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 of tissues, including a non-selective cation channel in the mammalian outer hair cell (OHC). We have further investigated the effects of 3'-5-dichlorodiphenylamine-2-carboxylic acid (DCDPC) on OHC currents using the whole-cell configuration of the patch clamp technique. Extracellular application of 10 microM DCDPC rapidly and reversibly activated an inward current at hyperpolarized potentials. The DCDPC-activated current appeared in the shorter OHCs from the basal turns of the cochlea. The reversal potential of the inward current was dependent on the external K+ ion concentration. An outwardly rectifying K+ current, found predominantly in OHCs from apical turns, was reversibly inhibited by DCDPC. These results suggest that DCDPC has a significant effect on OHC physiology at all tonotopic locations along the basilar membrane and so may have implications for cochlear function during fenamate intake.
Jagger
D J
DJ
Department of Physiology, University College London, UK.
Ashmore
J F
JF
D000818:Animals; D004159:Diphenylamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects*
D015221:Potassium Channels; C059537:3',5-dichlorodiphenylamine-2-carboxylic acid; D004159:Diphenylamine