Selected pulmonary biochemical and hematological changes produced by prolonged hypoxia in the rat.

Rats were exposed to 12% O2 (1 atm) for 48 hr, then 10% O2 for the duration of the exposures. Significant elevations in enzymes of the glutathione peroxidase system were found in the lungs of rats killed 3.5, 7.5, and 12.5 days of exposure compared to air-breathing controls. Superoxide dismutase was also elevated after hypoxia but nonsignificantly. Animals killed 12.5 days after exposures exhibited 75% (P less than 0.05) more thiobarbituric acid reactive products in their lungs compared to controls. These results along with significant increases of lung lipid peroxidation and in an augmentation of protective antiperoxidative lung defense capabilities. Hypoxia also resulted in enzyme elevations of lung phosphofructokinase and pyruvate kinase, which may indicate an adaptive increase in lung glycolytic capabilities which would be helpful in maintaining lung tissue energy requirements during hypoxia. In addition, it was confirmed that red blood cell count, hemoglobin and hematocrit values increased after prolonged hypoxia. The results of this study might also reflect enzyme elevation/induction due to cellular reparative-proliferative processes following hypoxia.