Hematology and red cell morphology in guinea pigs acclimated to chronic hypoxia during growth

Abstract

1. 1. Weanling male guinea pigs were exposed for up to 14 weeks to an ambient P o 2 of 80 torr. Hematological measurements made on these animals were compared to data for normoxic controls of similar age and body weight. 2. 2. Within 2 weeks of hypoxic exposure, hematocrit was increased by 42% and [Hb] by 41% compared to controls. However, these changes were accompanied by only a 13% increase in the No. RBC's/mm 3 during the same period; mean red cell volume and mean cell hemoglobin content were each increased by 22% compared to controls. Normochromic macrocytes as well as numerous nucleated RBC's were evident in the peripheral smears of the hypoxia acclimated animals. 3. 3. Frequency analysis of RBC diameters showed a single peak at 6.3 μm for all controls. In guinea pigs acclimated to P O 2 = 80 torr, RBC diameters were initially bimodally distributed, with peaks at 6.3 and 7.6 μm, and later were broadly distributed with a mean of 7.0 μm. 4. 4. These findings support the hypothesis that, under severe and chronic erythropoietic stress, normochromic macrocytes appear in the peripheral blood following a skipped terminal mitotic division, during which cytoplasmic volume would normally be reduced.