Effects of ketamine against strychnine-induced convulsions and the determination of its ED_(50) in mice

Objective To determine the effects of ketamine and its 50% effective dose(ED50) during its therapeutic use against strychnine-induced convulsions in mice.Methods Kunming mice randomly divided into six groups(n=10) were given intraperitoneal injection of saline 0.1 ml/10 g or doses of ketamine(24.5,35.0,50.0,71.4 and 102.0 mg/kg),respectively.5 minutes later,0.1 ml/kg of 1.5 mg/kg strychnine nitrate was administered i.p.to observe the incidence of seizures in mice,latency,duration of tonic state and mortality,and to determine the anticonvulsant ED50 of ketamine against strychnine-induced convulsions in mice using sequential method and spot-slope method.Results Compared with the NS group,the incidences of seizures decreased in K50.0,K71.4 and K102.0 groups(P0.05,P0.01);the mortalities significantly decreased in K35.0,K50.0,K71.4 and K102.0 groups(P0.05,P0.01),the seizure latencies were prolonged in all groups(P0.05,P0.01);in a dose-dependent manner each group can be shortened seizure latency(P0.05,P0.01),and a dose-dependent manner(r=0.9740,P0.01).The 95% authentic range of ketamine ED50 against strychnine convulsion was 44.8-64.3 mg/kg by the grouping method and 39.3-74.8 mg/kg by the sequential method.Conclusion The anticonvulsant mechanisms of ketamine may be associated with glycin receptor.