Figure 6. Dopamine receptors potentiate Gαq-receptor mediated calcium flux through phospholipase C.
Intracellular calcium levels were measured every 2 seconds for 220 seconds and plotted against time. Ca2+ level is shown in percentage normalized to the initial 105 M acetylcholine (ACh) added at 20 seconds. Vehicle (red curve), 105 M dopamine (DA, blue curve), or 105 M DA with 105 M U73122 (PLC inhibitor, green curve) was added at 100 seconds following 105 M ACh at 20 secs, indicated by arrows. As a negative control, vehicle followed by 105 M DA was also measured (black curve). Experiments were performed in parental (A) HEK cells, (B) D1R expressing cells, and (C) D2R expressing cells. Traces are representatives of n = 3 experiments.