Biochemical studies of promoters of carcinogenesis in rat liver

摘要

AbstractAdult female rats were orally dosed with 1/5 to 3/5 the published LD50 of either promoters or putative promoters of carcinogenesis hexachlorobenzene (HCB), α‐hexachlorocyclohexane (α‐HCH), kepone and toxaphene or noncarcinogens coumaphos, EDTA, caprolactam, 8‐hydroxyquinoline, titanium (IV) oxide, sodium diethyldithiocarbamate (DEDTC), and sucroseat 21 and 4 h before sacrifice. The promoters selected in this study were all of the halogenated hydrocarbon class. At doses of 1/5 to 3/5 the LD50, all four promoters or putative promoters induced rat hepatic ODC activity. The seven noncarcinogens produced several biochemical effects at doses of 1/5 the LD50: increased serum alanine aminotransferase activity (SGPT) (caprolactam and DEDTC), decreased hepatic cytochrome P‐450 content (DEDTC), and increased hepatic ODC activity (8‐hydroxyquinoline and DEDTC). None of the seven noncarcinogens caused hepatic DNA damage or coordinate induction of hepatic ODC and cytochrome P‐450. The results support the interpretation that several of these biochemical parameters are useful in distinguishing potential tumor promoters and n