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This Article Full Text Full Text (PDF) All Versions of this Article: 92/1/27    most recent expphysiol.2006.033720v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mahamed, S. Articles by Mitchell, G. S. Search for Related Content PubMed PubMed Citation Articles by Mahamed, S. Articles by Mitchell, G. S. Related Collections Themed Issue papers

¹ Department of Comparative Biosciences, University of Wisconsin Madison, 2015 Linden Drive, Madison, WI 53706, USA

Although neuroplasticity is an important property of the respiratory motor control system, its existence has been appreciated only in recent years and, as a result, its functional significance is not completely understood. The most frequently studied models of respiratory plasticity is respiratory long-term facilitation (LTF) following acute intermittent hypoxia and enhanced LTF following chronic intermittent hypoxia. Since intermittent hypoxia is a prominent feature of sleep-disordered breathing, LTF and/or enhanced LTF may compensate for factors that predispose to sleep-disordered breathing, particularly during obstructive sleep apnoea (OSA). Long-term facilitation has been studied most frequently in rats, and exhibits interesting properties consistent with a role in stabilizing breathing during sleep. Specifically, LTF: (1) is prominent in upper airway respiratory motor activity, suggesting that it stabilizes upper airways and maintains airway patency; (2) is most prominent during sleep in unanaesthetized rats; and (3) exhibits sexual dimorphism (greatest in young male and middle-aged female rats; smallest in middle-aged male and young female rats). Although these features are consistent with the hypothesis that upper airway LTF minimizes the prevalence of OSA in humans, there is little direct evidence for such an effect. Here we review advances in our understanding of LTF and its underlying mechanisms and present evidence concerning a potential role for LTF in maintaining upper airway patency, stabilizing breathing and preventing OSA in humans. Regardless of the relationship between LTF and OSA, a detailed understanding of cellular and synaptic mechanisms that underlie LTF may guide the development of new drugs to regulate upper airway tone, thereby offsetting the tendency for upper airway collapse characteristic of heavy snoring and OSA.

(Received 9 October 2006; accepted after revision 6 November 2006; first published online 10 November 2006)
Corresponding author G. S. Mitchell: Department of Comparative Biosciences, University of Wisconsin Madison, 2015 Linden Drive, Madison, WI 53706, USA. Email: mitchell{at}svm.vetmed.wisc.edu

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