title: Stretch-activated nonselective cation, Cl- and K+ channels in apical membrane of epithelial cells of Reissner's membrane.
abstract: Ion channels on the apical membrane of epithelial cells (the surface facing the endolymph) of acutely isolated Reissner's membrane from guinea-pig cochlea were investigated by using patch-clamp technique in cell-attached and inside-out configurations. Three types of ion channel were identified: namely, a stretch-activated nonselective cation, a chloride and a potassium channel. When the pipette was filled with high-K+ endolymph-like solution, the most significant channel activity was nonselective cation channels (85/110, 77% patches). The current versus voltage relationship was linear with a unitary conductance of 22.1 +/- 0.4 pS and reversal potential (Vr) of 2.3 +/- 0.8 mV (n = 18). The channel exhibited a lower conductance (14.0 +/- 0.6 pS, n = 8) to Ca2+. The open probability was low (NPo approximately 0.1) in cell-attached configuration under +60 mV pipette potential and increased when the membrane was stretched with negative pressure. The channel was blocked by 10 microM extracellular Gd3+. The two other types of channels were a small voltage-sensitive Cl- channel (6.0 +/- 0.3 pS; 91/99, 92% patches) and a K+ channel (approximately 30 pS; 29/191, 15% patches). These channels might play roles in the regulation of cell volume, in balancing the hydrostatic pressure across Reissner's membrane and in maintaining the electrochemical composition of endolymph.
authors.affiliation: Department of Otolaryngology, National Taiwan University Hospital, Taipei. yth@ntumcl.mc.ntu.edu.tw
authors.forename: T H
authors.initials: TH
authors.lastname: Yeh
authors.forename: M C
authors.initials: MC
authors.lastname: Tsai
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: M M
authors.initials: MM
authors.lastname: Hsu
authors.forename: P
authors.initials: P
authors.lastname: Tran Ba Huy
mesh_terms: D000818:Animals; D018118:Chloride Channels / Q000378:metabolism*; D003053:Cochlear Duct / Q000378:metabolism* / Q000648:ultrastructure; D004710:Endolymph / Q000378:metabolism / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism / Q000648:ultrastructure; D006168:Guinea Pigs; D007473:Ion Channels / Q000378:metabolism*; D008854:Microscopy, Electron; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D011312:Pressure; D012984:Software
chemical_list: D018118:Chloride Channels; D007473:Ion Channels; D015221:Potassium Channels