Fig. 5.

Uric acid uptake in HEK293 cells expressing hOAT1 or cyOAT1 as a function of time and concentration. (A) Uptake of [¹⁴C]-uric acid (20 μM) as a function of time in cells expressing hOAT1 and in empty vector cells. (B) Kinetics of [¹⁴C]-uric acid uptake by hOAT1 and cyOAT1. HEK293 cells overexpressing hOAT1 and cyOAT1 were incubated with [¹⁴C]-uric acid (20 μM) with various concentrations of unlabeled uric acid for 5 minutes. Stock of uric acid was dissolved in 0.1 N NaOH and added to obtain designed concentrations in HBSS buffer plus 10 mM HEPES to maintain pH 7.4. Each point represents the uptake in OAT1-expressing cells minus that in empty vector cells.