Alves P M, McKenna M C, Sonnewald U
Centro de Tecnologia Quimica e Biologica, CTQB, Oeires, Portugal.
Neuroreport. 1995 Nov 13;6(16):2201-4. doi: 10.1097/00001756-199511000-00024.
Astrocytes possess at least two pathways for pyruvate and thus lactate formation involving precursors derived from mitochondria. The present results suggest that malic enzyme is the preferred route for this process. Although overall lactate release appeared to be independent of extracellular lactate concentration, the incorporation of mitochondrial precursors was decreased by starvation, which is known to deplete astrocyte glycogen stores. Using 1-[13C]glucose in the presence of 10 mM lactate led to label incorporation into extracellular lactate which increased from 3.4 +/- 0.4 to 6.5 +/- 0.5% during 4 and 6 h incubation periods, respectively. Lactate production from glycolysis proceeded virtually unaffected by the extracellular lactate concentration. The total amount of lactate in the medium decreased, however, demonstrating that lactate was used as a substrate.
星形胶质细胞至少有两条丙酮酸进而生成乳酸的途径，这涉及到源自线粒体的前体物质。目前的结果表明，苹果酸酶是此过程的首选途径。尽管总体乳酸释放似乎与细胞外乳酸浓度无关，但饥饿会降低线粒体前体物质的掺入，已知饥饿会耗尽星形胶质细胞的糖原储备。在存在10 mM乳酸的情况下使用1-[13C]葡萄糖，会导致标记物掺入细胞外乳酸中，在4小时和6小时的孵育期内，分别从3.4 +/- 0.4%增加到6.5 +/- 0.5%。糖酵解产生的乳酸几乎不受细胞外乳酸浓度的影响。然而，培养基中乳酸的总量减少，表明乳酸被用作底物。
