INWARDLY RECTIFYING K- A POSSIBLE CONTRIBUTION TO THE ENDOCOCHLEAR POTENTIAL( CURRENTS IN INTERMEDIATE CELLS IN THE COCHLEA OF GERBILS )

The stria vascularis in the cochlea generates the endocochlear potenti al (EP) and secretes K+-rich endolymph; both are indispensable for nor mal sound transduction by hair cells. K+ conductance in the intermedia te cell, one of the several types of cells constituting the stria vasc ularis, was investigated by the whole-cell patch-clamp technique. Inwa rdly-rectifying K+ (K-ir) currents were the major currents observed. T he currents were inhibited dose-dependently by Ba2+, quinine, verapami l and Cs+, but not by tetraethylammonium (20 mM), 4-aminopyridine (5 m M) or Cd2+ (1 mM). The similarity between the effect of inhibitors on K-ir currents and on the EP (Takeuchi et al., Hearing Res., 101 (1996) 181-185) suggests a direct contribution of the K-ir conductance to th e generation of the EP. (C) 1998 Elsevier Science Ireland Ltd.