Metabolism of ascites tumor cells. I. Rate of glycolysis and competitive utilization of fructose, mannose, and glucose.

The effects of carbohydrates and other chemical agents on the glycolysis of ascites tumors have been under extensive investigation in this laboratory (21). As par t of the program, the three known glycolyzable sugars, D-glucose, D-mannose, and Dfructose, have been studied to help unravel some of the complex factors involved in the regulation of the rate of glycolysis in the intact cells. I t was considered important to determine the influence of concentration of each hexose on the rate of anaerobic glycolysis. I t was also considered relevant to study the glycolyzable sugars in combination to ascertain whether their effects on anaerobic hexose utilization and lactic acid production are competitive or additive. The metabolism of the sugars has been investigated under aerobic conditions also, so that the influence of the intricate interactions of the respiratory and glycolytic enzyme systems could be determined. The rate of anaerobic glucolysis was reported to be dependent on the concentration of glucose below 0.011 M in slices of Flexner-Jobling carcinoma (20, p. 135) and of Jensen rat sarcoma (5). In Ehrlich ascites cells, however, the rate of anaerobic glucolysis was shown by Kun (10) to be the same at concentrations of 0.005 and 0.055 M, whereas the rate of anaerobic fructolysis at the lower concentration was 40 per cent of that at the higher level. Under aerobic conditions, the rate of lactic acid production by TA3 ascites tumor cells was found by Bloch-Frankenthal and Weinhouse (1) to be independent of glucose concentration between 0.0005 and 0.0025 M, while tha t by the Lettr6 strain of the Ehrlich ascites tumor varied with the glucose concentration between 0.0001 and 0.01 M. On the other hand, Ehrlich ascites cells were reported by Kemp and Mendel (9) to have a high rate of glucolysis, presumably under aerobic conditions, a t concentrations as low as 0.0002 M. The rate of anaerobic glucolysis and mannolysis