Format

Send to

Choose Destination
Am J Respir Crit Care Med. 2005 Jun 15;171(12):1403-7. Epub 2005 Mar 18.

PO2-dependent changes in intrinsic and extrinsic tongue muscle activities in the rat.

Author information

1
Department of Physiology, College of Medicine, University of Arizona, Tucson, AZ 85721-0093, USA. ebailey@u.arizona.edu

Abstract

RATIONALE:

Historically, respiratory-related research in sleep apnea has focused exclusively on the extrinsic tongue muscles (i.e., genioglossus, hyoglossus, and styloglossus). Until recently, the respiratory control and function of intrinsic tongue muscles (i.e., inferior and superior longitudinalis, transverses, and verticalis), which comprise the bulk of the tongue, were unknown.

OBJECTIVES:

The current study sought to determine if extrinsic and intrinsic tongue muscles are coactivated in conditions of hypoxemia comparable to that experienced by adults with obstructive sleep apnea.

MEASUREMENTS:

Esophageal pressure and EMG activity of an extrinsic (hyoglossus) and an intrinsic (superior longitudinal) tongue muscle were studied in anesthetized, tracheotomized, spontaneously breathing rats. Average EMG activity was compared in a control gas condition (Pa(O2), 160 +/- 12 mm Hg) and in mild isocapnic hypoxia (Pa(O2), 69 +/- 7.2 mm Hg), with and without brief (3-breath) airway occlusions, pre- and postbilateral vagotomy.

MAIN RESULTS:

(1) intrinsic and extrinsic tongue muscles are coactivated in mild hypoxia, (2) airway occlusion increased the activities of intrinsic retractor muscles in mild hypoxia, and (3) extrinsic retractor muscles have a steeper rate of rise of activity and an earlier burst onset relative to intrinsic retractor activities in mild hypoxia.

CONCLUSIONS:

These findings support our working hypothesis that airway patency is maintained not simply by activation of extrinsic tongue muscles but by the coactivation of intrinsic and extrinsic protrudor and retractor muscles.

PMID:
15778485
PMCID:
PMC2718482
DOI:
10.1164/rccm.200411-1550OC
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center