RED CELLS Formation of Dense Erythrocytes in SAD Mice Exposed to Chronic Hypoxia: Evaluation of Different Therapeutic Regimens and of a Combination of Oral Clotrimazole and Magnesium Therapies

We have examined the effect of hydroxyurea (HU), clotrimazole (CLT), magnesium oxide (Mg), and combined CLT1Mg therapies on the erythrocyte characteristics and their response to chronic hypoxia in a transgenic sickle mouse (SAD) model. SAD mice were treated for 21 days with 1 of the following regimens (administered by gavage): control (n 5 6), HU (200 mg/d; n 5 6), CLT (80 mg/kg/d, n 5 5), Mg (1,000 mg/kg/d, n 5 5), and CLT1Mg (80 and 1,000 mg/kg/d, respectively, n 5 6). Nine normal mice were also treated as controls (n 5 3), HU (n 5 3), and CLT1Mg (n 5 3). Treatment with HU induced a significant increase in mean corpuscular volume and cell K content and a decrease in density in SAD mice. Treatment with the CLT and Mg, either alone or in combination, also increased cell K and reduced density in SAD mice. After 21 days of treatment, the animals were exposed to hypoxia (48 hours at 8% O2) maintaining the same treatment. In the SAD mice, hypoxia induced significant cell dehydration. These hypoxia-induced changes were blunted in either HUor Mg-treated SAD mice and were completely abolished by either CLT or CLT1Mg treatment, suggesting a major role for the Gardos channel in hypoxiainduced dehydration in vivo. r 1999 by The American Society of Hematology.