title: Do dopamine receptors mediate part of MAC?
abstract: BACKGROUND
  Depletion of central nervous system catecholamines, including dopamine, can decrease MAC (the minimum alveolar concentration of an inhaled anesthetic required to suppress movement in response to a noxious stimulus in 50% of test subjects); release of central nervous system catecholamines, including dopamine, can increase MAC; and increased free dopamine concentrations in the striatum can decrease MAC. Such findings suggest that dopamine receptors might mediate part of the capacity of inhaled anesthetics to provide immobility in the face of noxious stimulation.
  
  
  METHODS
  We measured the effect of blockade of D2 dopamine-mediated transmission with 0.3 mg/kg or 3.0 mg/kg droperidol on the MAC of cyclopropane, desflurane, halothane, isoflurane, or sevoflurane in rats, and the effect of 3.0 mg/kg droperidol on the dose or concentration of etomidate (an anesthetic known to act principally by enhancing the response of gamma-aminobutyric acid(A) receptors to gamma-aminobutyric acid) required to suppress movement in response to noxious stimulation.
  
  
  RESULTS
  Blockade of D2 dopamine-mediated transmission with droperidol does not decrease the MAC of cyclopropane, desflurane, halothane, isoflurane, or sevoflurane or its equivalent for etomidate in rats.
  
  
  CONCLUSIONS
  These data, plus data from studies by others about D1 dopamine receptors, indicate that dopamine receptors do not mediate the immobility produced by inhaled anesthetics.
authors.affiliation: Department of Anesthesia, University of California, San Francisco, CA 94143-0464, USA.
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Tanifuji
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Mark
authors.initials: M
authors.lastname: Liao
authors.forename: Edmond I
authors.initials: EI
authors.lastname: Eger
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Laster
authors.forename: James M
authors.initials: JM
authors.lastname: Sonner
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D000077335:Desflurane; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006221:Halothane / Q000494:pharmacology; D007530:Isoflurane / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000502:physiology*
chemical_list: D018685:Anesthetics, Inhalation; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; D000077335:Desflurane; D007530:Isoflurane; D006221:Halothane