Figure 3.

Combined interaction of drugs and indoxyl sulfate (IS) on OAT1-mediated fluorescein uptake. (A) Schematic representation of the co-incubation of fluorescein with variable concentrations of drugs and fixed concentration of IS (blue line). (B) The drug alone (grey line) shows a concentration-dependent inhibitory effect. Co-incubation with IS (110 µM, blue line) results in a further decrease of fluorescein uptake. All data are expressed as mean ± SD of four independent experiments. Curves were obtained after non-linear regression analysis. The reference value for the drug alone is fluorescein without the drug (100%), while for the co-incubation with IS the reference value is fluorescein in the presence of IS without the drug (44.0 ± 5.4%). Grey regions indicate the therapeutic window of the respective drug.