Dexmedetomidine reduces seizure threshold during enflurane anaesthesia in cats

Dexmedetomidine is an alpha(2) agonist and has been reported to have procon vulsant actions. To investigate the interaction of dexmedetomidine with con vulsant anaesthetics, we studied effects on seizure threshold in cats durin g enflurane anaesthesia. Cats were prepared with chronic implantation of el ectrodes for recording of the cortical electroencephalogram (EEG) and midbr ain reticular formation multi-unit activity (R-MUA). Seizure threshold, the reciprocal of the number of electrical stimuli required to induce generali zed EEG seizure activity x 1000 (seizure induction index (SII)), was assess ed. The effects of dexmedetomidine 1, 10 and 100 mu g kg(-1) i.v. and yohim bine 500 mu g kg(-1), an at antagonist, on SII during 3.5% enflurane anaest hesia were investigated. Dexmedetomidine significantly increased SII at 10 and 100 mu g kg(-1), and this effect was reversed by yohimbine. We found th at high-dose dexmedetomidine reduced seizure threshold during enflurane ana esthesia.