Papa S, Capuano F, Capitanio N, Lorusso M, Galeotti T
Cancer Res. 1983 Feb;43(2):834-8.
The capacity of mitochondria isolated from tumor cells to conserve the transmembrane electrochemical proton gradient set up by respiration has been studied. In a K+ medium, mitochondria from Ehrlich ascites tumor cells exhibit a capacity to conserve aerobic delta microH comparable to that displayed by normal rat liver mitochondria. Mitochondria from Morris hepatoma 3924A show a decreased capacity to store delta microH+, which is principally due to lowering of delta pH. In a Na+ medium, both species of tumor mitochondria show a significant decrease of aerobic delta pH, while delta psi is the same, with respect to rat liver mitochondria. Experiments on passive swelling show that mitochondria from ascites tumor cells have an enhanced permeability to chloride salts of monovalent cations and increased activity of the Na+ (K+)-H+ exchange system of the mitochondrial membrane with respect to normal mitochondria. The enhanced activity of this system in ascites cells is also shown by the characteristics of respiration-linked proton translocation in submitochondrial particles and subsequent anaerobic proton diffusion. It is concluded that the decreased capacity of mitochondria from tumor cells to conserve aerobic delta pH is due to enhanced cyclic flow of Na+ across the membrane.
对从肿瘤细胞中分离出的线粒体维持呼吸作用所建立的跨膜电化学质子梯度的能力进行了研究。在钾离子培养基中，艾氏腹水瘤细胞的线粒体维持需氧质子动力势差的能力与正常大鼠肝脏线粒体相当。莫里斯肝癌3924A的线粒体储存质子动力势差的能力下降，这主要是由于pH值差降低所致。在钠离子培养基中，相对于大鼠肝脏线粒体，两种肿瘤线粒体的需氧pH值差均显著降低，而膜电位相同。被动肿胀实验表明，腹水瘤细胞的线粒体对单价阳离子的氯化物盐的通透性增强，且线粒体膜的钠（钾）-氢交换系统的活性相对于正常线粒体有所增加。线粒体亚基颗粒中呼吸相关质子转运以及随后的厌氧质子扩散的特性也表明，腹水细胞中该系统的活性增强。得出的结论是，肿瘤细胞线粒体维持需氧pH值差的能力下降是由于钠离子跨膜循环流量增加所致。
