SLC23A3 is a renal hypoxanthine transporter.

LLC-PK1 renal cells show Na + -dependent and Na + -independent hypoxanthine uptake. While the latter is inhibited by adenine, neither are inhibited by xanthine. In rats, intestinal Na + -dependent hypoxanthine transporter Slc23a4 is not expressed in the kidney, and its action is inhibited by xanthine. This study aimed to clone Slc23a4 -paralog SLC23A3 from the human kidney and investigate its hypoxanthine transport activity. We observed Na + -dependent 10 nM [ 3 H]-hypoxanthine uptake in SLC23A3 RNA-injected Xenopus oocytes. Moreover, 100 μM xanthine did not inhibit Na + -independent 300 nM [ 3 H]-hypoxanthine uptake, whereas 100 μM adenine did. These results confirm that SLC23A3 is a hypoxanthine transporter in the human kidney.