hepatocytes

Isolated rat liver hepatocytes, previously depleted of gluta-thione (GSH) by treatment with diethylmaleate, were allowed to incorporate [3H]grycine into their GSH. Incubation of 3H-labelled cells with 14C-labelled (±)-/ran.s-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene ((±)-BP-7,8-dihydrodiol) or (±)-7j3,8a-dihydroxy-9a,10a-epoxy-7,8,9,10-tetrahydrobenzo[a]-pyrene ((±)-BPDE) revealed the formation of double labell-ed products. This together with evidence from amino acid analysis indicates formation of GSH-conjugates of the highly carcinogenic BP-derivatives. Incubation of hepatocytes isolated from 3-methylcholanthrene (MC) treated rats with ^-labelled (±)-BP-7,8-dihydrodiol or (±)-BPDE resulted in binding of radioactivity to DNA. Reduction of the in-tracelhilar level of GSH to ~ 40 % of the normal level resulted in an approximate Mold increase in the DNA-binding of either substrate. In addition there was a concurrent decrease in the amount of GSH-conjugates formed. These data clearly demonstrate that GSH participates in conjugation reactions with carcinogenic (±)-BP-7,8-dihydrodiol and (±>-BPDE and that the intracellular level of GSH is important in preven-ting reactive intermediates from reacting with the DNA in in-tact cells