Induction by 3-methylcholanthrene of microsomal cytochromes and enzyme activities in mouse liver after subchronic ingestion of cadmium chloride.
The dose-dependence of the effect of Cadmium chloride (Cd) on the induction by 3-methylcholanthrene (MC) of the microsomal cytochromes b5 and P-450, seven monooxygenase activities and the arylepoxide hydrase was investigated in the livers of male random bred mice (NMRI Hannover). The animals were treated with 6.0; 3.0; 1.0 and 0.3 mumoles Cd++/kg/day for 20 days and subsequently with MC for three days (20 mg MC/kg/day). Cytochrome P-450 of control animals receiving MC only was not induced, and presumably kinetic inhibition of three monooxygenase activities was observed at the highest Cd-dosage. However, treatment with the two intermediate Cd-dosages resulted in induction by MC of both microsomal cytochromes and of 5 hydroxylating activities, leaving unaffected only the arylhydrocarbon hydroxylase. Previous work had shown that Cd alone in this dose range is without effect on microsomal enzymes. Therefore, Cd exerts a stabilizing or permissive effect on the phenotypic expression of some microsomal enzymes, but not of the arylhydrocarbon hydroxylase, within the MC-dependent induction process in mouse liver.
D000818:Animals; D002104:Cadmium / Q000378:metabolism / Q000494:pharmacology*; D019256:Cadmium Chloride; D003580:Cytochromes / Q000096:biosynthesis*; D004790:Enzyme Induction / Q000187:drug effects; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D051379:Mice; D008862:Microsomes, Liver / Q000201:enzymology* / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000096:biosynthesis; D010641:Phenotype
D003580:Cytochromes; D002104:Cadmium; D008748:Methylcholanthrene; D006899:Mixed Function Oxygenases; D019256:Cadmium Chloride