control animals and 360 u00b1 21 2 seconds with treated animals electroshock was produced in mice through the application of ear electrodes stimulation parameters which could induce the maximal electroshock seizure mes were adopted this was obtained by applying rectangular input shocks for 0 6 seconds each input lasted 0 4 ms and the input frequency was 25 sec phenobarbital sodium was used as the control substance it was injected intraperitoneally 10 minutes prior to the mes an amount of 250 mg kg of ap 28 was injected by the same route as phenobarbital sodium as shown in table 6 ap 28 was as effective as phenobarbital sodium intraperitoneal injection of 500 mg kg of ap 28 caused the electromyographic tracing to become flat in the rabbit with electrodes implanted in its cerebral cortex that effect was similar to the effect caused by 30 mg kg of intravenous phenobarbital sodium in the unrestrained cat with permanent electrodes implanted in the geniculate body hippocampus and cerebral cortex the concomitatant recording of eye movements and neck muscle contractions after doses of 500 or 1000 mg kg of ap 28 showed that sedation occurred without the electromyographic alterations which usually indicate sleep in cats having been conditioned to sleep for 8 hours from late morning 250 and 350 mg kg of ap 28 did not modify the total sleeping time but reduced the number of cases of rem sleep and the overall length of the period of time spent by the animal in sleeping did not change the period of time during which the animal sleep was characterized by slow waves was comparatively longer the effect of a single 500 mg kg oral dose of ap.