title: Response of respiratory muscles to intravenous nicotine challenge in anaesthetized cats.
abstract: The effects of an intravenous nicotine challenge on the ventilation and activity of rib cage muscles were studied in 33 pentobarbitone-chloralose anaesthetized cats. Bolus injection of nicotine (200 microg) into the right femoral vein evoked in 19 of the intact animals prompt, short-lived apnoea, or prolongation of the first expiration after the drug, the occurrence of which was significantly reduced by midcervical vagotomy (P < 0.001). In breaths that followed the apnoea, peak activity of the parasternal intercostal muscles increased from a baseline of 3.1 +/- 0.8 to 9.2 +/- 1.8 arbitrary units (P < 0.001). Nicotine produced a similar increase in peak phrenic ENG (7.0 +/- 0.5 to 14.5 +/- 1.2 arbitrary units; P < 0.001). Peak triangularis sterni muscle EMG was reduced from 8.9 +/- 1.2 to 6 +/- 1.7 arbitrary units (P < 0.05) and the onset of response was delayed to 30 s after the challenge. The changes of respiratory effectors induced by nicotine were independent of vagal integrity. The results show that post-nicotine apnoea is to large extent vagally dependent though the response of the respiratory muscles is mediated by non-vagal influences.
authors.affiliation: Department of Neurophysiology, Polish Academy of Sciences Medical Research Centre, Warsaw.
authors.forename: B
authors.initials: B
authors.lastname: Kopczyñska
authors.forename: M
authors.initials: M
authors.lastname: Szereda-Przestaszewska
mesh_terms: D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D004576:Electromyography; D005260:Female; D007275:Injections, Intravenous; D007366:Intercostal Muscles / Q000502:physiology; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D010791:Phrenic Nerve / Q000187:drug effects / Q000502:physiology; D015656:Respiratory Mechanics / Q000187:drug effects; D012132:Respiratory Muscles / Q000187:drug effects*; D013990:Tidal Volume / Q000187:drug effects; D014628:Vagotomy
chemical_list: D018722:Nicotinic Agonists; D009538:Nicotine