THE EFFECT OF PHENOBARBITAL ON AUTONOMIC FUNCTION AND EPILEPTOGENIC ACTIVITY-INDUCED BY THE HIPPOCAMPAL INJECTION OF PENICILLIN IN CATS

This study addressed whether penicillin-induced epileptiform discharge s in the right hippocampus produced associated autonomic dysfunction. The study also examined the effect of phenobarbital on the heart rate and blood pressure changes that were induced by the epileptiform disch arges. The delay in onset of epileptiform activity at the site of inje ction ranged from 1 second to 16 minutes, and consisted of interictal discharges or ictal discharges. With the onset of epileptiform activit y, blood pressure and heart rate increased significantly from control (P < .05). Electrocardiogram alterations included: P-R interval change s; increased P-wave amplitude; QRS complex changes; T-wave inversion; and ST elevation. Phenobarbital 20 mg/kg intravenously suppressed the epileptogenic activity and depressed the blood pressure and heart rate below control (P < .05). In an additional series of experiments, peni cillin G injected into the right hippocampus in five cats produced epi leptiform activity and,increased the blood pressure and the heart rate significantly from the control (P < .05). Phenobarbital (20 mg/kg, in travenously, and 40 mg/kg, intravenously) also prevented the penicilli n-induced epileptiform activity. Phenobarbital (40 mg/kg, intravenousl y) reversed the effect of penicillin on the blood pressure and heart r ate, to levels significantly below that of control (P < .05). Phenobar bital diminished both epileptiform activity and autonomic dysfunction. The autonomic dysfunction related to epileptiform activity induced by focal hippocampal administration of penicillin was similar to that in duced by the intravenous administration of pentylenetetrazol.