[Development of super-resistance to hypoxic hypoxia during adaptation to short-term stress]

Adaptation to intermittent short-term immobilization stress exposure increases the resistance of rats to hypoxic hypoxia. This was evidenced by the fact that in acute experiments in respiration with gas-mixture containing 6% of oxygen, the mortality of control rats was 65% compared with 10% of that of adapted rats. It has been estimated that this protective cross-effect of adaptation to stress is due to more stable and efficient mobilization of external respiration in adapted animals, and to a greater extent, to the fact that adapted rats tissues have gained a capacity of extracting more oxygen from hypoxemic blood compared to control animals. The role of previously stated phenomenon of adaptive stabilization of structures in superresistance to hypoxic hypoxia is discussed.