Objective:To explore the effects of glutamate and the NMDA receptor on the outward K+ currents,and illustrate the mechanisms for glutamate induced neuronal damage. Methods: Neurons were collected from18-day-old embryonic rats in the present work and were divided into two groups:the control and glutamate treated group. The currents were recorded by performing the whole cell patch clamp,and subsequently the cell morphous as well as neuron apoptosis were evaluated by morphology and TUNEL assay. Results: Glutamate obviously increased the outward K+ currents and MK-801,the NMDA receptor antagonist,significantly alleviated the outward K+ currents. The morphology and TUNEL results revealed that the treatment of glutamate resulted in neuronal damage (P < 0.01) while MK-801,the blocker of K+ channel TEA,as well as high concentration of K+ solution substantially reduced the cell damage(P < 0.01). Conclusion: The outward K+ currents were involved in neuronal damage induced by glutamate,and the mechanisms need further clarified.