Cryohydrocytosis: increased activity of cation carriers in red cells from a patient with a band 3 mutation

TY - JOUR

T1 - Cryohydrocytosis

T2 - increased activity of cation carriers in red cells from a patient with a band 3 mutation

AU - Bogdanova, Anna

AU - Goede, Jeroen S.

AU - Weiss, Erwin

AU - Bogdanov, Nikolay

AU - Bennekou, Poul

AU - Bernhardt, Ingolf

AU - Lutz, Hans U.

N1 - Keywords: Adult; Anemia, Hemolytic; Anion Exchange Protein 1, Erythrocyte; Cations; Cold Temperature; Erythrocyte Deformability; Erythrocytes; Humans; Ion Transport; Male; Mutation; Potassium; Sodium-Potassium-Chloride Symporters

PY - 2010/2

Y1 - 2010/2

N2 - Background: Cryohydrocytosis is an inherited dominant hemolytic anemia characterized by mutations in a transmembrane segment of the anion exchanger (band 3 protein). Transfection experiments performed in Xenopus oocytes suggested that these mutations may convert the anion exchanger into a non-selective cation channel. The present study was performed to characterize so far unexplored ion transport pathways that may render erythrocytes of a single cryohydrocytosis patient cation-leaky. Design and Methods: Cold-induced changes in cell volume were monitored using ektacytometry and density gradient centrifugation. Kinetics, temperature and inhibitor-dependence of the cation and water movements in the cryohydrocytosis patient's erythrocytes were studied using radioactive tracers and flame photometry. Response of the membrane potential of the patient's erythrocyte membrane to the presence of ionophores and blockers of anion and cation channels was assessed. Results: In the cold, the cryohydrocytosis patient's erythrocytes swelled in KCl-containing, but not in NaCl-containing or KNO3-containing media indicating that volume changes were mediated by an anion-coupled cation transporter. In NaCl-containing medium the net HOE-642-sensitive Na+/K+ exchange prevailed, whereas in KCl-containing medium swelling was mediated by a chloride-dependent K+ uptake. Unidirectional K+ influx measurements showed that the patient's cells have abnormally high activities of the cation-proton exchanger and the K+,Cl- co-transporter, which can account for the observed net movements of cations. Finally, neither chloride nor cation conductance in the patient's erythrocytes differed from that of healthy donors. Conclusions: These results suggest that cross-talk between the mutated band 3 and other transporters might increase the cation permeability in cryohydrocytosis.

AB - Background: Cryohydrocytosis is an inherited dominant hemolytic anemia characterized by mutations in a transmembrane segment of the anion exchanger (band 3 protein). Transfection experiments performed in Xenopus oocytes suggested that these mutations may convert the anion exchanger into a non-selective cation channel. The present study was performed to characterize so far unexplored ion transport pathways that may render erythrocytes of a single cryohydrocytosis patient cation-leaky. Design and Methods: Cold-induced changes in cell volume were monitored using ektacytometry and density gradient centrifugation. Kinetics, temperature and inhibitor-dependence of the cation and water movements in the cryohydrocytosis patient's erythrocytes were studied using radioactive tracers and flame photometry. Response of the membrane potential of the patient's erythrocyte membrane to the presence of ionophores and blockers of anion and cation channels was assessed. Results: In the cold, the cryohydrocytosis patient's erythrocytes swelled in KCl-containing, but not in NaCl-containing or KNO3-containing media indicating that volume changes were mediated by an anion-coupled cation transporter. In NaCl-containing medium the net HOE-642-sensitive Na+/K+ exchange prevailed, whereas in KCl-containing medium swelling was mediated by a chloride-dependent K+ uptake. Unidirectional K+ influx measurements showed that the patient's cells have abnormally high activities of the cation-proton exchanger and the K+,Cl- co-transporter, which can account for the observed net movements of cations. Finally, neither chloride nor cation conductance in the patient's erythrocytes differed from that of healthy donors. Conclusions: These results suggest that cross-talk between the mutated band 3 and other transporters might increase the cation permeability in cryohydrocytosis.

U2 - 10.3324/haematol.2009.010215

DO - 10.3324/haematol.2009.010215

M3 - Journal article

C2 - 20015879

SN - 0390-6078

VL - 95

SP - 189

EP - 198

JO - Haematologica

JF - Haematologica

IS - 2

ER -