4-acetamido-4--isothiocyanatostilbene-2-2--disulfonic-acid and Hemoglobin-SC-Disease

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.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Animals; Biological Transport; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Chlorides; Erythrocytes; Hemoglobin SC Disease; Humans; Methazolamide; Potassium; Rabbits; Sheep