Dopamine receptor agonists and antagonists enhance ATP-activated currents

The effects of dopamine and related compounds on ATP-activated channels were investigated in pheochromocytoma PC12 cells. Dopamine (10 microM) enhanced an inward current activated by 100 microM ATP. A similar enhancement of the ATP-activated current was observed with apomorphine (10 microM), a non-selective dopamine receptor agonist, with (+)-SKF-38393 (10 microM), a selective dopamine D1 receptor agonist, and with (-)-quinpirole (10 microM), a selective dopamine D2 receptor agonist. Moreover, (+)-SCH-23390 (30 microM), a dopamine D1 receptor antagonist, and (-)-sulpiride (30 microM), a dopamine D2 receptor antagonist, also enhanced the ATP-activated current. The results suggest that ATP-activated channels are modulated by dopaminergic mechanisms, and that this modulation cannot be attributed to any single class of dopamine receptors.