The marginal cell of the stria vascularis is associated with the production of the endocochlear potential and potassium-rich endolymph. These facilitate the mechanoelectrical transduction in the sensory hair cells. With the whole-cell recording method we previously had found that an inward current of the marginal cell is blocked by micromolar concentrations of amiloride; the dose is consistent with amiloride- sensitive sodium channels. Immuno-cytochemical study showed that immunoreactivity to antibodies raised against sodium channels from the bovine kidney, is distributed in marginal cells as well as vestibular dark cells. These observations are consistent with the importance of amiloride-sensitive channels in absorbing sodium ions from the endolymph to maintain its unique ionic composition. Preliminary studies of ion channel regulations in these cells were carried out by examining immunocytochemical localization of various GTP-binding proteins.
