Role of chloride in potassium transport through a K-Cl cotransport system in human red blood cells.
In this paper, we report experiments demonstrating the coupling of Cl and K movements in a volume-dependent K-Cl cotransport system in human red blood cells. We show that an outwardly directed Cl gradient can promote net K efflux against an inwardly directed K gradient at constant membrane potential. Red blood cell membrane potential was kept constant by using anions that are not transported through the K-Cl cotransport system but that are more permeable than Cl (NO3 and SCN). Under these conditions, when the activities of band 3 (capnophorin)-mediated anion exchange and of the carbonic anhydrase have been inhibited, it is possible to maintain a Cl gradient at constant membrane potential. Similar data were obtained in human red blood cells (least dense fraction from normal subjects and whole blood from patients with homozygous hemoglobin S disease), in rabbit red blood cells, and in low-K sheep red blood cells. These data confirm that the volume-dependent Cl-dependent K movement in these cells operates through coupled K-Cl cotransport.
Brugnara
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Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
Van Ha
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Tosteson
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D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006450:Hemoglobin SC Disease / Q000097:blood; D006801:Humans; D008704:Methazolamide / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012756:Sheep
D002712:Chlorides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium; D008704:Methazolamide