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.
Cellular Biophysics Laboratory, Kansas State University, Dept. of Anatomy and Physiology, 228 Coles Hall, Manhattan, KS 66506-5802, USA.
Kyunghee X
KX
Kim
Daniel C
DC
Marcus
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