Treatment with NS3623, a novel Cl-conductance blocker, ameliorates erythrocyte dehydration in transgenic SAD mice: a possible new therapeutic approach for sickle cell disease.
The dehydration of sickle red blood cells (RBCs) through the Ca-activated K channel depends on the parallel movement of Cl ions. To study whether Cl-conductance block might prevent dehydration of sickle RBCs, a novel Cl-conductance inhibitor (NS3623) was characterized in vitro using RBCs from healthy donors and sickle cell patients and in vivo using normal mice and a transgenic mouse model of sickle cell disease (SAD mice). In vitro, NS3623 reversibly blocked human RBC Cl-conductance (g(Cl)) with an IC(50) value of 210 nmol/L and a maximal block of 95%. In vivo, NS3623 inhibited RBC g(Cl) after oral administration to normal mice (ED(50) = 25 mg/kg). Although g(Cl), at a single dose of 100 mg/kg, was still 70% inhibited 5 hours after dosing, the inhibition disappeared after 24 hours. Repeated administration of 100 mg/kg twice a day for 10 days caused no adverse effects; therefore, this regimen was chosen as the highest dosing for the SAD mice. SAD mice were treated for 3 weeks with 2 daily administrations of 10, 35, and 100 mg/kg NS3623, respectively. The hematocrit increased, and the mean corpuscular hemoglobin concentration decreased in all groups with a concomitant increase in the intracellular cation content. A loss of the densest red cell population was observed in conjunction with a shift from a high proportion of sickled to well-hydrated discoid erythrocytes, with some echinocytes present at the highest dosage. These data indicate feasibility for the potential use of Cl-conductance blockers to treat human sickle cell disease.
August Krogh Institute, University of Copenhagen, and NeuroSearch A/S, Copenhagen, Denmark.
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P
Bennekou
L
L
de Franceschi
O
O
Pedersen
L
L
Lian
T
T
Asakura
G
G
Evans
C
C
Brugnara
P
P
Christophersen
D000755:Anemia, Sickle Cell / Q000097:blood / Q000188:drug therapy* / Q000473:pathology; D000818:Animals; D018118:Chloride Channels / Q000037:antagonists & inhibitors*; D003681:Dehydration / Q000188:drug therapy; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006400:Hematocrit; D006451:Hemoglobin, Sickle / Q000187:drug effects / Q000378:metabolism; D006454:Hemoglobins / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D010108:Oxyhemoglobins / Q000187:drug effects / Q000378:metabolism; D010671:Phenylurea Compounds / Q000494:pharmacology* / Q000627:therapeutic use / Q000633:toxicity; D013777:Tetrazoles / Q000494:pharmacology* / Q000627:therapeutic use / Q000633:toxicity; D013997:Time Factors; D014867:Water / Q000378:metabolism
D018118:Chloride Channels; D006451:Hemoglobin, Sickle; D006454:Hemoglobins; C423868:NS 3623; D010108:Oxyhemoglobins; D010671:Phenylurea Compounds; D013777:Tetrazoles; D014867:Water; C029775:oxyhemoglobin S