Synaptic effects of xenon on NMDA receptor-mediated response in rat spinal neuron

To investigate the precise mechanism of xenon (Xe), pharmacologically isolated AMPA/KA and NMDA receptormediated spontaneous (s) and evoked (e) excitatory postsynaptic currents (s/eEPSC AMPA/KA and s/eEPSC NMDA ) were recorded from mechanically isolated single spinal sacral dorsal commissural nucleus (SDCN) neurons attached with glutamatergic nerve endings (boutons) using conventional whole-cell patch-clamp technique. We analysed kinetic properties of both s/eEPSC AMPA/KA and s/eEPSC NMDA by focal single- and/or paired-pulse electrical stimulation to compare them. The s/eEPSC NMDA showed smaller amplitude, slower rise time, and slower 1/e decay time constant ( tau Decay ) than those of s/eEPSC AMPA/KA . We previously examined how Xe modulates s/eEPSC AMPA/KA , therefore, examined the effects on s/eEPSC NMDA in the present study. Xe decreased the frequency and amplitude of sEPSC NMDA , and decreased the amplitude but increased the failure rate and pairedpulse ratio of eEPSC NMDA without affecting their tau Decay . It was concluded that Xe might suppress NMDA receptormediated synaptic transmission via both presynaptic and postsynaptic mechanisms.