Fig. 2.

a, effect of naturally occurring nucleosides and nucleobases (1 mM) on PMAT-mediated [³H]MPP⁺ uptake in MDCK cells. Vector-transfected and PMAT-expressing MDCK cells were incubated with 1 μM [³H]MPP⁺ for 1 min at 37°C in the presence of various nucleosides and nucleobases at 1 mM. Each bar represents the mean ± S.D. (n = 3). *, p < 0.01, significantly different from the control cells with no inhibitor treatment. b, uptake of ³H- or ¹⁴C-labeled nucleosides and nucleobases. Vector-transfected and PMAT-expressing MDCK cells were incubated with 1 μM ³H- or ¹⁴C-labeled nucleosides and nucleobases for 5 min at 37°C in the presence of 0.5 μM NBMPR. Each bar represents the mean ± S.D. (n = 3). *, p < 0.01, significantly different from vector-transfected cells.