title: Quantification of ATP-producing and consuming processes of Ehrlich ascites tumour cells.
abstract: ATP production of Ehrlich ascites tumour cells was estimated on the basis of their coupled respiration and lactate formation. ATP-consuming processes were assessed from the effects of selective inhibitors of RNA synthesis, protein synthesis and proteolysis, Na+/K+-ATPase on respiration. The extent of protein synthesis and proteolysis were also determined directly. From these values and those of the inhibition of respiration by selective inhibitors, a P/O ratio of 2.2 was calculated. About 75% of the total ATP consumption could be assigned to specific processes. The major ATP-consuming processes of tumour cells in an amino-acid-enriched medium, in which they are in an approximate steady state, are protein synthesis with about 30% of total ATP consumption, and Na+/K+-ATPase with about 20%, while RNA synthesis, ATP-dependent proteolysis and Ca2+-ATPase contribute about 10% each. In an amino-acid-free glucose medium, protein synthesis is reduced to a third, with a corresponding decrease of respiration, whereas the rate of the other ATP-consuming processes is unchanged.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000096:biosynthesis / Q000378:metabolism*; D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000378:metabolism; D010101:Oxygen Consumption
chemical_list: D007773:Lactates; D009363:Neoplasm Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D005947:Glucose