Sulfate-chloride exchange transport in a glioma cell line.
Transport of SO4(2-) was studied in the glioma cell line LRM55 to determine whether it is mediated by the Cl-/HCO3- exchanger or the K+/Cl- cotransporter previously described in these cells (Wolpaw, E.W. and Martin, D.L. (1984) Brain Res. 297, 317-327). 35SO4(2-) influx was saturable with SO4(2-). External SO4(2-) stimulated 35SO4(2-) efflux, indicating an exchange mechanism. External Cl- was a competitive inhibitor of 35SO4(2-) influx. Internal Cl- stimulated 35SO4(2-) influx and external Cl- stimulated 35SO4(2-) efflux, indicating that Cl- is an exchange substrate for the SO4(2-) carrier. Also, SO4(2-) flux was sensitive to SITS, DIDS and furosemide. However, saturating external SO4(2-) did not inhibit 36Cl- influx and did not inhibit 36Cl- efflux via the Cl-/HCO3- exchanger. Moreover, K+ did not stimulate 36Cl- efflux via the Cl-/HCO3- exchanger. Moreover, K+ did not stimulate 35SO4(2-) influx as it does Cl- influx. These findings indicate that SO4(2-) transport into these cells is mediated by an exchange carrier distinct from both the Cl-/HCO3- exchanger and the K+/Cl- cotransporter. While Cl- is an alternative substrate for the SO4(2-) porter, this carrier is responsible for only a minor fraction of total Cl- flux in these cells.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism*; D002713:Chlorine; D005910:Glioma / Q000378:metabolism*; D007700:Kinetics; D011188:Potassium / Q000494:pharmacology; D011868:Radioisotopes; D051381:Rats; D011916:Rats, Inbred F344; D013120:Spinal Cord Neoplasms / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*; D013462:Sulfur Radioisotopes
D002712:Chlorides; D011868:Radioisotopes; D013431:Sulfates; D013462:Sulfur Radioisotopes; D002713:Chlorine; D011188:Potassium