Inwardly rectifying K⁺ currents in intermediate cells in the cochlea of gerbils: A possible contribution to the endocochlear potential

The stria vascularis in the cochlea generates the endocochlear potential (EP) and secretes K⁺-rich endolymph; both are indispensable for normal sound transduction by hair cells. K⁺ conductance in the intermediate cell, one of the several types of cells constituting the stria vascularis, was investigated by the whole-cell patch-clamp technique. Inwardly-rectifying K⁺ (K(ir)) currents were the major currents observed. The currents were inhibited dose-dependently by Ba²⁺, quinine, verapamil and Cs⁺, but not by tetraethylammonium (20 mM), 4-aminopyridine (5 mM) or Cd²⁺ (1 mM). The similarity between the effect of inhibitors on Kit currents and on the EP (Takeuchi et al., Hearing Res., 101 (1996) 181-185) suggests a direct contribution of the K(ir) conductance to the generation of the EP.