Effects of pentobarbitone, ketamine and lignocaine on synaptic transmission in the rat olfactory cortex in vitro

The effects of pentobarbitone, ketamine and lignocaine on synaptic transmission in the rat olfactory cortex were studied. All agents depressed the presynaptic spike, the excitatory postsynaptic potential (EPSP) and the population spike evoked by stimulation of the lateral olfactory tract in a concentration-dependent manner. However, each anaesthetic had different effects on the processes of excitatory synaptic transmission. Pentobarbitone depressed primarily the EPSP, ketamine primarily the excitability of the presynaptic fibres and lignocaine the excitability of the presynaptic fibres; lignocaine also reduced the release of excitatory transmitters. None of the three agents influenced the passive membrane properties or the excitability of olfactory pyramidal cells. These data indicate that these agents block synaptic transmission in the olfactory cortex by different mechanisms.