A novel, volume-correlated Cl- conductance in marginal cells dissociated from the stria vascularis of gerbils.
Using the whole-cell patch-clamp technique, we examined Cl-selective currents manifested by strial marginal cells isolated from the inner ear of gerbils. A large Cl-selective conductance of approximately 18 nS/pF was found from nonswollen cells in isotonic buffer containing 150 mM Cl-. Under a quasi-symmetrical Cl- condition, the "instantaneous' current-voltage relation was close to linear, while the current-voltage relation obtained at the end of command pulses of duration 400 msec showed weak outward rectification. The permeability sequence for anionic currents was as SCN- > Br- approximately = Cl- > F- > NO3- approximately = I- > gluconate-, corresponding to Eisenmann's sequence V. When whole-cell voltage clamped in isotonic bathing solutions, the cells exhibited volume changes that were accounted for by the Cl- currents driven by the imposed electrochemical potential gradients. The volume change was elicited by lowered extracellular Cl- concentration, anion substitution and altered holding potentials. The Cl- conductance varied in parallel with cell volume when challenged by bath anisotonicity. The whole-cell Cl- current was only partially blocked by both 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB, 0.5 mM) and diphenylamine-2-carboxylic acid (DPC, 1.0 mM), but 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid (SITS, 0.5 mM) was without effect. The properties of the present whole-cell Cl- current resembled those of the single Cl- channel previously found in the basolateral membrane of the marginal cell (Takeuchi et al., Hearing Res. 83:89-100, 1995), suggesting that the volume-correlated Cl- conductance could be ascribed predominantly to the basolateral membrane. This Cl- conductance may function not only in cell volume regulation but also for the transport of Cl- and the setting of membrane potential in marginal cells under physiological conditions.
Takeuchi
S
S
Department of Physiology, Kochi Medical School, Nankoku, Japan.
Irimajiri
A
A
D000818:Animals; D000838:Anions / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D048429:Cell Size; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism*; D004553:Electric Conductivity; D004558:Electric Stimulation; D004710:Endolymph / Q000378:metabolism; D005849:Gerbillinae; D066298:In Vitro Techniques; D017136:Ion Transport; D008564:Membrane Potentials; D018715:Microscopy, Video; D009579:Nitrobenzoates / Q000494:pharmacology; D009997:Osmotic Pressure; D012996:Solutions; D013316:Stria Vascularis / Q000166:cytology* / Q000378:metabolism* / Q000502:physiology; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D000838:Anions; D018118:Chloride Channels; D002712:Chlorides; D009579:Nitrobenzoates; D012996:Solutions; D062367:ortho-Aminobenzoates; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; C001209:fenamic acid