AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 3 317-R322, Copyright © 1985 by American Physiological Society
Metabolic mapping of a cardiac reflex mediated by sympathetic ganglia in dogs
D. R. Kostreva, J. A. Armour and Z. J. Bosnjak
The hypothesis tested was that some cardiac reflexes can be mediated by the
neural mechanisms in thoracic sympathetic ganglia in addition to those
existing in the spinal cord or brain stem. In mongrel dogs anesthetized
with pentobarbital sodium the left stellate (SG) and middle cervical (MCG)
ganglion were decentralized, and the left thoracic vagosympathetic trunk
was cut cranial to the MCG and caudal to the MCG but above the heart. The
left thoracic vagosympathetic trunk below the MCG was then stimulated
afferently. A single bolus of 2-[14C]deoxyglucose was injected
intravenously and the stimuli repeated periodically toward the
decentralized ganglia for 45 min. The heart and ganglia were then removed,
frozen, and sectioned for autoradiography. Significant increases in glucose
utilization were found in both the SG and MCG compared with ganglia from
nonstimulated control animals. Significant increases in the glucose
utilization of the endocardial third of the left ventricle were also
observed in the reflexly stimulated hearts. Neural mechanisms in the
acutely decentralized SG and MCG could modify cardiac glucose utilization
within specific areas of the heart. In addition, such ganglionic mechanisms
may be concentrated within the caudal half of the SG. These data suggest
that many neurons in the thoracic autonomic ganglia may be involved in
local cardiac reflexes.
