Figure 3. Chronic NE-induced GRK2 up-regulation is mediated transcriptionally by G_i/o proteins and ERKs.

α₂AR-transfected PC12 cells were treated with 10 μM NE or vehicle (control) for 6 hours in the presence or absence of 5 μg/mL actinomycin-D (Actino + NE), 100 ng/mL pertussis toxin (PTX + NE), 1 μM Src-inhibtor-1 (SI-1 + NE), or 10 μM PD98059 (PD + NE). At the end of the indicated treatment periods, cells were harvested and total RNA was isolated to perform real-time PCR for GRK2 mRNA quantitation (A) or protein extracts were prepared to perform Western blotting for GRK2 protein quantitation (B). B, Representative Western blots for GRK2, including GAPDH as loading control. C, The densitometric quantitation of GRK2 protein induction. *, P < .05 vs all other groups (n = 5 independent experiments/condition).