PHARMACOLOGICAL ACTIONS OF A CONVULSANT BARBITURATE II. EFFECTS COMPARED WITH PENTOBARBITAL ON CEREBRAL CORTEX AND SOME BRAIN STEM SYSTEMS OF THE CAT

¹ Department of Pharmacology, University of Michigan, Ann Arbor

The actions of a convulsant barbiturate, sodium 5-ethyl, 5-(1,3-dimethylbutyl) barbiturate were compared with pentobarbital on EEG arousal, EEG recruitment, and on the spontaneous electrical activity of the partially neuronally isolated cerebral cortex preparation.

The convulsant barbiturate produces a transient low voltage, fast frequency EEG which is soon followed by medium voltage, medium frequency activity. EEG arousal elicited by electrical stimulation of the midbrain reticular formation is depressed by progressive doses of this agent.

EEG recruitment elicited by electrical stimulation of the diffuse thalamic projection system is initially reduced, and subsequently enhanced by small doses (2 mgm./kgm., i.v.) of the convulsant barbiturate. Larger doses depress these responses.

After small doses of the convulsant barbiturate there is an increase in the amplitude and a decrease in the frequency of spontaneous activity of the partially neuronally isolated cerebral cortex. Larger doses markedly diminish all activity.

Although important differences exist there is a remarkable similarity of action between pentobarbital and the convulsant barbiturate on these brain stem systems and cerebral cortex.