The membrane potential of vestibular dark cells is controlled by a large Cl- conductance.
The K+ secretory epithelium of the vestibular labyrinth (dark cells) was impaled with glass microelectrodes in order to test the hypothesis that it contains a large Cl- conductance. In the first series of experiments, the short-circuited epithelium was perfused on both sides by a solution containing 150 mmol/l Cl-. The membrane voltage (PD) was -18 +/- 1 mV (N = 101), showed a Gaussian distribution, and the estimated input resistance of the cell (R 'cell') was 17 +/- 3 M omega. The PD responded to 10(-4) mol/l ouabain with a depolarization, suggesting the presence of a (Na(+) + K+)-ATPase. The PD responses to Cl- steps yielded an apparent transference number tCl = 0.34 +/- 0.03 (N = 65) and those to K+ steps yielded a tK = 0.16 +/- 0.01 (N = 48). In the second series of experiments, cells presumed to be Cl(-)-depleted were impaled in Cl(-)-free solutions. The distribution of the PD was not Gaussian; PDs as negative as -90 mV were observed. Cells with a highly negative PD also had a high R 'cell'. With the addition of Cl- the PD collapsed to -19 +/- 1 mV and R collapsed to 16 +/- 3 M omega (N = 145) which are not significantly different from values obtained in the first series of experiments when cells were impaled in a solution containing 150 mmol/l Cl-. Alternating the bath perfusate between Cl(-)-free and Cl(-)-containing solutions led to large PD transients.(ABSTRACT TRUNCATED AT 250 WORDS)
Wangemann
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Boys Town National Research Hospital, Cell Physiology and Biophysics Laboratory, Omaha, Nebraska 68131.
Marcus
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DC
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism*; D004159:Diphenylamine / Q000031:analogs & derivatives / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology; D004567:Electrodes, Implanted; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005849:Gerbillinae; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D009579:Nitrobenzoates / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D014722:Vestibule, Labyrinth / Q000166:cytology / Q000378:metabolism*
D018118:Chloride Channels; D002712:Chlorides; D004232:Diuretics; D008565:Membrane Proteins; D009579:Nitrobenzoates; D013449:Sulfonamides; C059537:3',5-dichlorodiphenylamine-2-carboxylic acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D010042:Ouabain; D004159:Diphenylamine; C015451:piretanide; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium