Immunohistochemical localization of the epithelial sodium channel in the rat inner ear.
Endolymph in membranous labyrinth is a K+-rich and Na+-poor fluid, and perilymph is conversely Na+-rich and K+-poor. Electrolyte transport between endolymph and perilymph is important for regulation of volume and osmotic pressure of the labyrinth. The epithelial sodium channel (ENaC) is a good candidate protein for Na+ transport in the tight epithelia, which has been well demonstrated in other tissues such as kidney, colon and lung. The purpose of the present study was to investigate the cellular localization of ENaC subunits in the rat inner ear immunohistochemically with the specific polyclonal rabbit antibodies against the rat alpha-, beta- and gamma-ENaC. All three subunits of ENaC were extensively labeled in the cochlea including the stria vascularis, spiral ligament, organ of Corti, spiral limbus, Reissner's membrane and spiral ganglion, and in the vestibule including the sensory epithelia and stroma cells of the macula utriculi, macula sacculi and ampullary crest. In conclusion, our results suggest that functional ENaC in the labyrinth may work in concert with other Na+ and K+ transport molecules to regulate endolymph and to maintain homeostasis in the inner ear.
Zhong
Shi-Xun
SX
Department of Otolaryngology and Head-Neck Surgery, Daping Hospital, Third Military Medical University, 10 Daping Branch Road, Chongqing 400042, PR China. zhongsx@online.cq.cn
Liu
Zhao-Hua
ZH
D000818:Animals; D007758:Ear, Inner / Q000166:cytology / Q000378:metabolism*; D053503:Epithelial Sodium Channels; D007150:Immunohistochemistry; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000378:metabolism*; D014018:Tissue Distribution
D053503:Epithelial Sodium Channels; D015222:Sodium Channels