HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 98/5/1761    most recent 01142.2004v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science 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 Web of Science (16) Citing Articles via Google Scholar Google Scholar Articles by Fuller, D. D. Search for Related Content PubMed PubMed Citation Articles by Fuller, D. D.

Episodic hypoxia induces long-term facilitation of neural drive to tongue protrudor and retractor muscles

Department of Physical Therapy, University of Florida, Gainesville, Florida

Submitted 11 October 2004 ; accepted in final form 4 January 2005

Hypoxic episodes can evoke a prolonged augmentation of inspiratory motor output called long-term facilitation (LTF). Hypoglossal (XII) LTF has been assumed to represent increased tongue protrudor muscle activation and pharyngeal airway dilation. However, recent studies indicate that tongue protrudor and retractor muscles are coactivated during inspiration, a behavior that promotes upper airway patency by reducing airway compliance. These experiments tested the hypothesis that XII LTF is manifest as increased inspiratory drive to both tongue protrudor and retractor muscles. Neurograms were recorded in the medial XII nerve branch (XIIMED; contains tongue protrudor motor axons), the lateral XII nerve branch (XIILAT; contains tongue retractor motor axons), and the phrenic nerve in anesthetized, vagotomized, paralyzed, ventilated male rats. Strict isocapnia was maintained for 60 min after five 3-min hypoxic episodes (arterial PO₂ = 35 ± 2 Torr) or sham treatment. Peak inspiratory burst amplitude showed a persistent increase in XIIMED, XIILAT, and phrenic nerves during the hour after episodic hypoxia (P < 0.05 vs. sham). This effect was present regardless of the quantification method (e.g., % baseline vs. percent maximum); however, comparisons of the relative magnitude of LTF between neurograms (e.g., XIIMED vs. XIILAT) varied with the normalization procedure. There was no persistent effect of episodic hypoxia on inspiratory burst frequency (P > 0.05 vs. sham). These data demonstrate that episodic hypoxia induces LTF of inspiratory drive to both tongue protrudor and retractor muscles and underscore the potential contribution of tongue muscle coactivation to regulation of upper airway patency.

respiratory control; respiratory neurons; plasticity

This article has been cited by other articles:

				K.-Z. Lee, P. J. Reier, and D. D. Fuller Phrenic Motoneuron Discharge Patterns During Hypoxia-Induced Short-Term Potentiation in Rats J Neurophysiol, October 1, 2009; 102(4): 2184 - 2193. [Abstract] [Full Text] [PDF]

				S. Ryan and P. Nolan Long-term facilitation of upper airway muscle activity induced by episodic upper airway negative pressure and hypoxia in spontaneously breathing anaesthetized rats J. Physiol., July 1, 2009; 587(13): 3343 - 3353. [Abstract] [Full Text] [PDF]

				S. Ryan and P. Nolan Episodic hypoxia induces long-term facilitation of upper airway muscle activity in spontaneously breathing anaesthetized rats J. Physiol., July 1, 2009; 587(13): 3329 - 3342. [Abstract] [Full Text] [PDF]

				L. R. DeRuisseau, D. D. Fuller, K. Qiu, K. C. DeRuisseau, W. H. Donnelly Jr, C. Mah, P. J. Reier, and B. J. Byrne Neural deficits contribute to respiratory insufficiency in Pompe disease PNAS, June 9, 2009; 106(23): 9419 - 9424. [Abstract] [Full Text] [PDF]

				J. H. Mateika and G. Narwani Intermittent hypoxia and respiratory plasticity in humans and other animals: does exposure to intermittent hypoxia promote or mitigate sleep apnoea? Exp Physiol, March 1, 2009; 94(3): 279 - 296. [Abstract] [Full Text] [PDF]

				H. Wadhwa, C. Gradinaru, G. J. Gates, M. S. Badr, and J. H. Mateika Impact of intermittent hypoxia on long-term facilitation of minute ventilation and heart rate variability in men and women: do sex differences exist? J Appl Physiol, June 1, 2008; 104(6): 1625 - 1633. [Abstract] [Full Text] [PDF]

				J. Terada, A. Nakamura, W. Zhang, M. Yanagisawa, T. Kuriyama, Y. Fukuda, and T. Kuwaki Ventilatory long-term facilitation in mice can be observed during both sleep and wake periods and depends on orexin J Appl Physiol, February 1, 2008; 104(2): 499 - 507. [Abstract] [Full Text] [PDF]

				A. Tadjalli, J. Duffin, Y. M. Li, H. Hong, and J. Peever Inspiratory activation is not required for episodic hypoxia-induced respiratory long-term facilitation in postnatal rats J. Physiol., December 1, 2007; 585(2): 593 - 606. [Abstract] [Full Text] [PDF]

				K.-Z. Lee, D. D. Fuller, I-J. Lu, J.-T. Lin, and J.-C. Hwang Neural drive to tongue protrudor and retractor muscles following pulmonary C-fiber activation J Appl Physiol, January 1, 2007; 102(1): 434 - 444. [Abstract] [Full Text] [PDF]

				S. Mahamed and G. S. Mitchell Sleep Apnoea & Hypertension: Physiological bases for a causal relation: Is there a link between intermittent hypoxia-induced respiratory plasticity and obstructive sleep apnoea? Exp Physiol, January 1, 2007; 92(1): 27 - 37. [Abstract] [Full Text] [PDF]

				D. P. Harris, A. Balasubramaniam, M. S. Badr, and J. H. Mateika Long-term facilitation of ventilation and genioglossus muscle activity is evident in the presence of elevated levels of carbon dioxide in awake humans Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2006; 291(4): R1111 - R1119. [Abstract] [Full Text] [PDF]

				E. S. Katz, C. L. Marcus, and D. P. White Influence of Airway Pressure on Genioglossus Activity during Sleep in Normal Children Am. J. Respir. Crit. Care Med., April 15, 2006; 173(8): 902 - 909. [Abstract] [Full Text] [PDF]