Clark J M
J Appl Physiol Respir Environ Exerc Physiol. 1981 May;50(5):1036-44. doi: 10.1152/jappl.1981.50.5.1036.
Groups of 16-52 normal or CO2-adapted rats were exposed top 100% O2 or to O2 with 60 Torr PICO2 (O2-CO2) at pressures of 1.0, 1.5, 2.0, 3.0, and 4.0 ATA. Exposure durations for 50% mortality (LD50) in normal rats at 4.0, 3.0, 2.0, 1.5, and 1.0 ATA O2 were 6.3, 9.3, 17.2, 27.4, and 76.1 h, respectively. Corresponding LD50 values for normal rats exposed to O2-CO2 were 2.0, 2.9, 16.3, 24.8, and 74.8 h. Survival times of CO2-adapted rats exposed to O2 were nearly identical to those of normal rats. LD50 values for CO2-adapted rat exposed to O2-CO2 were 4.1, 7.5, 17.9, 23.6, and 65.4 h, respectively. These data confirm acceleration of O2 intoxication by acute hypercapnia at 4.0 and 3.0 ATA, but they show less prominent effects at 2.0, 1.5, and 1.0 ATA. Hypercapnia adaptation clearly has a protective effect in rats exposed to O2-CO2 at 4.0 and 3.0 ATA. At 2.0, 1.5, and 1.0 ATA, where acute hypercapnia has less effect, the effects of CO2 adaptation are also less prominent. The observed changes in oxygen tolerance can be explained by cerebral vasodilation with increased brain oxygenation in acute hypercapnia and by significant amelioration of this response during chronic hypercapnia.
将16 - 52只正常或适应二氧化碳的大鼠分为若干组，分别在1.0、1.5、2.0、3.0和4.0ATA的压力下暴露于100%氧气或含60Torr二氧化碳分压的氧气（氧气 - 二氧化碳混合气）中。正常大鼠在4.0、3.0、2.0、1.5和1.0ATA氧气环境下的50%致死时间（LD50）分别为6.3、9.3、17.2、27.4和76.1小时。暴露于氧气 - 二氧化碳混合气的正常大鼠的相应LD50值分别为2.0、2.9、16.3、24.8和74.8小时。暴露于氧气中的适应二氧化碳的大鼠的存活时间与正常大鼠几乎相同。暴露于氧气 - 二氧化碳混合气的适应二氧化碳的大鼠的LD50值分别为4.1、7.5、17.9、23.6和65.4小时。这些数据证实了在4.0和3.0ATA时急性高碳酸血症会加速氧气中毒，但在2.0、1.5和1.0ATA时影响不太显著。高碳酸血症适应在4.0和3.0ATA暴露于氧气 - 二氧化碳混合气的大鼠中显然具有保护作用。在2.0、1.5和1.0ATA时，急性高碳酸血症影响较小，二氧化碳适应的效果也不太显著。观察到的氧耐受性变化可以通过急性高碳酸血症时脑血管扩张伴脑氧合增加以及慢性高碳酸血症期间这种反应的显著改善来解释。
