In vivo-in vitro replicative DNA synthesis (RDS) test using perfused rat livers as an early prediction assay for nongenotoxic hepatocarcinogens: I. Establishment of a standard protocol.
To establish a standard protocol for an in vivo-in vitro hepatocyte replicative DNA synthesis (RDS) test using male F344 rats for screening nongenotoxic (the Ames-negative) hepatocarcinogens, experimental conditions were examined. After treatment with three model hepatocarcinogens, isolated hepatocytes showed highest RDS incidences when plated at a density of 5 x 10(4) cells/ml. Spontaneous RDS incidences in hepatocytes from rats aged 9 weeks or older showed a constant value. The use of hepatocytes from 9-week-old rats at the 5 x 10(4) cells/ml plating density was therefore determined as the standard. Based on the distribution of mean spontaneous RDS incidences over 105 additional experiments (0.4 +/- 0.18%, with SEM), an RDS incidence of over 1% was adopted as the criterion for a positive response in our rat liver RDS test.
Uno
Y
Y
Toxicology Laboratory, Mitsubishi Kasei Co., Yokohama, Japan.
Takasawa
H
H
Miyagawa
M
M
Inoue
Y
Y
Murata
T
T
Ogawa
M
M
Yoshikawa
K
K
D000367:Age Factors; D000818:Animals; D002251:Carbon Tetrachloride / Q000008:administration & dosage / Q000633:toxicity; D015197:Carcinogenicity Tests / Q000592:standards; D002273:Carcinogens / Q000633:toxicity*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002994:Clofibrate / Q000008:administration & dosage / Q000633:toxicity; D004261:DNA Replication / Q000187:drug effects*; D004054:Diethylstilbestrol / Q000008:administration & dosage / Q000633:toxicity; D008099:Liver / Q000166:cytology / Q000187:drug effects*; D008297:Male; D010477:Perfusion; D051381:Rats; D011916:Rats, Inbred F344
D002273:Carcinogens; D004054:Diethylstilbestrol; D002251:Carbon Tetrachloride; D002994:Clofibrate