Figure 5.

(A) Accumulation and polyglutamylation of [³H]MTX. 2008 and 2008/MRP3–8 cells were incubated 1 μM [³H]MTX for 4 and 24 h. Black bars represent the total intracellular pool of [³H]MTX and short-chain [³H]MTX-polyglutamates (MTX-Glu_2–3). Hatched bars represent the total intracellular pool of long-chain polyglutamates of [³H]MTX (MTX-Glu_4–6). Results presented are the mean ± SD (for total pool of all [³H]MTX) of three to four independent experiments. (B–D) Export of [¹⁴C]DNP-GS from MDCKII and MDCKII/MRP3–17 cells grown in monolayers. Cells were incubated at room temperature with 1-chloro-2,4-dinitro[¹⁴C]benzene (2 μM) in both the apical and basal compartment. Samples were taken at t = 1, 3, 6, 12, and 20 min and extracted with ethyl acetate. The experiments were done in duplicate. Variation between measurements was in most cases within the size of the symbols. ■ = transport to basal compartment; ♦ = transport to apical compartment. (B) Intracellular [¹⁴C]DNP-GS levels at the end of the experiment (t = 20); (C) DNP-GS efflux from MDCKII cells; (D) DNP-GS efflux from MDCKII/MRP3–17 cells.