[Effect of hypoxia on the relationship of density and maturity of erythrocytes of newborn, young and adult rats].

Adult male, juvenile and pregnant rats were exposed to repeated hypoxia 8 h daily for 3-9 days in a low pressure chamber (altitude of 5000 m, pO2 = 11.3 kPa and 6000 m, respectively, pO2 = 9.89 kPa). The density distribution curves of the red blood cells (RBC) and the incorporation of 59Fe into cells of different density were determined. In the ontogenesis the density of RBC increases (median density on the first day of life 1.100 kg/l; on the 21st day of life 1.102 kg/l, adult rats 1.103 kg/l). The density difference between the 1st and 4th quartile in which 50% of the cells range was 0.010 kg/l for newborn and juvenile animals and 0.004 kg/l for adult ones. Exposure to hypoxia led iN the animals of the investigated age groups to a rise of the proporborns, 0.004 for juveniles, and 0.002 kg/l for adult rats. The cumulative distribution curves of 59Fe incorporation and density of RBC can be described by the equation (formula: see text). The value alpha characterizes the relation between density, on the one hand, and the maturity and age of cells, on the other. For control and hypoxic animals the following values for alpha have been calculated: for newborns 0.515 and 0.520, for juveniles 0.829 and 0.596 (p less than or equal to 0.01), and for adult rats 0.875 and 0.823. Juvenile animals from in regard to density similar heterogenic cells as newborns after hypoxia. It may be that ontogenetically older cell forming sites or clones are reactivated.