Amiloride-sensitive channels in marginal cells in the stria vascularis of the guinea pig cochlea.

We examined marginal cells in stria vascularis for the presence of amiloride-sensitive Na+ channels, a possible pathway for maintaining a low Na+ concentration in the endolymph. Whole-cell voltage-clamp experiment shows that amiloride at 1 microM concentration reversibly reduces inward current more than outward current. Immunogold-labeling method shows that the luminal and lateral membrane have antigenic sites for these antibodies. These observations indicate the presence of amiloride-sensitive channels in the marginal cell. If amiloride-sensitive channels in the luminal membrane are highly selective to Na+, they could be an efficient pathway for Na+ uptake from the endolymph. In the basolateral membrane, amiloride-sensitive Na+ channels may make a relatively small contribution to the unusual resting potential.