Journal of Applied Physiology, Vol 72, Issue 3 962-969, Copyright © 1992 by American Physiological Society

ARTICLES

Chemoreceptor and vagal influences on thyroarytenoid muscle activity in awake lambs during hypoxia

J. P. Praud, E. Canet and M. A. Bureau
Centre Jeremy Rill, Departement de Pediatrie, Faculte de Medecine, Universite de Sherbrooke, Quebec, Canada.

This study was designed to identify the various controllers of thyroarytenoid (TA) activity in lambs during resting breathing, hypocapnic hypoxia, and isocapnic hypoxia. The TA muscle is known as the major adductor of the laryngeal aperture. We assumed that both the chemoreceptors and vagal nerves would interact to inhibit TA activity during hypoxia and to favor the occurrence of hyperpnea as a defense against hypoxia. We recorded TA activity directly in 11 awake lambs, aged 11 to 22 days, and studied them in three groups: four normals, four carotid body denervated, and three vagotomized. To test the contribution of the chemoreceptors to TA activity, we used pure O2 tests (Dejours' test) to silence the effects of the peripheral arterial chemoreceptors on the larynx during resting breathing and during the course of two hypoxia tests (the first: hypocapnic hypoxia; the second: isocapnic hypoxia). Our results confirmed 1) that both the peripheral arterial chemoreceptors and the vagal nerves inhibit the TA activity of 15-day-old lambs, during both resting and hypocapnic hypoxia conditions, and 2) that their effects override the hypocapnic effects that would otherwise recruit the TA muscle and close the glottis during hypocapnic hypoxia. We also found that vagotomy, or the pure O2 test, causes major recruitment of TA activity. These findings confirm that 15-day-old lambs are capable of using sustained hyperventilation as a means of fighting hypoxia, and that, because of the control of both the vagus nerves and the chemoreceptors, the laryngeal dynamic is able to keep the glottis aperture actively open, thereby favoring the hyperpnea.

This article has been cited by other articles:

				K. D. O'Halloran and G. E. Bisgard Upper airway pressure-flow relationships and pharyngeal constrictor EMG activity during prolonged expiration in awake goats J Appl Physiol, July 1, 2008; 105(1): 100 - 108. [Abstract] [Full Text] [PDF]

				P.-H. Fortier, P. Reix, J. Arsenault, D. Dorion, and J.-P. Praud Active upper airway closure during induced central apneas in lambs is complete at the laryngeal level only J Appl Physiol, July 1, 2003; 95(1): 97 - 103. [Abstract] [Full Text] [PDF]

				J. Arsenault, F. Moreau-Bussiere, P. Reix, T. Niyonsenga, and J.-P. Praud Postnatal maturation of vagal respiratory reflexes in preterm and full-term lambs J Appl Physiol, May 1, 2003; 94(5): 1978 - 1986. [Abstract] [Full Text] [PDF]

				A. A. Hutchison, D. J. Burchfield, J. A. Wozniak, and S. J. Mohrman Laryngeal Muscle Activities with Cerebral Hypoxia-Ischemia in Newborn Lambs Am. J. Respir. Crit. Care Med., July 1, 2002; 166(1): 85 - 91. [Abstract] [Full Text] [PDF]

				V. Diaz, J. Arsenault, and J.-P. Praud Consequences of capsaicin treatment on pulmonary vagal reflexes and chemoreceptor activity in lambs J Appl Physiol, November 1, 2000; 89(5): 1709 - 1718. [Abstract] [Full Text] [PDF]

				T. C. Tai and S. L. Adamson Developmental changes in respiratory, febrile, and cardiovascular responses to PGE2 in newborn lambs Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2000; 278(6): R1460 - R1473. [Abstract] [Full Text] [PDF]

				V. Diaz, D. Dorion, I. Kianicka, P. Letourneau, and J.-P. Praud Vagal afferents and active upper airway closure during pulmonary edema in lambs J Appl Physiol, May 1, 1999; 86(5): 1561 - 1569. [Abstract] [Full Text] [PDF]

				S. RENOLLEAU, P. LETOURNEAU, T. NIYONSENGA, J.-P. PRAUD, and B. Gagne Thyroarytenoid Muscle Electrical Activity During Spontaneous Apneas in Preterm Lambs Am. J. Respir. Crit. Care Med., May 1, 1999; 159(5): 1396 - 1404. [Abstract] [Full Text] [PDF]

				I. Kianicka, V. Diaz, D. Dorion, and J.-P. Praud Coordination between glottic adductor muscle and diaphragm EMG activity in fetal lambs in utero J Appl Physiol, May 1, 1998; 84(5): 1560 - 1565. [Abstract] [Full Text] [PDF]

				I. Kianicka, V. Diaz, S. Renolleau, E. Canet, and J.-P. Praud Laryngeal and abdominal muscle electrical activity during periodic breathing in nonsedated lambs J Appl Physiol, February 1, 1998; 84(2): 669 - 675. [Abstract] [Full Text] [PDF]