Figure 1.

Organic anion transporter (OAT) 1-mediated uptake of fluorescein (FL) in the presence of protein-bund uremic toxins (PBUTs). (A) Schematic representation of the experiment. To evaluate the potency of the transporter, fluorescein was incubated with matured ciPTECs. Fluorescein uptake was then quantified and assigned as 100% uptake. Secondly, fluorescein was incubated together with either probenecid, a known inhibitor of OAT1 activity, or individual PBUTs (IS = indoxyl sulfate, KA = kynurenic acid, PCS = p-cresylsulfate) and UTox (a mix of 8 PBUTs at concentrations found in uremic serum). (B) The intracellular accumulation of fluorescein was measured. Data are shown as mean ± SD of four independent experiments, performed in triplicate. p < 0.005 and p < 0.0001 using one-way ANOVA analysis followed by a Tukey’s multiple comparison test.