Comparative Biochemistry of Hepatomas: IV. Isotope Studies of Glucose and Fructose Metabolism in Liver Tumors of Different Growth Rates^*

The metabolic fate of labeled fructose and glucose was compared in normal liver and in hepatomas of different growth rates. For certain biochemical parameters a rough correlation with the growth rates of liver tumors was observed.

The metabolic disposition of both fructose and glucose was in the same range in the control tissues, and no strain difference could be discerned.

The fructose uptake was decreased to 48 per cent or less in all hepatomas. The CO₂ production was decreased to 67 per cent or less. Very little glycogen synthesis from fructose occurred in the slowly growing tumors; however, incorporation was normal or increased in the rapidly growing ones. There was a tendency to decreased glucose production, and all glucose release values were 11 per cent or less of those of the normal. The initial glycogen levels in all tumors were markedly less than those observed in livers of control animals. Lactate production was less than normal in the slowly growing tumors, with normal or slightly increased values in the rapidly growing ones.

The maximum glucose phosphorylation was decreased in the examined tumors, with the exception of H-35. The oxidation of C-1 as well as C-6 of glucose showed a tendency to increase parallel with the increase in growth rate of the hepatomas. The C-1/C-6 ratio in CO₂ was in the normal range in the slowly growing tumors but was increased in the rapidly growing hepatomas. The glucose to glycogen ratio also increased with the increased growth rate. The net lactate production observed with glucose present as added substrate was normal for H-35, but in the more rapidly growing hepatomas was markedly increased roughly parallel with the increasing growth rate of the tumors.