Ribonucleic acid synthesis in relation to precursor pools in regenerating rat liver

Abstract

The rate of RNA synthesis during the early stages of hepatic regeneration has been evaluated with radioactive precursor techniques. Since RNA labeling is influenced by alterations in effective liver mass, size of endogenous precursor pools, and possibly other factors as well as by regenerative activity, the experimental procedures were modified to permit estimation of RNA biosynthetic rates in terms of mμmoles of nucleoside triphosphate incorporated — conditions which permitted more meaningful comparisons than heretofore among rats differing in nutritional status, size of liver cell complement, or dose of labeled precursor. When regenerating liver was examined under these new conditions, we found that the endogenous UTP and CTP pools expanded by 50% or more within 3 h after partial hepatectomy, and the rate of RNA synthesis, after a negligible depression at time zero, rose by 50–100% at 3–6 h and then remained level for an additional 6 h. RNA content followed similar trends. Sham operation caused minor transient rises in pool size, biosynthetic rate and RNA content.