Fig. 5.

GW4064 treatment led to up-regulation of CAT-1 expression in cultured human proximal tubular epithelial cells (HKC-8) and human hepatoma cells (HepG2), and increased cellular uptake of ADMA. HKC-8 or HepG2 cells at 70% confluence were treated with various concentrations of GW4064 or vehicle alone (DMSO). The expression of CAT-1 mRNA (A) and protein (B) was examined at 16 and 24 h after the treatment by real-time RT-PCR and Western blot analysis, respectively. In a separate experiment, cells were similarly treated with GW4064 or DMSO for 18 h. Cells were then treated with ²H₆-ADMA (10 μM) in HEPES-Krebs buffer for 20 min. C, the amounts of ²H₆-ADMA that are taken up by cells were determined by UPLC-MS as described under Materials and Methods. n = 6. NT, no treatment.