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 ami loride-sensitive Na+ channels, a possible pathway for maintaining a lo w Na+ concentration in the endolymph. Whole-cell voltage-clamp experim ent shows that amiloride at 1 mu M concentration reversibly reduces in ward current more than outward current. Immunogold-labeling method sho ws that the luminal and lateral membrane have antigenic sites for thes e antibodies. These observations indicate the presence of amiloride-se nsitive 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 basolater al membrane, amiloride-sensitive Na+ channels may make a relatively sm all contribution to the unusual resting potential.