Decreased synthesis of DNA in regenerating rat liver after the administration of reserpine.

1. Reserpine given to rats before the enhanced synthesis of DNA begins 14h after partial hepatectomy markedly depresses thymidine uptake into DNA at 24 hours.2. At this time decreased activity of liver thymidine kinase but unchanged thymidine 5'-nucleotidase were observed.3. Reserpine has no effect on DNA synthesis when administered simultaneously with the labelled thymidine 2 h before killing.4. With depressed DNA synthesis after reserpine administration there is no significant decrease of liver RNA synthesis.