Fig. 5

Bidirectional transport of rhodamine 123 and [³H]-digoxin. Transport and uptake of rhodamine 123 (5 µM) (A and B) and [³H]-digoxin (38.2 nM) (C and D) were assessed in the absence and presence of the P-gp inhibitor zosuquidar (ZSQ) (0.4 µM) over a time course of two hours. The apparent permeabilities were measured from the steady-state fluxes. The uptake of rhodamine 123 (B) and digoxin (D) into cells was probed after the transport study was terminated. Data are shown as mean ± SEM of three individual passages of triplicates (n = 3, N = 3)