Effects of 7,12-Dimethylbenz [a] Anthracene on RNA Polymerase in Isolated Mammary Gland Cell Nuclei 1

Summary

A method for isolation of mammary gland cell nuclei was described. DNA-dependent RNA polymerase activity in isolated mammary gland nuclei was measured in rats fed a single dose of DMBA. In female rats, there was a significant inhibition of Mn²⁺-(NH⁴)₂SO₄-activated RNA polymerase activity within 24 hr after the feeding of DMBA. Inhibition continued for 2 days, but thereafter, the enzyme activity rose significantly above the control value. In contrast, RNA polymerase activity was not depressed in male rats treated with DMBA.