DNA synthesis has been measured by determining the extent of [3H]thymidine incorporation in regenerating female C57 mouse liver after two-thirds partial hepatectomy, in the liver of female C57 mice after ligation of the common bile duct and in IF × C57 F1 female mouse bladder following the luminal implantation of a glass bead. In regenerating mouse liver there were two waves of elevated DNA synthesis with maxima between 42 and 48 h and 60 and 66 h. There was a wave of increased mitosis with a maximum between 52-56 h. The second wave of increased DNA synthesis was followed by a period of poorly synchronised mitosis, Unlabelled ortho-aminoazotoluene did not significantly affect the magnitude or timing of DNA synthesis following partial hepatectomy. The binding of [3H]ortho-aminoazotoluene to liver DNA, RNA and protein was similar to that in non-hepatectomised mice during the periods of increased DNA synthesis and the second period of increased mitosis. During the first wave of mitosis binding to DNA was increased to 6 times its normal level. Ligation of the common bile duct increased DNA synthesis two-fold over 24 h but did not affect binding of ortho-aminoazotoluene to DNA. Implantation of a glass bead into the bladder lumen increased DNA synthesis two-fold but had no significant effect on DNA binding of the drug.
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