title: NOx- concentrations in the rat hippocampus and striatum have no direct relationship to anaesthesia induced by ketamine.
abstract: Using microdialysis, we have examined the effects of ketamine on concentrations of total nitric oxide oxidation products (NOx-) in the rat hippocampus and striatum in vivo to investigate the relationship between anaesthesia and NOx- production in the brain. Ketamine 25, 50 and 100 mg kg-1 i.p. increased NOx- concentrations to mean 125 (SD 13)%, 165 (11)% and 193 (13)% of basal, respectively, in the hippocampus and to 122 (12)%, 147 (7)% and 177 (14)% of basal in the striatum. Local perfusion with ketamine 50 and 100 mumol litre-1 into the hippocampus or striatum increased NOx- concentrations to 212 (32)% and 291 (17)% of basal, respectively, in the hippocampus and to 148 (20)% and 201 (18)% of basal in the striatum. Ketamine 50 and 100 mg kg-1 i.p. caused dose-dependent prolongation of loss of the righting reflex (LRR) and 100 mg kg-1 i.p. also caused loss of the corneal reflex (LCR). Local perfusion of ketamine did not provoke LRR or LCR. Inhibition of NOS by L-NAME 100 mg kg-1 i.p. decreased hippocampal NOx- concentrations to 58 (7)% of basal and did not provoke LRR or LCR. Although the effect of ketamine-induced increases in hippocampal NOx- concentrations was significantly depressed by L-NAME, LRR was not affected. These data imply that NOx- concentrations in the hippocampus or striatum have no direct relationship to the anaesthetic efficacy of ketamine, although this requires further investigation.
authors.affiliation: Department of Anaesthesiology, Yokohama City University School of Medicine, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Wu
authors.forename: T
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: F
authors.initials: F
authors.lastname: Okumura
mesh_terms: D000778:Anesthetics, Dissociative / Q000494:pharmacology*; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism*; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010084:Oxidation-Reduction / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000778:Anesthetics, Dissociative; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D007649:Ketamine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester