Poizat C, Grably S, Cuchet P, Keriel C
Laboratoire de Bioénergétique Fondamentale et Appliquée Université Joseph Fourier, Grenoble, France.
Arch Physiol Biochem. 1996;104(1):71-80. doi: 10.1076/apab.104.1.71.12874.
The purpose of this study is to determine the relationship between cardiac performance and energy production in isolated rat heart when heart function is modified either by calcium concentration or by oxygen partial pressure (PO2), and to evaluate the relative contribution of glycolytic ATP. Hearts are perfused at a constant 10 ml/min flow and submitted to increasing calcium concentration (0.36 to 1.78 mM free calcium) with maximal PO2 or to graded hypoxia (660 to 52 mmHg) with maximal calcium concentration. Cardiac performance, oxygen consumption (VO2), lactate+pyruvate production are measured. To inhibit glycolysis, perfusions are also carried out with deoxyglucose (2-DG). The plotting of mitochondrial ATP production, as calculated from VO2 vs contractility parameters shows a different relationship when we modify the PO2 or the calcium concentration, whereas the relationship is similar for heart rate. When cardiac performance is related to total ATP production, glycolytic ATP being calculated from lactate+pyruvate production, the difference, although decreased, remains. 2-DG impairs heart function, but with 2-DG the relationship between ATP production and heart function becomes unique. In conclusion, there is an evident difference in the dependence of heart contractility on ATP production according to the factor that limits heart function. The contribution of glycolysis to energy production does not explain all of this difference. Furthermore, such a difference does not exist for heart rate. This raises the question of energy compartmentation in myocardial cells.
本研究的目的是确定在离体大鼠心脏中，当心脏功能通过钙浓度或氧分压（PO₂）改变时，心脏功能与能量产生之间的关系，并评估糖酵解产生的三磷酸腺苷（ATP）的相对贡献。心脏以10毫升/分钟的恒定流量灌注，并在最大PO₂条件下接受递增的钙浓度（游离钙浓度从0.36到1.78毫摩尔），或在最大钙浓度条件下接受分级低氧（从660到52毫米汞柱）处理。测量心脏功能、耗氧量（VO₂）、乳酸+丙酮酸生成量。为抑制糖酵解，还使用脱氧葡萄糖（2-DG）进行灌注。根据VO₂计算的线粒体ATP生成量与收缩性参数的绘图显示，当改变PO₂或钙浓度时，关系不同，而心率的关系相似。当心脏功能与总ATP生成相关时，糖酵解ATP由乳酸+丙酮酸生成量计算得出，差异虽有所减小，但仍然存在。2-DG损害心脏功能，但使用2-DG时，ATP生成与心脏功能之间的关系变得单一。总之，根据限制心脏功能的因素，心脏收缩性对ATP生成的依赖性存在明显差异。糖酵解对能量产生的贡献并不能解释所有这些差异。此外，心率不存在这种差异。这就提出了心肌细胞中能量分隔的问题。
