Figure 11. Dopamine-receptor-induced inhibition of IPSCs is mediated by PKA inhibition. A, B, Effects of tamoxifen (50 μm; A) and chelerythrine (5 μm; B), both of which are PKC inhibitors, on DA-receptor-induced inhibition of IPSCs in D2KO mice. Tamoxifen was included in a patch pipette, and chelerythrine was applied in bath solution. The filled bar indicates DA (30 μm) application in A, B, E, and F. C, Normalized IPSC amplitudes are averaged to plot the control (filled circles; n = 4) and the effects of SQ22,536 (100 μm; open circles; n = 6) for the period indicated by the open bar. D, Normalized IPSC amplitudes are plotted for the control (open circles; n = 5), Sp-cAMPS (filled circles; n = 5), and Rp-cAMPS (filled inverted triangles; n = 3) immediately after membrane rupture. Sp-cAMPS and Rp-cAMPS, an activator and an inhibitor of cAMP, respectively, were included in patch pipettes. E, Effect of the PKA inhibitor SQ22,536 (100 μm) on the amplitude of IPSCs and occlusion of DA receptor-induced inhibition. SQ22,536 was applied as a bath solution. F, Effect of Rp-cAMPS (1 mm), a PKA inhibitor, on DA-receptor-induced inhibition. Rp-cAMPS was included in patch pipettes. G, Summary of the percentage of inhibition of IPSC by DA in the absence (n = 5) or presence of tamoxifen (n = 6), chelerythrine (n = 3), Rp-cAMPS (n = 4), and SQ22,536 (n = 4). The numbers of experiments are shown in parentheses. *p < 0.05; **p < 0.01; unpaired Student's t test.