Relationship between oxygen and glucose consumption by transplanted tumors in vivo.

The in vivo consumption of oxygen and glucose was studied in relation to growth in Walker Carcinoma 256, Hepatoma 5123, and Fibrosarcoma 4956 transplanted in rats. Glucose not elim inated as lactate or carbon dioxide in the efferent blood was pre sumed to be retained by the tumor. The retention was so high that growth alone could not account for it. As an alternative, the elimination of glucose by the tumors in some unknown manner is suggested. The weight-doubling times of the tumors were independent of oxygen consumption and lactate production. The tumors needed oxygen to survive; there was no indication, how ever, that in vivo tumor metabolism shifted from respiration to glycolysis when the supply of oxygen was deficient. The opposite was found to be true: glucose consumption and lactate elimina tion were in direct proportion to the oxygen utilized and a lack of oxygen blocked both of them. The fraction of glucose trans formed into lactate was maximal during insulin-induced hypoglycemia. These glucose-starved tumors did not produce lactate during glucose refeeding despite a large glucose utilization. Neither lack of oxygen nor large glucose consumption appeared to be the dominant causes of in vivolactate production by tumors. Experimental increases in the lactate content of subcutaneous tissue could be obtained in the absence of any tumor. The possibility that glycolysis is related to changes of cellular com ponents not necessarily involved in the neoplastic process is suggested.