Rats in hypoxia groups were inhaled with the mixture of nitrogen gas (0.95 volume fraction) and oxygen (0.05 volume fraction) to establish acute hypoxia models, 2 hours every day and normoxia at other points of time that was the same as normal group.

• 缺氧1；3；5；7d组大鼠分别吸入氮气与大气的混合气体(氮气的体积分数为0.；95、氧气为0