Effect of Known Inhibitors of Ion Transport on Pendrin (SLC26A4) Activity in a Human Kidney Cell Line.

Pendrin is a Cl-/I-/HCO3- exchanger playing a fundamental role in controlling blood pressure and airway function, therefore representing an attractive target for the treatment of hypertensive states and respiratory distresses. A review of the literature regarding the ability of some compounds (namely several known inhibitors of ion transport) to block pendrin activity revealed discordant findings. These incongruous findings may be due, in part, to the concentration of compound and/or the nature of the model system used in the study. Pendrin activity was evaluated by measuring pendrin-dependent iodide influx following overexpression of the transporter in a human kidney cell line, in the presence of selected test compounds or the respective vehicles. Pendrin activity was significantly hampered by 0.1 mM 5-nitro-2-[(3-phenylpropyl)amino]benzoic acid (NPPB), niflumic acid and tenidap, but was resistant to 0.1 mM 4, 4'-diisothiocyano-2, 2'-stilbene-disulfonic acid (DIDS), furosemide and probenecid. The results of the present study indicate that clinically effective non-steroidal anti-inflammatory drugs (niflumic acid and tenidap) directly inhibit pendrin activity.