AJP - Regulatory, Integrative and Comparative Physiology, Vol 246, Issue 3 354-R358, Copyright © 1984 by American Physiological Society
Peripheral neural input to neurons of the middle cervical ganglion in the cat
Z. J. Bosnjak and J. P. Kampine
In vitro studies were conducted on the middle cervical ganglion (MCG) of
the cat by recording intracellular action potentials from its neurons. The
purpose of this study was to examine the possibility of a peripheral
synaptic input to the MCG. Preganglionic electrical stimulation, via the
ventral ansa (VA) and dorsal ansa (DA) subclavia, and post-ganglionic
electrical stimulation, via the ventrolateral cardiac nerve (VCN), evoked
graded synaptic responses that led to the discharge of one or more action
potentials in the 14 ganglia studied. The conduction velocity of these
pathways ranged from 0.4 to 0.9 m/s. Ten percent of the cells impaled were
inexcitable, even with direct intracellular depolarizing current, whereas
80% of the neurons studied received a synaptic input from fibers of both
central and peripheral origin. In addition, subthreshold synaptic inputs
from peripheral and central origin sum to discharge the cell, suggesting an
integration of neural inputs in the MCG. These responses were blocked by
d-tubocurarine chloride. This evidence indicates that sympathetic efferent
nerve activity can be modified by peripheral excitatory inputs and that
these inputs may function as pathways for a peripheral reflex at the level
of the MCG.
