Liver ultrastructure and RNA labelling after partial hepatectomy in protein-fed and protein-deprived rats.

Abstract

Male rats were pair-fed on a protein-free or a 25% casein diet for 14-days and then submitted to partial hepatectomy or sham operation. As seen in the electron microscope, both dietary groups of hepatectomized rats showed about the same degree of regeneration of rough-surfaced endoplasmic reticulum and polysomes, and the same enlargement of nucleoli. The nucleoli of the regenerating livers of protein-deprived rats often showed an increase in the granular component. The RNA labelling after cytidine-3H administration, studied by radioautography and by polyacrylamide-agarose gel electrophoresis of total liver and a cytoplasmic fraction, was heavier in all parts of the liver cell in protein-deprived rats as compared to protein-fed rats and heavier in hepatectomized than in sham-operated rats. There was no delay in the appearance of 29 and 18 S ribosomal RNA in the cytoplasm in protein-deprived and hepatectomized rats. The results suggest that the protein-deprived rats have a good ability to regenerate liver cell structures after partial hepatectomy, that their enlarged liver cell nucleoli have a high synthesis of RNA, and that the processing and delivering of nucleolar RNA to the cytoplasm proceeds in a normal way.