, a condition known as the obstructive sleep apnea syndrome (OSA). Although OSA is almost exclusively a human disorder, animal models help unveil the basic principles governing the impact of sleep on breathing and upper airway muscle activity. This article discusses the neuroanatomy, neurochemistry, and neurophysiology of the different neuronal systems whose activity changes with sleep-wake states, such as the noradrenergic, serotonergic, cholinergic, orexinergic, histaminergic, GABAergic and glycinergic, and their impact on central respiratory neurons and upper airway motoneurons. Observations of the interactions between sleep-wake states and upper airway muscles in healthy humans and OSA patients are related to findings from animal models with normal upper airway, and various animal models of OSA, including the chronic-intermittent hypoxia model. Using a framework of upper airway motoneurons being under concurrent influence of central respiratory, reflex and state-dependent inputs, different neurotransmitters, and neuropeptides are considered as either causing a sleep-dependent withdrawal of excitation from motoneurons or mediating an active, sleep-related inhibition of motoneurons. Information about the neurochemistry of state-dependent control of upper airway muscles accumulated to date reveals fundamental principles and may help understand and treat OSA. © 2016 American Physiological Society. Compr Physiol 6:1801-1850, 2016.
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Affiliation(s)
- Leszek Kubin
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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12
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Horner RL. Neural control of the upper airway: integrative physiological mechanisms and relevance for sleep disordered breathing. Compr Physiol 2013; 2:479-535. [PMID: 23728986 DOI: 10.1002/cphy.c110023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The various neural mechanisms affecting the control of the upper airway muscles are discussed in this review, with particular emphasis on structure-function relationships and integrative physiological motor-control processes. Particular foci of attention include the respiratory function of the upper airway muscles, and the various reflex mechanisms underlying their control, specifically the reflex responses to changes in airway pressure, reflexes from pulmonary receptors, chemoreceptor and baroreceptor reflexes, and postural effects on upper airway motor control. This article also addresses the determinants of upper airway collapsibility and the influence of neural drive to the upper airway muscles, and the influence of common drugs such as ethanol, sedative hypnotics, and opioids on upper airway motor control. In addition to an examination of these basic physiological mechanisms, consideration is given throughout this review as to how these mechanisms relate to integrative function in the intact normal upper airway in wakefulness and sleep, and how they may be involved in the pathogenesis of clinical problems such obstructive sleep apnea hypopnea.
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