AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 4 681-R686, Copyright © 1984 by American Physiological Society
Vagal inhibition of respiratory-linked efferent activity in the carotid sinus nerve
D. R. Kostreva, G. L. Palotas and J. P. Kampine
The hypothesis tested in this study was that glossopharyngeal efferent
nerve activity coursing through the carotid sinus nerve has a central
origin. Efferent activity in the carotid sinus nerve exhibited a
respiratory rhythm in spontaneously breathing, closed-chest, mongrel dogs
anesthetized with pentobarbital sodium (30 mg/kg iv). Carotid sinus nerve
activity was recorded from the intact or cut central end of the carotid
sinus nerve. Diaphragm electromyogram (D-EMG), carotid sinus pressure,
systemic blood pressure, and electrocardiogram were also recorded. Before
vagotomy, small increases in carotid sinus efferent nerve activity (CSENA)
synchronous with increases in the D-EMG were observed during spontaneous
inspiration. Section of the contralateral cervical vagosympathetic trunk
markedly potentiated the increases in CSENA. Bilateral superior cervical
ganglionectomy or nodose ganglionectomy failed to alter the increases in
CSENA. Section of the ipsilateral glossopharyngeal nerve near the skull
abolished the CSENA. This study demonstrates that respiratory-modulated
glossopharyngeal efferents course through the carotid sinus nerve to the
carotid sinus or carotid body. These efferents may be part of a central
respiratory regulatory mechanism that may rapidly alter the sensitivity of
the carotid sinus baroreceptors and/or carotid body receptors on a
breath-to-breath basis.
