Metabolism of neoplastic tissue. X. Diphosphopyridine nucleotide levels during azo dye hepatocarcinogenesis.

Summary Levels of oxidized and reduced diphosphopyridine nucleotide were determined in rat liver under various conditions, and in the preneoplastic liver and liver tumors derived from azo dye feeding. In contrast with results of previous investigators, no appreciable effect of fasting was observed on either nucleotide. Their levels were low in embryonic and newborn liver, but reached the adult level in 5–7 days and remained constant thereafter. Primary tumors arising in livers of rats fed p -dimethylaminoazobenzene had low levels of both nucleotides, these being in the ranges observed for transplanted tumors. Nontumorous liver adjacent to the tumors displayed levels only slightly lower than those of normal liver. Livers of animals fed the potent carcinogen, 3′-methyl-4-dimethylaminoazobenzene, showed a progressive lowering in DPN + and DPNH content with increasing time on the diet, to about three-fourths of the normal levels, but these values were always considerably higher than those of the primary tumors. Despite the preneoplastic pathology, livers of rats fed hepatic carcinogens do not have markedly different levels of DPN + and DPNH from normal rat livers.