title: Involvement of ATP-sensitive K(+) channels in the peripheral antinociceptive effect induced by ketamine.
abstract: OBJECTIVE
  To investigate the contribution of K(+) channels on peripheral antinociception induced by ketamine.
  
  
  METHODS
  Prospective experimental study.
  
  
  METHODS
  110 male Wistar rats weighing 160-200 g.
  
  
  METHODS
  The paw pressure required to elicit limb flexion was designated as the nociceptive threshold. Hyperalgesia was induced by intraplantar injection of prostaglandin E2 . All drugs were administered locally into the right hind paw of rats. Ketamine was administered into the right hind paw 2 hours and 55 minutes after local injection of PGE2 . Tetraethylammonium was administered 30 minutes prior to ketamine and the other K(+) channel blockers, glibenclamide, dequalinium and paxilline, were administered 5 minutes prior to ketamine.
  
  
  RESULTS
  Prostaglandin E2 (2 μg per paw) induced hyperalgesia. Ketamine (10, 20, 40 and 80 μg per paw) elicited a local peripheral antinociceptive effect that was antagonized by a specific blocker of ATP-sensitive K(+) channels, glibenclamide (20, 40 and 80 μg per paw). In another experiment, the non-selective voltage-dependent K(+) channel blocker tetraethylammonium (30 μg per paw) and small and large conductance blockers of Ca(2+) -activated K(+) channels, dequalinium (50 μg per paw) and paxilline (20 μg per paw), were ineffective at blocking the effect of a local ketamine injection.
  
  
  CONCLUSIONS
  Analysis of these results provides evidence that ketamine, may in part, induce peripheral antinociceptive effects by ATP-sensitive K(+) channel pathway activation.
authors.affiliation: Department of Pharmacology, Institute of Biological Sciences, ICB-UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Thiago R L
authors.initials: TR
authors.lastname: Romero
authors.forename: Igor D G
authors.initials: ID
authors.lastname: Duarte
mesh_terms: D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D054086:KATP Channels / Q000378:metabolism*; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010146:Pain / Q000188:drug therapy*; D011312:Pressure; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000700:Analgesics; D054086:KATP Channels; D007649:Ketamine