Fig. 1.

Mean ratemeter graphs of the effects of long-duration application of dopamine (DA) in the presence or absence of either G protein-coupled receptor kinase-2 (GRK2) inhibitor or dynamin inhibitor in single neurons. Vertical bars indicate the firing rate over 5-second intervals; the dashed vertical line indicates the end of DA administration for clarity. Horizontal bars indicate the duration of drug application (concentrations indicated above bar). (A) DA alone initially produced a decrease in the firing rate, which subsided over time in the continued presence of DA. (B) in the presence of 300 μM β-ARK1 inhibitor in the recording pipette, DA produced an inhibition in the firing rate, and this inhibition did not reverse with time. (C) in the presence of 800 µM dynasore in the recording pipette, DA produced an inhibition in the firing rate, with no reversal during DA administration. (D) in the presence of 400 μM MitMAB in the recording pipette, DA produced a statistically significant inhibition in the firing rate over the time course of administration, indicating blockade of reversal.