Changes in laryngeal muscle activities during hypercapnia in the cat

The larynx has three functions: phonation, airway protection, and respiration. Few studies have dealt with laryngeal respiratory function. To elucidate respiratory regulation by the larynx, we studied the changes in the activity of the intrinsic laryngeal muscles during hypercapnia in decerebrated c...

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Bibliographic Details
Published in:Otolaryngology-head and neck surgery 1998-04, Vol.118 (4), p.537-544
Main Authors: ADACHI, TOMOYUKI, UMEZAKI, TOSHIRO, MATSUSE, TOSHIAKI, SHIN, TAKEMOTO
Format: Article
Language:English
Subjects:
Airway Resistance - physiology
Animals
Brain Stem - physiopathology
Cats
Decerebrate State
Electromyography
Female
Hypercapnia - physiopathology
Laryngeal Muscles - innervation
Laryngeal Muscles - physiopathology
Male
Pulmonary Alveoli - physiopathology
Pulmonary Ventilation - physiology
Space life sciences
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Summary:The larynx has three functions: phonation, airway protection, and respiration. Few studies have dealt with laryngeal respiratory function. To elucidate respiratory regulation by the larynx, we studied the changes in the activity of the intrinsic laryngeal muscles during hypercapnia in decerebrated cats. The electromyographic activities of the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were recorded simultaneously with an electromyogram of the diaphragm, endotracheal pressure, and concentrations of O 2 and CO 2 . The activity of the intrinsic laryngeal muscles during hypercapnia (end-tidal CO 2 , 8% to 10%) was analyzed in comparison with that during eucapnia. In hypercapnia, both the PCA and TA muscles increased their activities, and the endotracheal pressure during expiration was elevated to a higher level than that in eucapnia. TA muscle activities returned to the level during eucapnia after ligation of the common carotid arteries. These findings suggest that hypercapnia causes a further widening of the glottis during inspiration to decrease inspiratory resistance and a further narrowing of the glottis during expiration to prevent alveolar collapse. Thus it may be concluded that the larynx actively participates in respiratory regulation under the control of the brain stem through a process of peripheral inputs from the carotid receptors. (Otolaryngol Head Neck Surg 1998;118:537-44.)
ISSN:0194-5998
1097-6817
DOI:10.1016/S0194-5998(98)70215-3