The effects of hyperoxia on oxygen uptake during acute anemia

The effects of normobaric hyperoxia on the oxygen uptake and cardiovascular responses of the whole body and hindlimb during anemia were investigated. Anesthetized, paralyzed dogs were ventilated for 20-min periods with room air (normoxia), 100% O2 (hyperoxia), and returned to room air. Anemia (hematocrit = 15%) was then induced by isovolemic dextran-for-blood exchange and the normoxia, hyperoxia, normoxia sequence was repeated. Whole body and cardiac output rose following anemia, and then fell (p < 0.05) with hyperoxia during anemia. These responses were not abolished by β-blockade with propranolol (1 mg/kg, iv) or bilateral vagotomy. The hindlimb data for blood flow and were similar in direction to those of the whole body but were more variable. Section of the sciatic and femoral nerves did not appear to have significant effect on the limb responses to hyperoxia. The decrease in whole body and hindlimb with hyperoxia during anemia may have resulted from a redistribution of capillary blood flow away from ...