Emerging principles and neural substrates underlying tonic sleep-state-dependent influences on respiratory motor activity.

Full Abstract

Respiratory muscles with dual respiratory and non-respiratory functions (e.g. the pharyngeal and intercostal muscles) show greater suppression of activity in sleep than the diaphragm, a muscle almost entirely devoted to respiratory function. This sleep-related suppression of activity is most apparent in the tonic component of motor activity, which has functional implications of a more collapsible upper airspace in the case of pharyngeal muscles, and decreased functional residual capacity in the case of intercostal muscles. A major source of tonic drive to respiratory motoneurons originates from neurons intimately involved in states of brain arousal, i.e. neurons not classically involved in generating respiratory rhythm and pattern per se. The tonic drive to hypoglossal motoneurons, a respiratory motor pool with both respiratory and non-respiratory functions, is mediated principally by noradrenergic and glutamatergic inputs, these constituting the essential components of the wakefulness stimulus. These tonic excitatory drives are opposed by tonic inhibitory glycinergic and gamma-amino butyric acid (GABA) inputs that constrain the level of respiratory-related motor activity, with the balance determining net motor tone. In sleep, the excitatory inputs are withdrawn and GABA release into the brainstem is increased, thus decreasing respiratory motor tone and predisposing susceptible individuals to hypoventilation and obstructive sleep apnoea.

Author information

Author/s: Horner, Richard L (RL);

Affiliation: Department of Medicine, University of Toronto, , Room 7308 Medical Sciences Building, 1 Kings College Circle, Toronto, Ontario M5S 1A8, Canada. richard.horner(-atsign-)utoronto.ca

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't; Review

Journal: Philosophical transactions of the Royal Society of London. Series B, Biological sciences (Philos Trans R Soc Lond B Biol Sci), published in England. (Language: eng)

Reference: 2009-Sep; vol 364 (issue 1529) : pp 2553-64

Dates: Created 2009/08/04; Completed 2009/10/30;

PMID: 19651656, status: MEDLINE (last retrieval date: 10/30/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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