Effect of phenobarbital on cortical after-discharge and overt seizure patterns in the cat

Abstract

The effect of phenobarbital on the duration of cortical after-discharge and the overt seizure patterns was evaluated in cats with chronically implanted electrodes. In addition, the effect of paralyzation on the after-discharge duration as well as the effects of phenobarbital in the paralyzed state were measured. The cats were separated into two groups on the basis of the severity of the overt component of the seizure. The overt seizures of the Group I animals were more severe than those of the Group II animals. In Group I cats, the duration of cortical after-discharge was significantly prolonged after 10 mg kg of phenobarbital, although the overt component of the seizure was depressed. After 20 mg kg, both the overt and electrical patterns were depressed. In Group II, only a depression of both the seizure duration and overt component was observed (after 10 mgkg of phenobarbital). In all cats, the after-discharge duration was significantly longer when the animals were paralyzed with gallamine triethiodide. Such an increase was not observed when succinylcholine was used as the paralyzing agent. In the paralyzed (gallamine triethiodide) state, 10 mg kg of phenobarbital significantly depressed the after-discharge duration in the Group I animals. In Group II, 5 mg kg of phenobarbital had no effect in the paralyzed state.