Fisher A B, Dodia C
Am J Physiol. 1984 May;246(5 Pt 1):E426-9. doi: 10.1152/ajpendo.1984.246.5.E426.
The effect of exogenous lactate on glycolytic rate was studied with the isolated perfused rat lung. Glucose utilization was estimated from the rate of 3H2O production from [5-3H]glucose, and lactate and pyruvate production was measured by perfusate assay. Glucose utilization was unaffected by addition of 0.5 mM lactate to the perfusate but decreased by 27% with 1 mM lactate. With 2 mM lactate, glucose utilization was decreased by 46% and lactate production decreased 95%. With addition of 0.2 mM pyruvate plus 2 mM lactate, glucose utilization was decreased 63% compared with control. These data indicate that the effect of lactate on glucose utilization was not through change in the cellular redox state. During lung anoxia produced by ventilation with CO, glucose utilization and lactate production were again markedly decreased by addition of lactate (2 mM) to the perfusate. However, addition of pyruvate plus lactate resulted in a markedly stimulated rate of glucose utilization. This result indicates that during anoxia the effect of lactate on glycolysis resulted from alteration of the redox ratio. This study indicates that lactate influences the rate of glycolysis in the normal lung through its utilization as a substrate for mitochondrial metabolism. During anoxia, changes in the lung redox state with lactate are a major determinant of the glycolytic rate.
采用离体灌注大鼠肺研究外源性乳酸对糖酵解速率的影响。通过[5-³H]葡萄糖生成³H₂O的速率估算葡萄糖利用率，通过灌注液检测测定乳酸和丙酮酸的生成量。向灌注液中添加0.5 mM乳酸对葡萄糖利用率无影响，但添加1 mM乳酸时葡萄糖利用率降低27%。添加2 mM乳酸时，葡萄糖利用率降低46%，乳酸生成量降低95%。添加0.2 mM丙酮酸加2 mM乳酸时，与对照组相比葡萄糖利用率降低63%。这些数据表明乳酸对葡萄糖利用的影响并非通过细胞氧化还原状态的改变。在用CO通气导致肺缺氧期间，向灌注液中添加乳酸（2 mM）会再次使葡萄糖利用率和乳酸生成量显著降低。然而，添加丙酮酸加乳酸会使葡萄糖利用率显著提高。该结果表明在缺氧期间，乳酸对糖酵解的影响源于氧化还原比的改变。本研究表明，乳酸通过作为线粒体代谢的底物影响正常肺中的糖酵解速率。在缺氧期间，肺中乳酸引起的氧化还原状态变化是糖酵解速率的主要决定因素。
