Gacad G, Massaro D
J Clin Invest. 1973 Mar;52(3):559-65. doi: 10.1172/JCI107216.
We studied the time-course of the influence of in vivo hyperoxia on lung mechanics and on protein synthesis. After 24 h of exposure to greater than 98% O2 at 1 atm there were no alterations in descending pressure-volume curves (air or saline) of lungs excised from O2-exposed rats compared to control rats. After 48 h of hyperoxia there was a decrease in lung compliance. To study protein synthesis, as indicated by L-[U-(24)C] leucine incorporation into protein, lung slices were incubated with L-[U-(14)C]leucine and surface-active material then obtained by ultracentrifugation of lung homogenates. We measured radioactivity in total protein and in protein in the surface-active fraction. There were no alterations in incorporation after 12 h of hypertoxia. After 24 h of hyperoxia there were significant decreases (P<0.05) in L-[U-(14)C]leucine incorporation into total protein and into protein of the surface-active fraction. After 48 h of hyperoxia incorporation into protein of the surface-active fraction was decreased to a greater extent than incorporation into total protein, 63+/-4% and 75+/-5%, respectively, (P<0.025). These studies show that hyperoxia produces a major decrease in protein synthesis, including synthesis of protein in a surface-active fraction, before the onset of any detectable changes in the static compliance of excised lungs.
我们研究了体内高氧对肺力学和蛋白质合成的影响的时间进程。在1个大气压下暴露于大于98%的氧气24小时后，与对照大鼠相比，从暴露于氧气的大鼠切除的肺的降压力-容积曲线（空气或盐水）没有改变。高氧48小时后，肺顺应性降低。为了研究蛋白质合成，通过将L-[U-(24)C]亮氨酸掺入蛋白质来指示，将肺切片与L-[U-(14)C]亮氨酸一起孵育，然后通过肺匀浆的超速离心获得表面活性物质。我们测量了总蛋白和表面活性部分蛋白中的放射性。高氧12小时后掺入没有改变。高氧24小时后，L-[U-(14)C]亮氨酸掺入总蛋白和表面活性部分蛋白的量显著降低（P<0.05）。高氧48小时后，表面活性部分蛋白的掺入量比总蛋白的掺入量下降幅度更大，分别为63±4%和75±5%（P<0.025）。这些研究表明，在切除肺的静态顺应性出现任何可检测到的变化之前，高氧会导致蛋白质合成大幅下降，包括表面活性部分蛋白质的合成。
