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The Carbohydrate Metabolism of the Brown-Pearce Carcinoma of the Rabbit in Normal and Hypoglycemic Serum^*

( Department of Vital Economics, University of Rochester School of Medicine and Dentistry, Rochester, N.Y.)

1. A study was made to determine the extent to which the metabolism of the Brown-Pearce tumor could be altered by lowering the circulating glucose level with insulin. The metabolism of tumor slices was investigated in normal sera from rabbits which had been on a fast and in sera prepared from animals in insulin shock. Oxygen consumption was measured manometrically and aerobic lactic acid production determined colorimetrically.

2. Six experiments were conducted in which the glucose level of the shock sera was restored approximately to normal or above, and six in which the effect of the addition of glucose to normal serum was ascertained. A graph showing the relationship between serum glucose and Q_O2 values was determined.

3. The ratio of aerobic lactic acid production to glucose consumption in normal serum was ascertained. The ratio of aerobic glycolysis to equivalent respiration was calculated by data determined chemically and data determined manometrically.

4. The oxygen consumption of Brown-Pearce tumor slices is increased by 17.2 per cent and the aerobic lactic acid production decreased to 50 per cent in sera prepared from animals in insulin shock, as contrasted to determinations made in sera taken from the same animals on fast for 14–24 hours.

5. The stimulating effect of hypoglycemic sera on oxygen consumption is destroyed by the addition of glucose.

6. A value of 0.63 was obtained for the ratio fo aerobic lactic acid production to glucose consumption in normal sera.

7. A comparison between the metabolism of tumors taken from rabbits on fast with that from those in insulin shock was made in CO₂-free Ringer's phosphate medium. No significant difference in Q_O2 and R.Q. values was found.

8. In the light of determinations by chemical methods, it appears that the Warburg ratio ascertained manometrically does not accurately reflect the extent of tumor glycolysis. It is concluded that the ratio of lactic acid produced to glucose consumed should be employed as a more precise index of carbohydrate metabolism.

^* This study was supported by a grant from the Committee on Endocrine Research of the National Research Council.

Received 11/16/50.