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 receptor-mediated spontaneous (s) and evoked (e) excitatory postsynaptic currents (s/eEPSC and s/eEPSC) 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 and s/eEPSC by focal single- and/or paired-pulse electrical stimulation to compare them. The s/eEPSC showed smaller amplitude, slower rise time, and slower 1/e decay time constant (τ) than those of s/eEPSC. We previously examined how Xe modulates s/eEPSC, therefore, examined the effects on s/eEPSC in the present study. Xe decreased the frequency and amplitude of sEPSC, and decreased the amplitude but increased the failure rate and paired-pulse ratio of eEPSC without affecting their τ. It was concluded that Xe might suppress NMDA receptor-mediated synaptic transmission via both presynaptic and postsynaptic mechanisms.