Figure 2.

The adenosine A_2AR agonist CGS (30 nM), but neither the A_2AR antagonist ZM (100 nM) nor the A_2BR antagonist MRS (200 nM), stimulates [³H]DA release from rat striatal synaptosomes. The non-selective adenosine receptor antagonist, caffeine (50 μM), also stimulates [³H]DA release, which may be explained by the observation that the simultaneous blockade of A_2ARs and A_2BRs by ZM and MRS also facilitated [³H]DA release. Data are mean ± SEM of 7–38 experiments performed in duplicate. *P < 0.05, ***P < 0.01 versus 0 FR% (i.e. no change in baseline); n.s., not significant.