4-acetamido-4--isothiocyanatostilbene-2-2--disulfonic-acid and Uremia

We have studied the transport activity of the erythrocyte anion exchanger by measuring the DIDS-sensitive Li+ influx in fresh red blood cells incubated in HCO3- medium. In addition, the amount of erythrocyte band 3 protein was determined by electrophoretic analysis. The study was performed in twenty uraemic patients on chronic haemodialysis (12 males and 8 females, mean age 47.9 years), and in 20 healthy controls (10 males and 10 females, mean age 44.7 years). Mean time on haemodialysis was 63.9 months (range 6-170 months). The DIDS-sensitive Li+ influx was decreased in erythrocytes from uraemic patients as compared to erythrocytes from controls (619.6 +/- 34.1 vs 761.2 +/- 36.6 mumol/l cell x h, P less than 0.01). The content of band 3 protein was decreased in erythrocytes from uraemic patients as compared to erythrocytes from controls (30.01 +/- 0.39 vs 32.12 +/- 0.48%, P less than 0.01). These results indicate that the Cl-/NaCO3- anion exchanger is altered in erythrocytes from uraemic patients in chronic haemodialysis, and suggest that the regulation of ion content may be compromised in the red blood cells of these patients.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Adult; Aged; Anion Exchange Protein 1, Erythrocyte; Bicarbonates; Carrier Proteins; Chloride-Bicarbonate Antiporters; Chlorides; Erythrocytes; Female; Humans; In Vitro Techniques; Ion Exchange; Lithium; Male; Middle Aged; Sodium; Sodium Bicarbonate; Uremia

To evaluate whether adenosine 3',5'-cyclic monophosphate (cAMP) modulates ionic permeabilities of nonpolarized cells, as reported in diverse polarized epithelia, relative ionic permeabilities were determined in human red cell ghosts by means of the potential-sensitive fluorescent probe 3,3'-dipropylthiadicarbocyanine iodide. Relative ionic chloride permeability (PCl/PK), but not PNa/PK, was significantly increased in ghosts prepared from normal red blood cells (RBCs) exposed to cAMP analogues or forskolin, with the latter at a concentration that significantly increased intracellular cAMP concentration. As basal RBC cAMP concentrations of untreated uremic subjects were also increased, relative permeabilities of ghosts and unstimulated RBC cAMP concentrations were compared in normal, uremic, and dialyzed subjects, PCl/PK was significantly increased in uremic compared with normal subjects; PNa/PK was not altered. PCl/PK and RBC cAMP concentrations were indistinguishable in normal and dialyzed subjects. Neither the kinetics nor number of Cl(-)-HCO3- antiporters, assessed with the pH-sensitive probe acridine orange and the disulfonic stilbene 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, respectively, were altered in uremic cells. These studies suggest that cAMP modulates ionic chloride permeability via increased chloride conductance of each Cl(-)-HCO3- antiporter or by activation/opening of new or existing channels in RBC membranes.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Adult; Cell Membrane Permeability; Colforsin; Cyclic AMP; Erythrocyte Membrane; Erythrocytes; Humans; Ions; Kidney Failure, Chronic; Membrane Potentials; Peritoneal Dialysis, Continuous Ambulatory; Potassium Chloride; Reference Values; Uremia