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 _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 (τ _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 paired-pulse ratio of eEPSC _NMDA without affecting their τ _Decay . It was concluded that Xe might suppress NMDA receptor-mediated synaptic transmission via both presynaptic and postsynaptic mechanisms.
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