Figure 2.

D-aspartate and NMDA, but not L-aspartate, block kainate-induced current in hippocampal neurons. (a) Superimposed current records to show the actions of D-aspartate (grey trace, 1 mM) and L-aspartate (black trace, 1 mM) on kainate (200 μM, KA)-induced current. Kainate-induced current was partially inhibited by D-aspartate and little inhibition was observed with L-aspartate. MK801 (5 μM) was added in all solutions to block NMDAR-mediated current. (b) Bar graph illustrates the inhibitory action of D-aspartate (D-asp, 1 mM, grey bar), L-aspartate (L-asp, 1 mM, black bar) and NMDA (1 mM, open bars) on kainate (200 μM)-induced current. The antagonist for NMDARs used for each experiment was indicated on the top of each bar. Concentrations of the antagonists used are: MK801, 5 μM; CPP, 50 μM and D-AP5, 100 μM. (c) Bar graph summarizing the blocking action D-aspartate (1 mM, grey bars) and L-aspartate (1 mM, black bars) on kainate (100 μM)-induced current in the presence and/or absence of glycine (Gly, 10 μM) and magnesium (Mg²⁺, 2 mM). Minus represents no added glycine/magnesium.