AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 2 400-R407, Copyright © 1994 by American Physiological Society
Coordination of the cardiac-related discharges of sympathetic nerves with different targets
G. L. Gebber, S. Zhong, S. M. Barman and H. S. Orer
Department of Pharmacology/Toxicology, Michigan State University, East Lansing 48824-11317.
Partial coherence analysis was used to remove the influences of
pulse-synchronous baroreceptor nerve activity (as reflected by the arterial
pulse) on the coherence of the cardiac-related discharges of sympathetic
nerve pairs in unanesthetized decerebrate cats. It can be predicted that
the peak at the heart rate frequency in the ordinary coherence function
relating the discharges of two nerves will be eliminated by either
partialization using the arterial pulse or surgical baroreceptor
denervation, if the central circuits controlling the nerves share
baroreceptor inputs but are not interconnected. Contrary to this
prediction, in many experiments the peak was not eliminated by
partialization using the arterial pulse. Moreover, partialization often
nonuniformly reduced the peaks at the heart rate frequency in the coherence
functions for different nerve pairs. These results are consistent with a
model of multiple routes over which baroreceptor influences are distributed
to the central circuits controlling different sympathetic nerves.
Specifically, we propose that the direct route from the baroreceptors to
each of the central circuits is complemented by cross talk among the
central circuits.
