Effects of Thyroid and Radiation on Sensitivity to Hypoxia, Basal Rate of O2 Consumption and Tolerance to Exercise

Abstract

In thyroid-treated mice increased basal O2 consumption, increased sensitivity to progressive hypoxia, and decreased tolerance to exercise follow the same course of development in time. After irradiation no increase in basal O2 consumption was found, sensitivity to progressive hypoxia was diminished, and after 325r tolerance to exercise was not decreased within the limits of the test. Thyroid admn. superimposed upon radiation resulted in no increase in basal O2 consumption beyond that caused by thyroid alone, resistance to progressive hypoxia was greater than with thyroid alone, and exercise was tolerated almost as well as with thyroid alone. The large number of early failures and deaths of thyroid-treated mice during exercise indicates defective functional capacity of the heart, which may be somewhat more severe in the irradiated group.