Figure 7.

Blocking intracellular Ca²⁺ release from IP₃R store by Heparin or Xestospongic C does not change the D1/D5R-mediated suppression of suprathreshold Ca²⁺ spikes. A, Presence of the selective IP₃R inhibitor Xestospongin C in the recording pipette did not change the suprathreshold evoked Ca²⁺ spiking properties in PFC neurons. B, D1/D5R activation by DHX (10 μm) in the presence of Xestospongin C did not prevent D1/D5R-mediated suppression of the suprathreshold evoked Ca²⁺ spike, suggesting that D1/D5R-mediated suppression of suprathreshold evoked Ca²⁺ spikes does not depend on intracellular Ca²⁺ release from IP₃R stores. C, Time course of the evoked Ca²⁺ spike response to DHX in the presence of Xestospongin C. A and B represent the time point at which representative traces were taken above. D, Histograms of group data showing that D1/D5R activation still suppresses the Ca²⁺ spike in the presence of a nonselective IP₃R inhibitor (heparin) or a specific IP₃R inhibitor (Xestospongin C), thus suggesting that D1/D5R-mediated suppression of suprathreshold evoked Ca²⁺ spikes does not depend on intracellular Ca²⁺ release from IP₃R stores.