Effect of potassium depletion of Hep 2 cells on intracellular pH and on chloride uptake by anion antiport.
The effect of K+ depletion of Hep 2 cells on ion fluxes, internal pH, cell volume, and membrane potential was studied. The cells were depleted of K+ by incubation in K+-free buffer with or without a preceding exposure to hypotonic medium. Efflux of K+ in cells not exposed to hypotonic medium was inhibited by furosemide or by incubation in Na+-free medium, indicating that in this case at least part of the K+ efflux occurs by Na+/K+/Cl- cotransport. After exposure to hypotonic medium, K+ efflux was not inhibited by furosemide, whereas it was partly inhibited by 4,4'-diisothiocyano-2,2'-stilbene-disulfonic acid (DIDS). Exposure to hypotonic medium induced acidification of the cytosol, apparently because of efflux of protons from intracellular acidic vesicles. When isotonicity was restored, a rebound alkalinization of the cytosol was induced, because of activation of the Na+/H+ antiporter. While hypotonic shock and a subsequent incubation in K+-free buffer rapidly depolarized the cells, depolarization occurred much more slowly when the K+ depletion was carried out by incubation in K+-free buffer alone. The cell volume was reduced in both cases. K+ depletion by either method strongly reduced the ability of the cells to accumulate 36Cl- by anion antiport, and K+-depleted cells were unable to increase the rate of 36Cl- uptake in response to alkalinization of the cytosol.
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000838:Anions / Q000378:metabolism*; D001692:Biological Transport; D002277:Carcinoma / Q000378:metabolism; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005665:Furosemide / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007038:Hypotonic Solutions; D007822:Laryngeal Neoplasms / Q000378:metabolism; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism; D011191:Potassium Deficiency / Q000378:metabolism*; D011868:Radioisotopes / Q000378:metabolism
D000838:Anions; D002712:Chlorides; D007038:Hypotonic Solutions; D011868:Radioisotopes; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D005665:Furosemide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium