Article date: 1991/5/10
PubMed ID: 1678299
Journal name: Brain research (ISSN: 0006-8993)
We have found a medullary vasodepressor area in cat centered 3 mm rostral to the obex and just lateral to the compact division of the ambiguus nucleus. The area is compact, extending at most 1 mm in any direction. Microinjection of L-glutamate into this rostral depressor area (RDA) elicited acute hypotension and bradycardia. These responses were not reduced by either peripheral atropine blockade or bilateral vagotomy, but they were nearly abolished by peripheral phentolamine/propranolol blockade or high cervical cord transection. Bilateral reversible blockade of the RDA by local microinjection of the neuronal hyperpolarizing agent muscimol yielded chronic hypertension and tachycardia. Sympathetically mediated baroreflex, observed as a bradycardic response to a peripherally administered phenylephrine bolus in atropinized animals, was partially (50%) abolished during this same blockade. We conclude that the RDA contains sympathoinhibitory cells which are involved in the regulation of cardiovascular tone and in the expression of the sympathetic component of baroreflex.
Author List: Dempesy C W, Cusick C G, Fontana C J, Richardson D E
Publication Types: Journal Article
Substances mentioned in the article: Glutamates; Receptors, Adrenergic; Receptors, Muscarinic; Muscimol; Glutamic Acid; Atropine; Propranolol; Phentolamine;
Mesh terms: Animals; Atropine/administration & dosage; Blood Pressure/drug effects; Cats; Electric Stimulation; Female; Glutamates/administration & dosage; Glutamic Acid; Heart Rate/drug effects; Male; Medulla Oblongata/drug effects; Microinjections; Muscimol/administration & dosage; Phentolamine/administration & dosage; Pressoreceptors/drug effects; Propranolol/administration & dosage; Receptors, Adrenergic/drug effects; Receptors, Muscarinic/drug effects; Reflex/physiology; Sympathetic Nervous System/physiology; Vagotomy;