Caetano N N, Campello A P, Carnieri E G, Kluppel M L, Oliveira M B
Departamento de Bioquímica da Universidade Federal do Paraná, Curitiba, Brasil.
Cell Biochem Funct. 1997 Dec;15(4):259-64. doi: 10.1002/(SICI)1099-0844(199712)15:4<259::AID-CBF749>3.0.CO;2-D.
The effects of methotrexate (MTX) on oxygen uptake by permeabilized HeLa cells were evaluated. MTX did not inhibit state III respiration when the oxidizable substrate was succinate, but when the substrates were 2-oxoglutarate or isocitrate the respiration decreased about 50 per cent at 1.0 mM concentration of the drug. This effect was explained by inhibition of 2-oxoglutarate and isocitrate dehydrogenases by MTX. No effect was observed on succinate dehydrogenase. An evaluation of the effects of MTX on malic enzyme activity as measured by pyruvate plus lactate production in intact cells supplied with malate showed a decrease of about 40 per cent in metabolite production using 0.4 mM MTX. HeLa cell malic enzyme, as observed for other tumour cells, is compartmentalized in mitochondria and cytosol, and is another example of a dehydrogenase inhibited by MTX.
评估了甲氨蝶呤（MTX）对透化HeLa细胞摄氧的影响。当可氧化底物为琥珀酸时，MTX不抑制状态III呼吸，但当底物为2-氧代戊二酸或异柠檬酸时，在1.0 mM药物浓度下呼吸下降约50%。这种效应可解释为MTX对2-氧代戊二酸和异柠檬酸脱氢酶的抑制作用。未观察到对琥珀酸脱氢酶有影响。通过在供应苹果酸的完整细胞中丙酮酸加乳酸的产生来测量MTX对苹果酸酶活性的影响，结果显示使用0.4 mM MTX时代谢产物产生减少约40%。与其他肿瘤细胞一样，HeLa细胞苹果酸酶定位于线粒体和胞质溶胶中，是受MTX抑制的脱氢酶的另一个例子。
