A procedure for examining deoxyribonucleic acid synthesis in regenerating liver in vitro

Abstract

When hepatic slices prepared from rats subjected to a 70% partial hepatectomy 16 hr earlier are incubated in vitro, they will progress through a wave of DNA synthesis in a manner similar to that seen in vivo. However, slices prepared at 14 hr post-hepatectomy will not initiate DNA synthesis when incubated in vitro. These results were not altered by the addition of either 5% or 20% serum (calf serum or fetal calf serum) to the incubation medium. These results are interpreted as indicating that between 14 hr and 16 hr after partial hepatectomy there exists a critical period during which exposure to a systemic factor(s) commits hepatic cells to enter a round of DNA synthesis. The experimental procedures outlined in this report provide a means to study, in vitro, progression through the S-phase in a normal mammalian cell population. In addition, experiments employing slices prepared at 14 hr post-hepatectomy might aid in discerning factors initiating the G 1 to S-phase conversion. The experimental protocol described is applicable to studies aimed at assessing selected aspects of the effects of drugs and putative toxicants on hepatic function.