Energy supply of the mitotic cell cycle and the Na+/H+-antiport in ascites tumors.
The activation of Na+ transport is due to the exchange of protons formed via glucose conversion into lactate for Na+, i.e., to the stimulation of the Na+/H+-antiport. Experimental results and theoretical calculations suggest that in glucose-containing medium the Na+ transport increases from 0.75 to 1.78 pmol/hour per cell. The permeability of plasma membranes for K+ increases 2.75 fold, while the passive flux of Na+ diminishes. The intensity of O2 adsorption by ascites tumor cells does not practically depend on the monovalent cation concentration gradient between the cells and the culture medium, whereas the rate of glycolysis decreases simultaneously with the diminution of the concentration gradient. In synchronized cultures at the beginning of the mitotic cycle, the bulk of ATP resynthesized via glycolysis is utilized for the synthesis of biopolymers, whereas that at the end of the S-phase and in the G2-phase is utilized for cation transport across plasma membranes. From 35 to 100% of the whole amount of ATP resynthesized via glycolysis is utilized for transport purposes. It is concluded that the observed increase in the Na+/K+ ratio in ascites tumor cells is connected with their enhanced ability to synthesize lactic acid. Presumably, glycolysis is one of the regulatory mechanisms of intracellular ratios of monovalent cations.
Kazmin
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SD
R. E. Kavetsky Institute for Oncology Problems, Academy of Sciences of the Ukrainian SSR, Kiev.
Danko
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IM
D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D006019:Glycolysis; D007700:Kinetics; D007941:Leukemia P388 / Q000378:metabolism*; D007942:Leukemia, Experimental / Q000378:metabolism*; D008223:Lymphoma / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008938:Mitosis; D008962:Models, Theoretical; D010101:Oxygen Consumption; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D014407:Tumor Cells, Cultured / Q000378:metabolism
D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium; D011188:Potassium