Cell proliferation in rat liver: Nucleic acid ratios and thymidine uptake as related to dose of a toxicant, mesidine

Abstract

Analytical data for deoxyribonucleic acid (DNA), ribonucleic acid (RNA), total nitrogen (N), and dry weight of the livers of rats fed 2,4,6-trimethylaniline (mesidine) are presented. DNA increased, reflecting the increase in cell population. The RNA : DNA and N : DNA ratios decreased, as did dry weight per unit weight of tissue, reflecting the lower proportion of cytoplasmic material to nuclear material. The increase in cellular population was ascribed principally to new bile duct formation. There was a dose response to the toxicant, as indicated by the extent of deviations from normal for analytical data, gross pathology, and microscopic pathology. Increased cell proliferation in liver after 1 week of mesidine administration was reflected in an increased incorporation of thymidine-2- 14C into liver DNA, which suggests the usefulness of thymidine incorporation studies in detecting early toxic response where liver regeneration occurs.