title: Mechanisms of the deep, slow-wave, sleep-related increase of upper airway muscle tone in healthy humans.
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 CO2and 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 & NOTEWORTHYThe 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.
authors.affiliation: School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Amelia
authors.initials: A
authors.lastname: Hicks
authors.affiliation: School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Cori
authors.affiliation: School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Jordan
authors.affiliation: School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Christian L
authors.initials: CL
authors.lastname: Nicholas
authors.affiliation: Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Leszek
authors.initials: L
authors.lastname: Kubin
authors.affiliation: School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: John G
authors.initials: JG
authors.lastname: Semmler
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, University of California at San Diego, San Diego, California; and.
authors.forename: Atul
authors.initials: A
authors.lastname: Malhotra
authors.affiliation: School of Medicine and Medical Science, University College Dublin and Mater Misericordiae University Hospital, Dublin, Ireland.
authors.forename: David G P
authors.initials: DGP
authors.lastname: McSharry
authors.affiliation: School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia; johnat@unimelb.edu.au.
authors.forename: John A
authors.initials: JA
authors.lastname: Trinder
mesh_terms: D000328:Adult; D000403:Airway Resistance / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D004576:Electromyography / Q000379:methods; D006801:Humans; D008297:Male; D009129:Muscle Tonus / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D017286:Polysomnography / Q000379:methods; D011312:Pressure; D012018:Reflex / Q000502:physiology; D012119:Respiration; D012137:Respiratory System / Q000378:metabolism / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide
keywords: genioglossus; non-rapid eye movement sleep; slow-wave sleep; tensor palatini; upper airway muscles