mRNA encoding 'ClC-K1, a kidney Cl(-)- channel' is expressed in marginal cells of the stria vascularis of rat cochlea: its possible contribution to Cl(-) currents.

The cochlear stria vascularis is essential for the normal function of hair cells. mRNA encoding the ClC-K1 Cl(-) channel, previously thought to be found only in the kidney, was detected in epithelial marginal cells of the rat stria vascularis by single cell RT-PCR. When Cl(-) currents were recorded from rat marginal cells by the whole-cell patch clamp method, the steady-state currents showed weak outward rectification and an ion selectivity sequence of SCN(-)Br(-)=Cl(-)F(-)NO(3)(-)I(-)gluconate(-). The Cl(-) currents were regulated by extracellular Ca(2+) and pH. These characteristics resemble those reported for the currents recorded from Xenopus oocytes expressing ClC-K1 Cl(-) channels. These data together suggest that ClC-K1 Cl(-) channels may contribute to the whole-cell currents of marginal cells.