JOURNAL OF OSAKA DENTAL UNIVERSITY

Vol. 42 No. 1      APRIL - 2008

ISSN: 0475-2058      UBIC: 172

SUMMARY

We evaluated differences in CNS electrical activity immediately before and during convulslons in animals receiving intravenous administration of lidocaine, pentylenetetrazole (PTZ), and picrotoxin. Based on typical electroencephalogram (EEG) changes, this study characterized the relationship between electrical activity and regional cerebral blood flow (r-CBF) immediately before and during convulsions among animals receiving lidocaine and the two CNS stimulants. Thirty-six Japanese white rabbits were anesthetized and mean arterial pressure (MAP) was monitored. They were randomly allocated to three groups of 12 each: lidocaine 4.0 mg/kg/min, PTZ 5.0 mg/kg/min, or picrotoxin 0.5 mg/kg/min. Test drugs were administered intravenously until EEG seizure activity developed. In experiment 1, cortical r-CBF was monitored using laser Doppler flowmetry, and cisterna magna pressure (CMP) and EEG were monitored. Experiment 2 was performed based on typical EEG changes observed in the first experiment to determine r-CBF in five regions of the brain using colored microspheres and to observe changes in partial oxygen pressure (PtO2) before and during convulsions. In experiment 1, tetraphasic changes were observed in the EEG before and during convulsions in the lidocaine group, while in the PTZ and picrotoxin groups triphasic changes were observed. In the PTZ and picrotoxin groups, MAP during convulsions was significantly increased to at least 1.5 times the baseline value. In the PTZ and picrotoxin groups, CMP and cortical r-CBF were increased substantially during convulsions, while in the lidocaine group CMP alone was increased compared with the baseline. In experiment 2, r-CBF increased during wave discharges in all five regions in the PTZ group, but only in the right hemisphere in the lidocaine and picrotoxin groups. PtO2 increased during reoccurrence of slow waves in the lidocaine group, but not in the PTZ or picrotoxin groups. We concluded that CNS electrical activity before and during convulsions differed between the lidocaine and CNS stimulants. During drug-induced convulsions, r-CBF differed between the two drug classes, although homeostasis of PtO2 was maintained in ah groups. (J Osaka Dent Univ 2008; 42: 17-26) Key words: Lidocaine; Convulsions; Cerebral circulation; Electroencephalogram activity.

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