Role of the brain stem in generating the 2- to 6-Hz oscillation in sympathetic nerve discharge.
We tested the hypothesis that brain stem circuits normally generate a 2- to 6-Hz oscillation in sympathetic nerve discharge (SND). Experiments were performed on baroreceptor-denervated decerebrate cats and urethan-anesthetized rats in which renal or splanchnic SND was recorded along with field potentials (population activity) from sites in the rostral ventrolateral medulla, medullary raphe, or medullary lateral tegmental field. Our major findings were as follows. 1) Population activity recorded from the three medullary regions contained a 2- to 6-Hz oscillation. 2) The 2- to 6-Hz oscillation in population activity recorded from some medullary sites was correlated to that in SND. Peak coherence in the 2- to 6-Hz band approached a value of 1 in some cases. 3) Whereas cervical spinal cord transection abolished or markedly reduced SND, the 2- to 6-Hz oscillation in medullary activity was essentially unchanged. These results support the view that the 2- to 6-Hz oscillation in SND can be generated in the brain stem of cats and rats.
Zhong
S
S
Department of Pharmacology/Toxicology, Michigan State University, East Lansing 48824-1317.
Huang
Z S
ZS
Gebber
G L
GL
Barman
S M
SM
D000818:Animals; D001933:Brain Stem / Q000502:physiology*; D002415:Cats; D003655:Decerebrate State; D004558:Electric Stimulation; D005260:Female; D007668:Kidney / Q000294:innervation; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009991:Oscillometry; D010791:Phrenic Nerve / Q000502:physiology; D011311:Pressoreceptors / Q000502:physiology; D011903:Raphe Nuclei / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013116:Spinal Cord / Q000502:physiology; D013153:Splanchnic Nerves / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*; D013681:Tegmentum Mesencephali / Q000502:physiology; D013997:Time Factors; D014630:Vagus Nerve / Q000502:physiology