Inward-rectifier chloride currents in Reissner's membrane epithelial cells.
Sensory transduction in the cochlea depends on regulated ion secretion and absorption. Results of whole-organ experiments suggested that Reissner's membrane may play a role in the control of luminal Cl(-). We tested for the presence of Cl(-) transport pathways in isolated mouse Reissner's membrane using whole-cell patch clamp recording and gene transcript analyses using RT-PCR. The current-voltage (I-V) relationship in the presence of symmetrical NMDG-Cl was strongly inward-rectifying at negative voltages, with a small outward current at positive voltages. The inward-rectifying component of the I-V curve had several properties similar to those of the ClC-2 Cl(-) channel. It was stimulated by extracellular acidity and inhibited by extracellular Cd2+, Zn2+ and intracellular ClC-2 antibody. Channel transcripts expressed include ClC-2, Slc26a7 and ClC-Ka, but not Cftr, ClC-1, ClCa1, ClCa2, ClCa3, ClCa4, Slc26a9, ClC-Kb, Best1, Best2, Best3 or the beta-subunit of ClC-K, barttin. ClC-2 is the only molecularly-identified channel present that is a strong inward rectifier. This study is the first report of conductive Cl(-) transport in epithelial cells of Reissner's membrane and is consistent with an important role in endolymph anion homeostasis.
Kim
Kyunghee X
KX
Cellular Biophysics Laboratory, Kansas State University, Dept. of Anatomy and Physiology, 228 Coles Hall, Manhattan, KS 66506-5802, USA.
Marcus
Daniel C
DC
D000818:Animals; D000090007:CLC-2 Chloride Channels; D002478:Cells, Cultured; D018118:Chloride Channels / Q000235:genetics / Q000502:physiology*; D002712:Chlorides / Q000502:physiology; D003051:Cochlea / Q000166:cytology / Q000502:physiology*; D004710:Endolymph / Q000502:physiology; D004847:Epithelial Cells / Q000502:physiology*; D006309:Hearing / Q000502:physiology*; D017136:Ion Transport; D051379:Mice; D018408:Patch-Clamp Techniques; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels; D002712:Chlorides