Nogalamycin effects in rat liver: inhibition of tryptophan pyrrolase induction and nucleic acid biosynthesis.

Abstract

In partially-hepatectomized and sham-operated rats, nogalamycin exhibits the same general patterns of inhibitory activity which are seen with actinomycin D: ( a ) Marked inhibition of orotate incorporation into RNA; ( b ) marked inhibition of thymidine incorporation into DNA at high drug levels only; and ( c ) little or no inhibition of valine incorporation into protein. Nogalamycin inhibited completely the hydrocortisone-induced increase in tryptophan pyrrolase activity but did not affect the substrate-induced increase. The inhibitory effects of nogalamycin administration were not detected after a 24-hr period. These results are compatible with the suggestion that nogalamycin interferes primarily with RNA, including messenger RNA, synthesis.