Long term facilitation of upper airway muscle activities in
vagotomized and vagally intact cats.
Mateika, J. H., and R. F. Fregosi.
Department of Physiology, The University of Arizona, Health
Sciences Center, Tucson, AZ, 85721-0093
APStracts 3:0462A, 1996.
The primary purpose of the present investigation was to determine if
long-term facilitation (LTF) of upper airway muscle activities occurs
in vagotomized and vagally intact cats. Tidal volume and diaphragm,
genioglossus and nasal dilator muscle activities were recorded
before, during and after one carotid sinus nerve was stimulated 5
times with 2 minute trains of constant current. Sixty minutes after
stimulation nasal dilator and genioglossus muscle activities were
significantly greater than control in the vagotomized cats, but not
in the vagally intact cats. Tidal volume recorded from the
vagotomized and vagally intact cats was significantly greater than
control during the post-stimulation period. In contrast, diaphragm
activities were not significantly elevated in the post-stimulation
period in either group of animals. We conclude that: 1) LTF of
genioglossus and nasal dilator muscle activities can be evoked in
vagotomized cats; 2) vagal mechanisms inhibit LTF in upper airway
muscles and 3) LTF can be evoked in accessory inspiratory muscles,
since LTF of inspired tidal volume was greater than LTF of diaphragm
activity.
Received 22 May 1996; accepted in final form 27 September 1996.
APS Manuscript Number A481-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996