Effect of an Induced Synthesis of Pyridine Nucleotides in Vivo on the Metabolism of Ribonucleic Acid

Summary

The effect of a nicotinamide-induced stimulation of DPN synthesis on the metabolism of ribonucleic acid (RNA) in the normal and hypertrophying rat kidney was studied. The behaviors of the nuclear and cytoplasmic RNA were compared.

The turnover of RNA, as well as the neosynthesis of RNA and proteins during renal hypertrophy, were reduced to an extent proportional to the increase in DPN synthesis. The inhibition of RNA metabolism began in the nucleus, and the labile RNA was probably involved. A hypothesis is discussed which relates the inhibition of RNA synthesis by nicotinamide to a competition resulting from the utilization of ATP both for DPN synthesis and for the formation of nucleoside triphosphates and of RNA in the cell nucleus. Thus, DPN biosynthesis and nucleo-cytoplasmic relationships appear to be important factors in growth regulation.