[Content of polyribosomes and poly-A-containing RNA in rat liver during hepatocarcinogenesis induced by diethylnitrosamine].

The contents of total polyribosomes and the ratio of free to membrano-bound polyribosomes as well as the number of poly(A)-containing RNA in cytoplasm and in two classes of polyribosomes of the liver were studied in rats chronically treated with diethylnitrosamine. A decrease in the number of total polyribosomes and changes in the ratio of free to membrane-bound polyribosomes toward a decrease of the latter were found within the whole period of carcinogenesis. The absolute amount of the free polyribosomes per 1 gr of the liver tissue did not differ significantly from the normal values but the number of the membrane-bound polyribosomes in the treated animals was 2-2,5 times as low. The amount of poly(A)-containing RNA in the postmitochondrial fraction increased and decreased in free polyribosomes. A redistribution of the templates by free and membrane-bound polyribosomes in cytoplasm of the hepatocytes during hepatocarcinogenesis due to the disturbances in the equilibrium between these two classes of polyribosomes is suggested.