[Features of poly-ADP-ribosylation and chromatin structure under conditions of varying NAD content in the rat liver].

It is shown that nicotinamide-induced in vivo stimulation of NAD biosynthesis in the liver nuclei of rats causes a decrease of the DNA sensitivity to treatment with DNAse I under conditions of weak hydrolysis. When rats are given synthetic vitamin PP-deprived food, the NAD level in the liver falls down to 40% and a great number of DNAse I-hypersensitive chromatin sites appear. A 24% decrease in the level of poly-ADP-ribosylation of total histones in comparison with the control has been observed with hypovitaminosis.