Kashiwagura T, Wilson D F, Erecińska M
J Cell Physiol. 1984 Jul;120(1):13-8. doi: 10.1002/jcp.1041200103.
The dependencies of gluconeogenesis and urea synthesis on oxygen concentration were measured in suspensions of isolated rat hepatocytes and compared with the O2 dependence of cellular energy supply (reduction of cytochrome c, respiratory rate, mitochondrial [NAD+]/[NADH], lactate production, and [ATP]/[ADP] [Pi]). As the oxygen concentration was decreased, production of both glucose and urea declined; the changes were observable at 20 microM oxygen and below, with the apparent Km values for both processes of near 5 microM. The similar dependence of gluconeogenesis and urea synthesis on oxygen concentration indicates that the two pathways have equal access to the cellular ATP supply, i.e., there is no evidence that either pathway is preferentially turned off to spare ATP for the other. The cellular energy state had an oxygen dependence similar to that of glucose and urea synthesis. It is suggested that the behavior of gluconeogenesis and urea production is a reflection of homeostatic regulation of cellular metabolism which is designed to respond to changes in [ATP]/[ADP][Pi].
在分离的大鼠肝细胞悬液中测定了糖异生和尿素合成对氧浓度的依赖性，并将其与细胞能量供应的氧依赖性（细胞色素c的还原、呼吸速率、线粒体[NAD⁺]/[NADH]、乳酸生成以及[ATP]/[ADP][Pi]）进行了比较。随着氧浓度降低，葡萄糖和尿素的生成均下降；在20微摩尔氧气及以下时可观察到变化，这两个过程的表观Km值均接近5微摩尔。糖异生和尿素合成对氧浓度的相似依赖性表明，这两条途径对细胞ATP供应的获取是相等的，即没有证据表明任何一条途径会为了给另一条途径节省ATP而被优先关闭。细胞能量状态具有与葡萄糖和尿素合成相似的氧依赖性。有人提出，糖异生和尿素生成的行为反映了细胞代谢的稳态调节，这种调节旨在响应[ATP]/[ADP][Pi]的变化。
