(A) The effect of chronic hypoxia (48 hours at 8% O₂) on the density distribution of erythrocytes in an SAD mouse. This animal is representative of 6 animals. D₅₀ was 1.099 ± 0.002 at baseline and increased after hypoxia to 1.107 ± 0.004 (P < .05, n = 6). (B) The effect of HU treatment on the changes induced by chronic hypoxia in an SAD mouse. This animal is representative of 6 animals. D₅₀ was 1.101 ± 0.002 at baseline, 1.098 ± 0.003 (P < .05, n = 6) after 3 weeks of HU treatment, and 1.101 ± 0.004 (not significantly different [NS] from baseline) after hypoxia. (C) The effect of CLT treatment on the changes induced by chronic hypoxia in an SAD mouse. This is representative of 5 animals. D₅₀ was 1.097 ± 0.001 at baseline, 1.092 ± 0.01 (P < .005, n = 5) after 3 weeks of CLT treatment, and 1.097 ± 0.02 (NS from baseline) after hypoxia. (D) The effect of Mg treatment on the changes induced by chronic hypoxia in an SAD mouse. This is representative of 5 animals. D₅₀ was 1.097 ± 0.001 at baseline, 1.093 ± 0.001 (P < .05, n = 5) after 3 weeks of Mg treatment, and 1.096 ± 0.002 (NS from baseline) after hypoxia. (E) The effect of CLT+Mg treatment on the changes induced by chronic hypoxia in an SAD mouse. This is representative of 6 animals. D₅₀ was 1.102 ± 0.002 at baseline, 1.095 ± 0.002 (P < .005, n = 5) after 3 weeks of CLT+Mg treatment, and 1.096 ± 0.005 (P < .05 from baseline) after hypoxia.