中文摘要：

[目的]探讨出生前低氧预处理是否降低由严重低氧所致新生鼠死亡率。[方法]将孕鼠分为4组。长时间轻度低氧预处理组（PP1组）：孕19d大鼠交替吸入15％氧气和空气各10min为1次循环，每天连续6次循环，处理4d,短时间轻度低氧预处理组（PP2组）．孕21d大鼠交替吸入15％氧气和空气，方法同前，2d；长时间中度低氧预处理组（PB组）：孕19d大鼠交替吸入100k氧气和空气，方法同前，4d；对照组（C组）：方法同前，均吸入空气。预处理后让孕鼠自然分娩。将出生后18-24h的新生鼠每组各取40只暴露于严重低氧环境（5％氧气），以对照组新生鼠50％死亡为实验终点，计算各组叹气样呼吸发生率及其他各组新生鼠死亡率。[结果]C组新生鼠吸入5％氧气约105min时有50％死亡、70％出现叹气样呼吸；与C组比较，PP1组死亡率和叹气样呼吸发生率分别降低20％和25％（P〈0．05），PP2组无明显交化（P〉0．05），PP3组分别升高35％和25％（P〈0．05）。[结论]合适的出生前低氧预处理可以降低严重低氧引起的新生鼠死亡率。

英文摘要：

[Objective] To explore whether prenatal preconditioning （PP） with hypoxia would reduce the death of new born rats induced by severe hypoxia. [Methods] These pregnant rats were divided into 4 groups, long time mild hypoxia pretreatment group （PP1 group ） ： Pregnant rats with 19 days ahemately breathed 15% O2 and air for one circulation, and these rats were circulated 6 times for a day, continuously conducted for 4 days. Short-time mild hypoxia pretreatment （PP2 group） ： pregnant rats with 21 days alternately breathed 15% O2 and air, other treatment was the same as before, and continuously conducted for 2 days; long time moderate hypoxia pretreatment group （PP3 group）： Pregnant rats with 19 days alternately breathed 10% O2 and air, other treatment was the same as before, and continuously conducted for 4 days. Control group （C group） ： treatment for control group was the same as before, all of these rats breathed air. After pretreatment for these rats, all of them were natural delivery. For each group, 40 rats after being born at the time of 18 to 24 hours were exposed to serious hypoxia environment （ were collected without PP （C group）, PP with 15% O2 for 4 days （PP1 group）, for 2 days （PP2 group）, and with 10% O2 for 4 days （PP3 group）. Hypexic PP was composed of constant six episodes of intermittent hypoxia （5% O2）. The experiment terminal point was defined as the mortality of control group with 50%. The incidence of gasping breathe in all groups and the mortality in the other three groups were calculated. [Results] Among the control group, 50% of these rats dead when they breathed 5% O2 for 105 minutes, 70% of them showed gasping breathe; When compared with control group, the mortality of rats in PP1 group and incidence of gasping breathe decreased by 20% and 25%, respectively （P 〈 0.05）, in PP3 group increased by 35% and 25%, respectively （P〈 0.05）, and no significantly change for PP2 group （P〉 0.05）. [Conclusion] Appropriately prenatal precond