Induction of liver mixed function oxygenase system by beta- & gamma-hexachlorocyclohexane.
The y- isomer of hexachlorocydohexane(HCH) was a more powerful inducer ofmilted function oxygenase system (M FOS) 
than the beta- isomer, although the increases in liver weights were more in beta-HCH-treated rats. Induction of MFOS by these HCH 
isomers was dose-dependent even 50 ppm dietary level (or 2 weeks was effective. MFOS induction was nearly maximum at the 
end of 4 days treatment. Increases in cytochromes P450 and bs, produced by these compounds were not associated with 
stimulation of heme synthesis. Stimulation of cytochromes, O-hydroxylase, and N-demethylase by HCH isomers and 
phenobarbital was not additive when administered togetber. /1- or)'- HCH and phenobarbital produced an additive effect on 
the induction ofNADPH-eytochrome reductase. Exogenous administration of hematin counteracted the induction ofMFOS 
by HeH isomers, as in the case of phenobarbital.