Effects of repeated exposure to hypoxia on hypoxia tolerance in mice / 中国病理生理杂志

ABSTRACT

The hypoxia tolerance of mice was significantly increased by repetitive action of auto-hypoxia. The tolerance duration of the 2nd, 3rd, 4th and 5th run was 1.8 2.5 3.0 and 3.6 times longer than that of the Ist one. The survival time of mice that had been exposed to hypoxia repeatedly for four runs was 10 times longer than that of the control animals when both of them were placed in the same low pressure chamber and was 4 times longer while KCN was administrated. The survival time under low oxygen pressure in mice injected with brain extract of resistant mice was 1.8 and 2.1 times longer than that of the saline-injected or normal mice's brain extract-injected animals respectively. These results indicate that some plastic or adaptic changes might occur in the tissue cells particularly in the brain cells during acute and repeated hypoxia. They lead the animals' hypoxia tolerance to a very high level. Water soluble antihypoxic or hypoxia-resistant elements might exist in the brain of hypoxia resistant animals, which were extractable, transferable, and permeable to the blood brain barrier.