HY POXIA AND I TS INFLUEN CES ON THE CARDIOVASCULAR AND RESPIRATORY SYSTEMS OF SPONTANEOUSLY BREATHING CATS

Effects of acute systemic hypoxia on the cardiovascular system (CYS) and respiration of spontaneously breathing cats were studied in two conditions. 1): Hypoxic air (6-8% 02 in N2) was given to the animal to induce systemic hypoxia for 20 minutes. Hyperventilation at this condition lowered arterial C02 tension (PaC02 hypocapnia). 2): In the second run, induction of hypocapnia was prevented by adding 3-5% C02 to hypoxic air. Comparison of the results of this study indicated that hypoxia, independent of the presence of hypocapnia, caused a significant increase in respiratory rate, aortic flow and arterial blood pressure. However, in the presence of hypocapnia, the increased respiratory rate was 10% less and a general arterial vasconstriction was observed.