FIGURE 12.

Effect of the voltage step on the β₁-adrenergic receptor-dependent inward current in layer V mPFC pyramidal neurons. (A) Inward current evoked by bath application of dobutamine alone (DOB, 100 μM, a). At the peak of the inward current, the recording was interrupted, and a 100-ms depolarizing voltage step from the holding potential to +80 mV was applied. Following the voltage step, the inward current was reduced (b). At 20 min after termination of dobutamine application, when the recorded holding current returned to its resting control level, a current was injected from the pipette to obtain the maximum inward current level similar to that during the application of dobutamine. At this current level, a 100-ms depolarizing voltage step from the holding potential to +80 mV was applied again. Following the voltage step, the inward current was reduced (c). In (d), the overlapped current recordings from (b,c) are shown. The amplitude of the current reduction in the presence (x) and absence (y) of dobutamine is indicated. (B) Amplitude of the inward current reduction after the voltage step during dobutamine application [DOB (+)] and in the absence of dobutamine [DOB (–)] in the extracellular solution; ^∗∗∗p < 0.001.