O2 transport in hypoxic albino rats of first and second generation

The generations of rats raised in normobaric hypoxia (10% O2 in N2) were observed for changes in their oxygen-hemoglobin affinity, hemoglobin content (Hb) blood O2 capacity and pO2-O2 content curves: the first generation (H1) and the second generation (H2). H1 rats possessed a lower O2-Hb affinity while H2 rats had a higher O2-Hb affinity than normoxic control rats. Hb was greater in both hypoxic groups, however, H2 rats showed a Hb lower than that of H1 rats. Both hypoxic groups showed a leftward shift of the pO2-O2 content curve. In pO2 range between 25 and 50 mmHg, H2 rats showed a shift greater than H1 rats. So in hypoxic conditions the H1 rat's ability to supply enough O2 to the tissues is smaller than that of H2 rats. In the rat's adaptation to hypoxia the Hb increase plays only a minor role while O2-Hb affinity increase constitutes a physiologically meaningful adaptation.