An Electrophysiological Study on the Effects of Ketamine in the Central Nervous System III

Effects on Autonomic Nervous Acti vity and EEG Topography

Abstract

To study the effects of ketamine hydrochloride (hereafter, ketamine) on the autonomic nervous system, experiments on intestinal movement, heart rate and mean blood pressure were conducted in rabbits.
EEG topogra phy by a minicomputer system (ATAC-3700) was performed in order to investigate the effect of ketamine on the EEG activity, too.
1) Administration of ketamine induced no significan t change in intestinal movement.
2) Ketamine tended to decrease the inhibitory effect on intestinal movemen t as a result of stimulation of the brainstem reticular formation.
3) In the rabbit, there was no sign ificant change in the heart rate or blood pressure following administration of ketamine (0.3-5.0mg/kg), but the heart rate and blood pressure decreased with administration of ketamine (10.0mg/kg), which resulted in decreases of 9.6% in the heart rate and 15.5% in the blood pressure.
4) Administration of ketam ine (0.3-0.5mg/kg) resulted in no change in either power (V) or power ratio (%) in delta and theta bands, but resulted in tendency to increase in both power (V)and power ratio (%) in betal and beta2 bands. These EEG findings support the prev ious reports which shows that administration of small doses of ketamine (0.3-0.5mg/kg) somewhat elevates the level of consciousness.
5) Administration of ketamine (0.3-10.0mg/kg) resulted in an increase in power (V) in all bands and tendency to increase in power ratio (%) in betal and beta2 bands.