Effects of muscle relaxants on EEG, ABR and EMG in rabbits

The effects of baclofen and pancuronium bromide on evoked electromyogram (E MG), cortical electroencephalogram (EEG) and auditory brainstem responses ( ABR) were studied in pentobarbital anesthetized normal rabbits. Evoked EMG was measured in the gastrocnemius muscle by electrical stimulation of the s ciatic nerve. Intravenous injection of baclofen decreased EEG and arterial blood pressure and light reflex, however, it had no significant influence o n EMG or ABR at doses of 10 and 20 mg/kg/h. Pancuronium bromide immediately inhibited respiration, decreased EEG and EMG, however, it had no significa nt influence on arterial blood pressure, ABR, or light reflex, at doses of 0.4 and 1.0 mg/kg/h in anesthetized rabbits. ABR waves were observed until just before cardiac arrest with both of the muscle relaxants. It is suggest ed that ABR are not influenced by central or peripheral muscle relaxants, o r by pentobarbital.