Figure 2.

Effect of telaprevir on the intravesicular transport of estrone 3-sulfate (E1S) and MTX by BCRP. A. The ability to transport E1S at telaprevir-absent or -present conditions was determined by measuring the radioactivity of [³H]-E1S taken up in membrane vesicles. A similar experiment was done for MTX. B. Analyses of Lineweaver–Burk plots of inhibition of E1S and MTX uptake by BCRP. E1S concentration was 50 nmol/L (A) and 50, 100, and 200 nmol/L (B), and of telaprevir was 0, 1, 10, and 100 μmol/L (A) and 50 μmol/L (B), respectively. MTX concentration was 100 nmol/L (A), and 100, 200 and 400 nmol/L (B). Membrane vesicles of K562/BCRP cells were used. The procedures were almost identical to those shown in Figure 1.