Specific drug sensitive transport pathways for chloride and potassium ions in steady-state ehrlich mouse ascites tumor cells |
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Authors: | Felice Aull |
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Institution: | Department of Physiology and Biophysics, New York University Medical Center, 550 First Avenue, New York, NY 10016 U.S.A. |
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Abstract: | A major aim of this investigation was to determine whether, in steady-state ascites cells, Cl? transport can be partitioned into a furosemide-sensitive cotransport with K+ and a separate 4,4′-isothiocyanostilbene-2,2′-disulfonic acid (DIDS) sensitive self-exchange. Both Cl? and K+ fluxes were studied. The furosemide- and Cl? sensitive K+ fluxes were equivalent, both in normal ionic media and when the external K+ concentration, K+]o, was varied from 4 to 30 mM. The stoichiometry of the furosemide-sensitive Cl? and K+ fluxes was 2 Cl?: 1 K+ at 0.1 and 0.5 mM drug levels but increased to 3 Cl? : 1 K+ at 1.0 mM furosemide. DIDS at 0.1 mM had no effect on the K+ exchange rate but inhibited Cl? exchange by (S.E.). The effects of DIDS and 0.5 mM furosemide on Cl? transport were additive but 1.0 mM furosemide and DIDS had overlapping inhibitory actions. Thus furosemide acts on components of K+ and Cl? transport which are linked to each other, but the drug also inhibits an additional DIDS-sensitive Cl? pathway, when present at higher concentrations. The dependence of the furosemide-sensitive K+ and Cl? transport on K+]o was also studied; both fluxes fell as the K+]o increased. The latter results recall those in an earlier study by Hempling (Hempling, H.G. (1962) J. Cell. Comp. Physiol. 60, 181–198). |
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Keywords: | Furosemide DIDS (Ascites cells) DIDS 4 4′-isothiocyanostilbene-2 2′-disulfonic acid IBS 1-isothiocyanate-4-benzenesulfonic acid Mops 4-morpholinepropanesulfonic acid SITS 4-acetamido-4-isothiocyanostilbene-2 2′-disulfonic acid |
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