Table 2

Blockade of dopamine agonist-mediated potentiation of PMA-stimulated cyclic AMP accumulation

Cell typeDrugCondition/pretreatment
Vehicle+ Spiperone (1 μm)+ Staurosporine (1 μm)+ Pertussis toxin (25 ng/ml)
pmol/well
ACII/D2LControl36.1  ± 4.826.6  ± 8.26.0  ± 1.1** 11.1  ± 5.2**
Dopamine160  ± 25* 15.3  ± 4.53.9  ± 0.86.8  ± 2.4
Quinpirole94.2  ± 13* 19.7  ± 8.53.6  ± 0.67.3  ± 1.9
ACII/D4Control71.3  ± 1136.6  ± 7.14.9  ± 1.4** 24.0  ± 6.7**
Dopamine157  ± 17* 32.7  ± 2.15.1  ± 1.530.6  ± 5.1
Quinpirole139  ± 19* 47.5  ± 8.265.9  ± 1.622.5  ± 5.9

cAMP accumulation was stimulated with 100 nM PMA in the absence (control) and presence of dopamine (1 μm) or quinpirole (1 μm) for 15 min. As indicated, some experiments were carried out in the presence of spiperone (1 μm), staurosporine (1 μm), or after treatment with pertussis toxin (25 ng/ml, 18 hr). Data shown are the mean ± standard error for three or more independent experiments, each conducted with duplicate determinations. * p < 0.01 compared to control cells (Dunnett’s postrepeated measures ANOVA).** p < 0.05 compared to vehicle pretreatment (Student’s t test).