Lack of aquaporin-4 water transport inhibition by antiepileptics and arylsulfonamides

Inhibitors of brain glial water channel aquaporin-4 (AQP4) are of potential clinical utility, as they are predicted to modulate brain edema, neuroexcitation and glial scarring. Recently, Huber et al. (Bioorg. Med. Chem.2007, 17, 1270–1273; in press) reported that a series of arylsulfonamides, antiepileptics, and related small molecules strongly inhibited AQP4 water transport with IC50s down to 1 μM. We retested the compounds with greatest reported potencies, including acetylsulfanilamide, acetazolamide, 6-ethoxy-benzothiazole-2-sulfonamide, topiramate, zonisamide, phenytoin, lamotrigine, and sumatriptan, in AQP4-transfected mammalian cells and primary cultures of brain glial cells, using several sensitive assays of osmotic water permeability. Contrary to the findings of Huber et al., in our studies we found no significant inhibition of AQP4 water permeability by any of the compounds at concentrations up to 100 μM.

Several antiepileptics, arylsulfonamides, and related small molecules were tested for their ability to inhibit brain water channel AQP4. Multiple functional assays showed no inhibition by these compounds.Figure optionsDownload as PowerPoint slide