Polyphosphate suppresses the glutamate receptor synaptic response. A, Representative traces illustrating the impact of 20 μm PolyP on the response generated by isolated NMDARs from DGCs from the hippocampus. Top, L-PolyP (L-PP); bottom, S-PolyP (S-PP). B, Summary of the effects depicted in A: first response amplitudes and PPR. C, Representative traces illustrating the impact of 20 μm PolyP on the response generated by isolated AMPARs in DGCs. Top, L-PolyP (L-PP); bottom, S-PolyP (S-PP). D, Statistical summary of the effects of PolyP in C on the first response amplitudes and PPR. Data were normalized to values generated under control; asterisks denote significance of difference from unity. *p < 0.05, **p < 0.01.