Gnaiger E, Kemp R B
Department of Zoology, University of Innsbruck, Austria.
Biochim Biophys Acta. 1990 Apr 26;1016(3):328-32. doi: 10.1016/0005-2728(90)90164-y.
Calorimetric and respirometric studies of cultured cells show that both neoplastic and non-neoplastic cell types maintain an anaerobic contribution to their total heat flux. In many mammalian cells this can be explained quantitatively by lactate production observed under fully aerobic conditions. Uncoupling and enhanced futile substrate cycling increase the ratio of heat flux to oxygen flux, the calorimetric-respirometric (CR) ratio. The interpretation of calorimetric and respirometric measurements requires an energy balance approach in which experimentally measured CR ratios are compared with thermochemically derived oxycaloric equivalents. The oxycaloric equivalent is the enthalpy change per mole of oxygen consumed, and equals -470 kJ/mol O2 in the aerobic catabolism of glucose, assuming that catabolism is 100% dissipative (the net efficiency of metabolic heat transformation is zero). CR ratios more negative than -470 kJ/mol O2 have been reported in well-oxygenated cell cultures and are discussed in terms of integrated aerobic and anaerobic metabolism.
对培养细胞的量热和呼吸测量研究表明，肿瘤细胞和非肿瘤细胞类型对其总热通量都有厌氧贡献。在许多哺乳动物细胞中，这可以通过在完全有氧条件下观察到的乳酸产生进行定量解释。解偶联和增强的无效底物循环增加了热通量与氧通量的比率，即量热-呼吸（CR）比率。量热和呼吸测量的解释需要一种能量平衡方法，即将实验测量的CR比率与热化学推导的氧热当量进行比较。氧热当量是每消耗一摩尔氧气的焓变，假设分解代谢是100%耗散的（代谢热转化的净效率为零），则在葡萄糖的有氧分解代谢中等于-470 kJ/mol O₂。在充分氧合的细胞培养物中，已报道CR比率比-470 kJ/mol O₂更负，并根据整合的有氧和无氧代谢进行了讨论。
