Tonic drive to sympathetic premotor neurons of rostral ventrolateral medulla from caudal pressor area neurons
Campos, R.R.; McAllen, R.M.
American Journal of Physiology 276(4): R1209-R1213
1999
ISSN/ISBN: 0002-9513 PMID: 10198405 Document Number: 502905
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. Reprinted by permission of the publisher.