AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 3 572-R578, Copyright © 1990 by American Physiological Society
Forebrain rhythm generators influence sympathetic activity in anesthetized cats
M. J. Kenney, G. L. Gebber, S. M. Barman and B. Kocsis
Department of Pharmacology, Michigan State University, East Lansing 48824.
Autospectral and coherence analyses were used to study the frequency-domain
relationships between frontal-parietal cortical activity
[electroencephalogram (EEG)] and the discharges of the interior cardiac and
renal sympathetic nerves of baroreceptor-denervated and vagotomized cats
anesthetized with either alpha-chloralose or pentobarbital sodium. Delta
slow-wave activity in the EEG was correlated to sympathetic nerve discharge
(SND) as shown by sharp peaks between 0.5 and 4 Hz in the coherence
function. The relationship was stronger in chloralose- than in
pentobarbital-anesthetized cats. Coherence of the two signals could be
attributed to descending influences of forebrain delta slow-wave generators
on sympathetic circuits, since midbrain transection preferentially reduced
the power in SND at frequencies that cohered to the EEG before transection.
In contrast, the power in the EEG was not reduced by midbrain transection.
The relationship between cortical delta slow-wave activity and SND was
stronger during than between cortical spindlelike events that lasted 1-3 s
and recurred once every 5-10 s. These events were similar to cortical
spindles observed during the early stages of sleep and under light
barbiturate anesthesia. These observations raise the possibility that the
influences of forebrain delta slow-wave generators on SND are gated by
thalamic mechanisms normally involved in the sleep-wake cycle.
