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.
Iwasa
K H
KH
Laboratory of Cellular Biology, NIDCD, National Institutes of Health, Bethesda, MD 20892.
Mizuta
K
K
Lim
D J
DJ
Benos
D J
DJ
Tachibana
M
M
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003051:Cochlea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004594:Electrophysiology; D006168:Guinea Pigs; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects; D015222:Sodium Channels / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*
D015222:Sodium Channels; D000584:Amiloride