Figure 1.

Effects of tyrosine kinase inhibitors on Ca²⁺-dependent dopamine (DA) release from PC12 cells. PC12 cells were incubated for 20 min in the presence (●) or absence (○) of the tyrosine kinase inhibitor genistein (50 μM) (A) or PP2 (20 μM) (B) in low-K⁺ solution. An inactive genistein analogue (genistin, 50 μM) or an inactive PP2 analogue (PP3, 20 μM) was used as a control (■) to estimate the side effects of these inhibitors. After treatment, the cells were washed three times with low-K⁺ solution, then the extracellular buffer was changed four times every 2 min. Dopamine release was evoked with 0.5 μM ionomycin during the period indicated. The amount of dopamine released in the medium was expressed as percentages of the total cellular content. The values are the mean ± SEM from four (A) or six (B) representative experiments.