Forced oscillations in sympathetic nerve discharge.
Periodic electrical stimulation of the medullary raphe or lateral tegmental field in baroreceptor-denervated cats was used to force the central systems responsible for the 10-Hz and 2- to 6-Hz rhythms in post-ganglionic sympathetic nerve discharge (SND). The 10-Hz rhythm in SND could be entrained either to the frequency of medullary stimulation or to harmonics of the stimulus frequency. The harmonic of the stimulus frequency to which the 10-Hz rhythm was entrained in one postganglionic nerve could be different from that in another nerve. On this basis, we propose that the circuits responsible for the 10-Hz rhythms in SND may be modeled as a system of coupled nonlinear oscillators, each of which either influences one postganglionic nerve or nonuniformly affects different postganglionic nerves. The relatively wide band 2- to 6-Hz component in SND could be forced into a stable oscillatory state by medullary stimulation at frequencies between 3 and 5 Hz. This observation is consistent with the view that the 2- to 6-Hz component reflects the complex behavior of a nonlinear oscillator rather than the output of a physiological noise generator.
Huang
Z S
ZS
Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824-1317.
Gebber
G L
GL
Zhong
S
S
Barman
S M
SM
D000818:Animals; D002415:Cats; D003655:Decerebrate State; D003714:Denervation; D004558:Electric Stimulation; D004594:Electrophysiology; D008526:Medulla Oblongata / Q000502:physiology; D009991:Oscillometry; D010507:Periodicity; D011311:Pressoreceptors / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*