Fig. 2. Inhibitory effect of d,l-AP-4 on Ba2+ currents in mGluR7-transfected cerebellar granule cells. A, Each bar of the histogram represents the mean (± SEM; n = 10 to 18) of fractional reduction of whole-cell Ba2+ current induced byd,l-AP-4 (500 μm) applied alone, in cultured cerebellar granule cells transfected with GFP alone, or cotransfected with GFP + mGluR7. Note that d,l-AP-4 alone inhibited Ba2+ currents only in cotransfected cells.B, Ba2+ currents recorded in a mGluR7-transfected cell, in the absence and presence of 10 μm, 100 μm, 500 μm, or 1 mmd,l-AP-4. Please note the absence of change in activation kinetics in the presence of the agonist.C,D, Activation (C) and inactivation (D) curves of whole-cell Ba2+ currents obtained from two different granule cells, in the absence (control) and presence ofd,l-AP-4 (500 μm). Similar results were obtained from five other cells. E, Time course and concentration-dependent effect of d,l-AP-4 on Ba2+ currents in a mGluR7-transfected cerebellar granule cell. F, Inhibitory effects of ω-Agatoxin-IVA (250 nm), ω-Conotoxin-GVIA (1 μm), and nimodipine (1 μm) on Ba2+ currents obtained in nontransfected cultured cerebellar granule cells or transfected with GFP alone or cotransfected with GFP + mGluR7. Each bar of the histogram represents the mean (± SEM) of at least seven experiments. G, Inhibitory effects of ω-Agatoxin-IVA (250 nm), ω-Conotoxin-GVIA (1 μm), and nimodipine (1 μm) on Ba2+ currents obtained in the presence of d,l-AP-4 (500 μm), in cultured cerebellar granule cells transfected with GFP alone or cotransfected with GFP + mGluR7. Each bar of histogram represents the mean (± SEM) of at least 10 experiments. Note that the percentage of Ba2+ current inhibited by each toxin was similar in control and cotransfected cells, except for ω-Agatoxin-IVA, which was ineffective only in cotransfected cells.