Ito K, Nioka S, Chance B
Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia 19104.
Adv Exp Med Biol. 1990;277:449-57. doi: 10.1007/978-1-4684-8181-5_50.
The relationship between oxygen concentrations in arteries, cytosol, and mitochondria and high energy phosphate metabolism was studied in perfused rat hearts subjected to low and high workloads during gradual hypoxia. PCr, ATP, and Pi were measured by 31P-NMR. Myoglobin oxygenation and cytochrome aa3 oxidation were measured by the optical method. When influent oxygen tension was decreased gradually, PCr, ATP, %MbO2, %Cytaa3, cardiac work and MvO2 decreased while Pi and Pi/PCr increased in Langendorff and working hearts. These changes occurred, however, at higher PaO2 values in working hearts. The decrease of %MbO2 and %Cytaa3 in Langendorff hearts was parallel where the ratio of %MbO2 / %Cytaa3 was 1:1. However, this ratio was more than 1:1 in working hearts. It had been demonstrated that oxygen gradients change with changing oxygen consumption. Metabolic and heart work changes occurred simultaneously and significant changes occurred at low levels of %MbO2 and %Cytaa3. Some differences were observed between Langendorff and working hearts. Oxidative phosphorylation is a good indicator of ATP synthesis during hypoxia and is regulated by the intracellular oxygen concentration as well as oxygen gradients.
在逐渐缺氧过程中，对处于低负荷和高负荷状态的灌注大鼠心脏，研究了动脉、胞质溶胶和线粒体中的氧浓度与高能磷酸代谢之间的关系。通过31P-NMR测量磷酸肌酸（PCr）、三磷酸腺苷（ATP）和无机磷酸盐（Pi）。通过光学方法测量肌红蛋白氧合和细胞色素aa3氧化。当流入氧张力逐渐降低时，在Langendorff心脏和工作心脏中，PCr、ATP、肌红蛋白氧合百分比（%MbO2）、细胞色素aa3氧化百分比（%Cytaa3）、心脏作功和心肌耗氧量（MvO2）均下降，而Pi和Pi/PCr升高。然而，这些变化在工作心脏中发生时的动脉血氧分压（PaO2）值较高。Langendorff心脏中%MbO2和%Cytaa3的下降是平行的，其中%MbO2/%Cytaa3的比值为1:1。然而，在工作心脏中该比值大于1:1。已经证明，氧梯度随耗氧量的变化而变化。代谢和心脏作功的变化同时发生，并且在%MbO2和%Cytaa3处于低水平时发生显著变化。在Langendorff心脏和工作心脏之间观察到一些差异。氧化磷酸化是缺氧期间ATP合成的良好指标，并且受细胞内氧浓度以及氧梯度的调节。
