title: Tonic drive to sympathetic premotor neurons of rostral ventrolateral medulla from caudal pressor area neurons.
abstract: The responses of sympathetic premotor neurons in the rostral ventrolateral medulla (RVLM) to activation or inactivation of neurons in the caudal pressor area (CPA) were studied in urethan-anesthetized rats. Extracellular recordings were made from 32 barosensitive single units in the RVLM, of which 26 were antidromically activated from the cervical cord. Unilateral microinjections of L-glutamate (0.5-5 nmol) into the CPA increased firing in 13 of 14 premotor neurons by 90 +/- 30% while raising blood pressure. Both ipsilateral and contralateral injections were effective. Unilateral or bilateral inhibition of CPA neuron activity by microinjecting glycine (5-200 nmol/side) lowered blood pressure, while it reduced firing in 9 of 10 and 16 of 17 premotor neurons, respectively, by 45 +/- 9 and 39 +/- 6%. A significant proportion of tonic activity in RVLM sympathetic premotor neurons is thus driven, directly or indirectly, by neurons in the CPA.
authors: Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville 3052, Australia. rmca@hfi.unimelb.edu.au
authors: R R
authors: RR
authors: Campos
authors: R M
authors: RM
authors: McAllen
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D001933:Brain Stem / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000494:pharmacology; D005998:Glycine / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000502:physiology*; D008845:Microinjections; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000166:cytology / Q000502:physiology*
chemical_list: D018698:Glutamic Acid; D005998:Glycine