title: ICA-17043, a novel Gardos channel blocker, prevents sickled red blood cell dehydration in vitro and in vivo in SAD mice.
abstract: A prominent feature of sickle cell anemia is the presence of dehydrated red blood cells (RBCs) in circulation. Loss of potassium (K(+)), chloride (Cl(-)), and water from RBCs is thought to contribute to the production of these dehydrated cells. One main route of K(+) loss in the RBC is the Gardos channel, a calcium (Ca(2+))-activated K(+) channel. Clotrimazole (CLT), an inhibitor of the Gardos channel, has been shown to reduce RBC dehydration in vitro and in vivo. We have developed a chemically novel compound, ICA-17043, that has greater potency and selectivity than CLT in inhibiting the Gardos channel. ICA-17043 blocked Ca(2+)-induced rubidium flux from human RBCs with an IC(50) value of 11 +/- 2 nM (CLT IC(50) = 100 +/- 12 nM) and inhibited RBC dehydration with an IC(50) of 30 +/- 20 nM. In a transgenic mouse model of sickle cell disease (SAD), treatment with ICA-17043 (10 mg/kg orally, twice a day) for 21 days showed a marked and constant inhibition of the Gardos channel activity (with an average inhibition of 90% +/- 27%, P <.005), an increase in RBC K(+) content (from 392 +/- 19.9 to 479.2 +/- 40 mmol/kg hemoglobin [Hb], P <.005), a significant increase in hematocrit (Hct) (from 0.435 +/- 0.007 to 0.509 +/- 0.022 [43.5% +/- 0.7% to 50.9% +/- 2.2%], P <.005), a decrease in mean corpuscular hemoglobin concentration (MCHC) (from 340 +/- 9.0 to 300 +/- 15 g/L [34.0 +/- 0.9 to 30 +/- 1.5 g/dL], P <.05), and a left-shift in RBC density curves. These data indicate that ICA-17043 is a potent inhibitor of the Gardos channel and ameliorates RBC dehydration in the SAD mouse.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Verona, Verona, Italy. jstocker@icagen.com
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Stocker
authors.forename: Lucia
authors.initials: L
authors.lastname: De Franceschi
authors.forename: Grant A
authors.initials: GA
authors.lastname: McNaughton-Smith
authors.forename: Roberto
authors.initials: R
authors.lastname: Corrocher
authors.forename: Yves
authors.initials: Y
authors.lastname: Beuzard
authors.forename: Carlo
authors.initials: C
authors.lastname: Brugnara
mesh_terms: D000081:Acetamides / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D000755:Anemia, Sickle Cell / Q000097:blood* / Q000188:drug therapy; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003022:Clotrimazole / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D004912:Erythrocytes / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D000860:Hypoxia; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D024681:Potassium Channels, Calcium-Activated / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012413:Rubidium / Q000097:blood; D014320:Triphenylmethyl Compounds / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000081:Acetamides; D002121:Calcium Channel Blockers; D024681:Potassium Channels, Calcium-Activated; D014320:Triphenylmethyl Compounds; D003022:Clotrimazole; D012413:Rubidium; D002118:Calcium; C472774:senicapoc