Dorsal root potentials in the cat: effects of bicuculline

Bicuculline (0.2 1 mg/kg) administered intravenously depressed dorsal root potentials (DRPs) evoked by stimulation of mixed, pure muscle or pure cutaneous nerves which was clearly concurrent with enhanced background potentials in intact cat. Administration of sodium pentobarbitone (15-30 mg/kg i.v.) reduced the ability of bicuculline to enhance background potentials and to depress evoked DRPs. In spinalized preparations, bicuculline depression of evoked DRPs by bicuculline in intact cat may not result from its action at axo-axonic GABAergic synapses alone and occlusion may also play a part. However, the role of gamma-aminobutyric acid (GABA) in primary afferent depolarization is confirmed in the spinalized preparations.