Ion channels and ion transporters play important roles in the inner ear. They are important not only for the function of sensory cells, but in creating the specialized environment for sensory cells to function. The stria vascularis is associated with the production of the endocochlear potential and potassium-rich endolymph. With the whole-cell recording method, we had previously found that an inward current of the marginal cell is blocked by a micromolar concentration of amiloride; the dose is consistent with amiloride-sensitive sodium channels. Immuno-cytochemical studies showed that immunoreactivity to antibodies raised against sodium channels from the bovine kidney is distributed in marginal cells as well as vestibular dark cells. We also localized the sodium-potassium- chloride cotransporter in marginal cells and intermediate cells. These elements could be important for maintaining the endolymph. We are also studying ion pathways in sensory cells. We have previously identified stretch-activated channels in outer hair cells. Our current focus is in examining electric coupling between outer hair cells. The coupling affords a mechanism to enhance the receptor potential in outer hair cells and thereby to affect the movement of the basilar membrane through the voltage-dependent motility of these hair cells.
