Figure 6.

MC-KARs can be activated by endogenous glutamate. A, Representative experiments showing the effect of TBOA (100 μm; left), DHK (100 μm; middle) mice, and DHK in GluK2 KO mice on MC holding current. Recording conditions were as in Figure 1. Activation of KARs was confirmed by application of the AMPAR/KAR antagonist NBQX (25 μm) at the end of the recording. NBQX was not applied in GluK2 KO as no inward current was detected. B, Quantification of the effect of TBOA (left) and DHK (right) on MC holding current. Dots represent the average current of 2 min of recording taken 2 min before DHK/TBOA application (baseline), 2 min before NBQX application (+DHK/TBOA), and 2 min at the end of NBQX application (+NBQX). Connected dots represent the same cell. C, Top, Representative traces showing the NBQX lack of effect on MC holding current in normal (2.5 mm; left) and high (8.5 mm; right) extracellular K⁺. Bottom, Representative traces showing the effect of 100 μm DHK in the presence of high extracellular K⁺ (left) and the same manipulation in the presence of 25 μm NBQX (right). D, Summary bar graph of the experiments shown in A–C. Each circle corresponds to one cell. Data are presented as the mean ± SEM. *p < 0.05; **p < 0.01; n.s., nonsignificant.