In the preliminary experiment, it was recognized that the whole brain of the mouse, rabbit, rat, guinea-pig and frog contained only the specific cholinesterase (ChE). The ChE activity was determined by the titration method of
Hall & Lucas. After the injection of various drugs and when toxic signs or death appeared, the mice were decapitated and their brain ChE activity was determined. DFP, eserine, prostigmine, camphor and evipan-Na decreased the brain ChE activity. Strychnine, caffein, picrotoxine, coramin, cardiazol, atropine, nicotine, methylpropamine, benadryl, 3015 R.P., cocaine, morphine, demerol, barbital sodium, tridione and urethane did not modify it. Fur thermore, the influence of various drugs on the mice was studied, of which brain ChE activity was decreased to 20 ?? 30% of normal value by the injection of DFP. Those mice tolerated to the lethal dose of strychnine and brucine, but did not tolerate to that of caffein, cardiazol and picrotoxine. And potentiated effect of DFP upon the analgesic action of morphine was found. The above results suggest that the relation between the convulsant or anticonvulsant agents and the activity of the brain ChE is not so intimate.
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