Scintillometric determination of unscheduled DNA synthesis in primary cultures of rat-liver cells. A hydroxylapatite batch assay.

A new procedure has been examined for measuring unscheduled DNA synthesis (UDS) in hepatocyte primary cultures by liquid-scintillation counting. DNA of the hepatocyte lysates was eluted with K-phosphate buffers after absorption on hydroxylapatite in order to reduce the background produced by cytoplasmic radioactivity. To inhibit hepatocyte replicative synthesis, hydroxyurea (10 mM) and cytosine arabinoside (80 microM) were added to the cultures. This procedure was found capable of detecting UDS elicited by 0.3 - 10 mM N-nitrosodimethylamine.