title: Isoflurane suppresses central cardiac parasympathetic activity in rats: a pilot study.
abstract: BACKGROUND
  Intraoperative circulatory stability is a function of both cardiac parasympathetic activity and cardiac and vascular sympathetic activity; however, cardiac parasympathetic activity is rarely considered. This experiment addresses the effect of isoflurane on central cardiac parasympathetic control, i.e., cardiac vagal motoneurons (CVM), which are located in the nucleus ambiguous of the brain stem and project to the sinus node.
  
  
  METHODS
  In urethane-anesthetized rats, the single unit activity of CVM, antidromically identified from the craniovagal cardiac branch, was observed following the introduction of isoflurane. Isoflurane was introduced slowly over 10 minutes to achieve 2% end tidal CO2 (ETCO2)
  
  
  RESULTS
  Following the introduction of isoflurane (2% ETCO2), all CVM were almost entirely silenced (N=6 cells in 6 different rats, 1.9 ±2.4 vs. 0.2 ±0.3 Hz, P<0.05).
  
  
  CONCLUSIONS
  The data obtained with antidromically identified cardiac vagal motoneurons confirm data obtained previously with whole vagal nerve recordings. The authors speculate on how the blunting of the cardiac parasympathetic activity by isoflurane that was observed in rats may impact intraoperative circulatory stability in humans.
authors.affiliation: Physiology (CNRS UMR 5123), University of Lyon, Lyon, France.
authors.forename: E
authors.initials: E
authors.lastname: Toader
authors.forename: A
authors.initials: A
authors.lastname: Cividjian
authors.forename: L
authors.initials: L
authors.lastname: Quintin
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D006321:Heart / Q000187:drug effects* / Q000294:innervation*; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D009046:Motor Neurons / Q000187:drug effects; D010275:Parasympathetic Nervous System / Q000187:drug effects*; D010276:Parasympatholytics; D010865:Pilot Projects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014630:Vagus Nerve / Q000166:cytology / Q000187:drug effects
chemical_list: D018685:Anesthetics, Inhalation; D010276:Parasympatholytics; D002245:Carbon Dioxide; D007530:Isoflurane