Introduction: Transient receptor potential vanilloid 4 receptor (TRPV4R) may be over-activated by cell-swelling etc.during the stroke.For this reason, we explored the effect of blocking TRPV4R on the infarct volume in middle cerebral artery occlusion (MCAO) mice using TTC staining.We also measured NMDA-induced current (INMDA) using patch clamp recording when TRPV4R was activated in hippocanpal CA1 pyramidal neurons.Results: TRPV4R antagonist ruthenium red (RR) decreased the infarct volume at 24 hr post-MCAO when RR was firstly intracerebroventricular (icy.) injected at 1 hr or 4 hrs post-MCAO and then injected every 8 hrs.Activation of TRPV4R by hypotonicity or 4α-PDD increased INMDA, which was attenuated by RR.Additionally,antagonism of calcium/cahnodulin-dependent protein kinase Ⅱ (CaMKⅡ) markedly blocked TRPV4R-induced increase in INMDA.Conclusion: Activation of TRPV4R sensitizes the response to NMDAR through CaMKll signaling pathway.Blockage of TRPV4R may exert neuroprotection on cerebral ischemic injury through inhibiting glutamate excitotoxicity.