A potassium current in guinea-pig outer hair cells activated by ion channel blocker DCDPC

FENAMATE compounds have been reported to inhibit ion channels in a number o f tissues, including a nonselective cation channel in the mammalian outer h air cell (OHC). We have further investigated the effects of 3'-5-dichlorodi phenylamine-2-carboxylic acid (DCDPC) on OHC currents using the whole-cell configuration of the patch clamp technique. Extracellular application of 10 mu M DCDPC rapidly and reversibly activated an inward current at hyperpola rized potentials. The DCDPC-activated current appeared in the shorter OHCs from the basal turns of the cochlea. The reversal potential of the inward c urrent was dependent on the external K+ ion concentration. An outwardly rec tifying K+ current, found predominantly in OHCs from apical turns, was reve rsibly inhibited by DCDPC. These results suggest that DCDPC has a significa nt effect on OHC physiology at all tonotopic locations along the basilar me mbrane and so may have implications for cochlear function during fenamate i ntake. NeuroReport 9: 3887-3891 (C) 1998 Lippincott Williams & Wilkins.