title: Nicotine stimulation of the medulla increases blood flow of the common carotid artery in cats.
abstract: Microinjection of nicotine or glutamate into the dorsal facial area (DFA) of the medulla increases blood flow of common carotid artery (CCA). Whether there is a causal relationship between these two events is not known. Various agonists and antagonists for the nicotinic and glutamatergic receptors were microinjected through a four-barrel tubing into the DFA of anesthetized cats. Microinjections of nicotine [a non-selective nicotinic acetylcholine receptor (nAChR) agonist], choline (a selective alpha7-nAChR agonist), glutamate or KCl induced a modest increase in CCA blood flow. The nicotine- and choline-induced increases were reduced by alpha-bungarotoxin (an alpha7-nAChR antagonist) as well as MK-801 (a non-competitive NMDA receptor antagonist) or glutamate diethylester (a competitive AMPA/kainate receptor antagonist). The glutamate or KCl-induced increases were blocked by MK-801 and glutamate diethylester, but not by alpha-bungarotoxin. In conclusion, activation of nAChRs primarily via alpha7-nAChR caused a release of glutamate, which in turn activated NMDA and AMPA receptors, while cholinergic substance was not released into the DFA to activate the nicotinic receptor.
authors.affiliation: Neuro-Medical Scientific Center and Center for Vascular Medicine, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan.
authors.forename: Jon-Son
authors.initials: JS
authors.lastname: Kuo
authors.forename: Yuk-Man
authors.initials: YM
authors.lastname: Leung
authors.forename: Nai-Nu
authors.initials: NN
authors.lastname: Lin
authors.forename: Tony Jer-Fu
authors.initials: TJ
authors.lastname: Lee
authors.forename: Chi-Li
authors.initials: CL
authors.lastname: Gong
mesh_terms: D000818:Animals; D017536:Carotid Artery, Common / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D002415:Cats; D002794:Choline / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D018698:Glutamic Acid / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects* / Q000502:physiology; D008845:Microinjections; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000008:administration & dosage / Q000493:pharmacokinetics*; D018733:Nicotinic Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D020033:Protein Isoforms / Q000819:agonists; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors; D018092:Kainic Acid Receptors / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012039:Regional Blood Flow / Q000187:drug effects* / Q000502:physiology; D013268:Stimulation, Chemical
chemical_list: D002794:Choline; D018698:Glutamic Acid; D009538:Nicotine; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D020033:Protein Isoforms; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate