Control of nasal dilator muscle activities during exercise: role of
nasopharyngeal afferents.
Sullivan, Jenna, David Fuller, and Ralph F. Fregosi.
Department of Exercise and Sport Sciences and Department of
Physiology, The University of Arizona, Tucson, AZ, 85721
APStracts 2:0559A, 1995.
Our primary aim was to determine if reducing the activity of nasal
airway receptors would influence drive to the nasal dilator muscles
(NDM) during exercise. We used lidocaine (2%) or nasal splints to
diminish afferent airway receptor activity, and measured the EMG
activity of the NDMs during incremental bicycle exercise in subjects
that breathed nasally. NDM EMG activities increased as a function of
exercise intensity, but were not changed by lidocaine and only
slightly reduced by splinting. Similarly, neither intervention
altered the normal decrease in NDM EMG activity associated with
reductions in airway resistance evoked by He:O2 breathing. We also
compared the NDM EMG response to exercise with that evoked by CO2
rebreathing at rest, to determine if the nature of the ventilatory
stimulus influences drive to the NDM; comparisons were made at
constant levels of nasal VI, and therefore constant total ventilatory
output. The increase in EMG activity was much higher during exercise
compared to hyperoxic hypercapnia. In conclusion: 1) desensitizing
the nasal airway does not alter NDM activity significantly during
exercise; 2) exercise results in much greater increases in NDM
activity compared to hypercapnia, indicating that different
ventilatory stimuli can evoke more or less activation of upper airway
motoneurons, even when comparisons are made at constant levels of
total ventilatory output.
Received 26 June 1995; accepted in final form 12 December 1995.
APS Manuscript Number A683-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95