title: Central administration of nicotine suppresses tracheobronchial cough in anesthetized cats.
abstract: We tested the hypothesis that nicotine, which acts peripherally to promote coughing, might inhibit reflex cough at a central site. Nicotine was administered via the vertebral artery [intra-arterial (ia)] to the brain stem circulation and by microinjections into a restricted area of the caudal ventral respiratory column in 33 pentobarbital anesthetized, spontaneously breathing cats. The number of coughs induced by mechanical stimulation of the tracheobronchial airways; amplitudes of the diaphragm, abdominal muscle, and laryngeal muscles EMGs; and several temporal characteristics of cough were analyzed after administration of nicotine and compared with those during control and recovery period. (-)Nicotine (ia) reduced cough number, cough expiratory efforts, blood pressure, and heart rate in a dose-dependent manner. (-)Nicotine did not alter temporal characteristics of the cough motor pattern. Pretreatment with mecamylamine prevented the effect of (-)nicotine on blood pressure and heart rate, but did not block the antitussive action of this drug. (+)Nicotine was less potent than (-)nicotine for inhibition of cough. Microinjections of (-)nicotine into the caudal ventral respiratory column produced similar inhibitory effects on cough as administration of this isomer by the ia route. Mecamylamine microinjected in the region just before nicotine did not significantly reduce the cough suppressant effect of nicotine. Nicotinic acetylcholine receptors significantly modulate functions of brain stem and in particular caudal ventral respiratory column neurons involved in expression of the tracheobronchial cough reflex by a mecamylamine-insensitive mechanism.
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; and Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Institute of Medical Biophysics, Martin, Slovak Republic poliacek@jfmed.uniba.sk.
authors.forename: I
authors.initials: I
authors.lastname: Poliacek
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; and.
authors.forename: M J
authors.initials: MJ
authors.lastname: Rose
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; and.
authors.forename: T E
authors.initials: TE
authors.lastname: Pitts
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; and.
authors.forename: A
authors.initials: A
authors.lastname: Mortensen
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; and.
authors.forename: L W
authors.initials: LW
authors.lastname: Corrie
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; and.
authors.forename: P W
authors.initials: PW
authors.lastname: Davenport
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; and.
authors.forename: D C
authors.initials: DC
authors.lastname: Bolser
mesh_terms: D000009:Abdominal Muscles / Q000187:drug effects; D000777:Anesthetics / Q000494:pharmacology; D000818:Animals; D000996:Antitussive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001980:Bronchi / Q000187:drug effects*; D002415:Cats; D003371:Cough / Q000188:drug therapy*; D003964:Diaphragm / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D012018:Reflex / Q000187:drug effects; D012132:Respiratory Muscles / Q000187:drug effects; D014132:Trachea / Q000187:drug effects*
chemical_list: D000777:Anesthetics; D000996:Antitussive Agents; D009538:Nicotine
keywords: brain stem; mecamylamine; nicotinic receptors; ventral respiratory group