Effect of posture, route of respiration and negative pressure on
palatal muscle activity in man.
Mortimore, I. L., R. Mathur, and N. J. Douglas.
Respiratory Medicine Unit, University of Edinburgh, Edinburgh, EH3
9YW, Scotland, U.K.
APStracts 2:0136A, 1995.
Sleep apnea is worse in the supine posture and is associated with
retropalatal airway narrowing or occlusion. We have, therefore,
examined the effects of posture, negative pressure and route of
respiration on palatal muscle activity in 13 non-snoring, awake male
subjects using electromyography. Electromyographic activity of
levator palatini and palatoglossus was expressed as a percentage of
maximum activity. Both levator palatini (p=0.002) and palatoglossus
(p=0.002) exhibited phasic inspiratory activity. Overall, posture did
not affect levator palatini (F=1.58; p=0.23) or palatoglossus
(F=0.98; p=0.34) activity, but analysis by route of respiration
showed palatoglossus to be more active when nose breathing supine
(F=6.64; p=0.02). Levator palatini activity was lower when nose
breathing compared to mouth breathing both erect and supine (F=6.67;
p<0.02). Nose breathing with the mouth held open caused an increase
in palatoglossal activity (p=0.04). Negative pressure application (0
to -12.5 cm H20) caused significant increases in levator palatini
(p<0.001) and palatoglossus (p<0.001) activity, 100 msec after
pressure stimulus, irrespective of route. However, palatoglossus
required significantly greater negative pressures to cause activation
when applied via the nose compared to the mouth (P<0.05). These
observations indicate that levator palatini and palatglossus have
respiratory activity and are reflexly activated by negative pressure.
Received 15 August 1994; accepted in final form 21 March 1995.
APS Manuscript Number A856-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.