Nielsen O S
Int J Radiat Biol Relat Stud Phys Chem Med. 1981 Jan;39(1):73-82. doi: 10.1080/09553008114550091.
The lethal response of asynchronous exponentially growing mouse lung (L1A2) cells heated to 42 degrees C under hypoxic conditions was demonstrated in vitro. Acutely hypoxic cells (i.e. heated immediately after 30 min of N2 plus CO2 gassing) and aerobic cells treated under the same extracellular pH were equally sensitive to a single hyperthermic treatment, and incubation under hypoxia for up to 24 hours prior to treatment did not influence cell survival. Similarly, under controlled pH conditions (pH within 7.0 to 7.4) recovery from hyperthermic damage demonstrated by two-dose hyperthermic fractionation (each of 1.5 hours at 42 degrees C) was identical in hypoxic and aerobic cells, and the highest recovery was found at a 10-hour interval. Preheating for 1.5 hours at 42 degrees C induced thermal resistance to a second treatment at 42 degrees C (thermotolerance). At the 10-hour interval the degree of thermotolerance was not influenced by incubation under hypoxic conditions (thermotolerance ratio, TTR equals 4.7 in both aerobic and hypoxic cells). The data indicate that hypoxic conditions do not influence the heat response in L1A2 cells to either a single or a two-dose fractionated hyperthermic treatment in which hypoxia or aerobic conditions were maintained in the interval between the heat treatment.
体外实验证明了在缺氧条件下，异步指数生长的小鼠肺（L1A2）细胞加热至42摄氏度时的致死反应。急性缺氧细胞（即在通入N2加CO2 30分钟后立即加热）和在相同细胞外pH值下处理的需氧细胞对单次热疗同样敏感，并且在处理前缺氧孵育长达24小时并不影响细胞存活。同样，在受控pH条件下（pH在7.0至7.4之间），两剂量热疗分次治疗（每次在42摄氏度下1.5小时）所显示的热损伤恢复情况在缺氧细胞和需氧细胞中是相同的，并且在间隔10小时时恢复程度最高。在42摄氏度下预热1.5小时可诱导对42摄氏度第二次治疗的热耐受性。在间隔10小时时，热耐受程度不受缺氧条件下孵育的影响（需氧细胞和缺氧细胞的热耐受比，TTR均等于4.7）。数据表明，在热疗间隔期间维持缺氧或需氧条件的单次或两剂量分次热疗中，缺氧条件不会影响L1A2细胞的热反应。
