Fig. 2.

Ethanol (EtOH) prevents reversal of quinpirole (Q) inhibition induced by phorbol 12-myristate 13-acetate (PMA). (A–C) Mean ratemeter graphs of the effects of a 40-minute Q application under different conditions on 3 different pDAergic ventral tegmental area neurons. Vertical bars indicate the firing rate over 5-second intervals. Horizontal bars indicate the duration of drug application (concentrations indicated above bar). (A) Application of Q (35 nM) produced >50% inhibition and was applied for a total of 40 minutes. No reduction in the inhibitory effect of Q was observed over the 40-minute time period. (B) Application of Q (75 nM), in a recording in which PMA (1 μM) was in the pipette, produced >50% inhibition, and was applied for a total of 40 minutes. Substantial reduction in Q-induced inhibition was observed during the 40-minute application period. (C) Application of Q (15 nM), in a recording in which PMA (1 μM) was in the pipette and 80 mM EtOH was in the superfusate, produced >50% inhibition and was applied for a total of 40 minutes. No obvious reduction in Q-induced inhibition was observed during the 40-minute application period. (D) Pooled time course graph for the cells tested with Q with normal saline in the pipette (▪, [Q] = 35.8 ± 3.0 nM, n = 6), with 1 μM PMA in the pipette (▼, [Q] = 50.0 ± 15.9 nM, n = 5), and in the presence of 80 mM EtOH with 1 μM PMA in the pipette (•, [Q] = 38.3 ± 6.7 nM, n = 6). Time indicated on the abscissa reflects time relative to the initiation of Q administration.