ESTROGENS, THIOUREA, THIOURACIL, AND THE TOLERANCE OF RATS TO SIMULATED HIGH ALTITUDES (LOW ATMOSPHERIC PRESSURES)12

Abstract

Additional evidence is presented to demonstrate the effectiveness of thiourea and thiouracil in increasing the resistance of rats to lowered barometric pressures. A smaller need for O2, a more efficient use of the available 02 or an altered metabolism making use of an anaerobic source of energy are cited as possible mechanisms, singly or in combinations, to explain this apparent effectiveness. Daily injns. of 0.05 mg. estradiol dipropionate, estradiol benzoate or diethylstilbestrol did not prolong the survival times of rats subjected to reduced barometric pressures nor did they enhance the protective powers of thiourea or thiouracil. These estrogens did not affect thyroid size or O2 consumption but induced adrenal enlargement. The ability of [female][female] to tolerate low pressures better than [male][male] remains unexplained.