Macromolecular turnover in mice (C57BL times C3H) liver, thymus and kidney after partial hepatectomy

Studies have been presented concerning the definition of bioassay systems, in terms of macromolecular kinetics as it pertains in advance to ENU carciogenic sensitivity. Male mice (C57BL female times C3H male) 6 weeks of age were partially hepatectomized and labelled with thymidine 3-H, uridine 3-H and leucine 3-H as precursors for DNA, RNA and protein synthesis respectively. Specific activity of all these three parameters of liver, thymus and kidney were followed for 5 days at regular intervals, and for 6 weeks at randomly chosen intervals. The goal of this study which we obtained, is a three-phased curve in liver for each macromolecule studied; RNA synthesis reached its first peak 18 hours, protein synthesis 24 hours, and DNA synthesis 30 hours after partial hepatectomy. Synthetic macromolecular turnover in other organs (thymus, lung, kidney, brain) were not affected in a similar way, inspite expecting some factors of a humoral nature. An accurate knowledge of the timing in macromolecular synthesis after partial hepatectomy in mice is an essential preliminary study for the development and definition of a model protocol for ENU--single dose having approximately 10-15 minutes half-life carcinogenic response.