Synthesis and secretion of albumin in rats during treatment with a carcinogenic dose of N-2-acetylaminofluorene.

The chronic administration of N-2-acetylaminofluorene (N-2-AAF) to rats causes a loss of hepatic cytoplasmic RNA, particularly from the endoplasmic-membrane fractions. At the end of the complete carcinogenic dose, the level of amino-acid incorporation into proalbumin is normal, despite the loss of 35% of membrane-bound RNA. The secretion of albumin, however, is inhibited. This inhibition of secretion is apparently the result of a change in membrane flow and differentiation; transfer of nascent protein from smooth-surfaced vesicles to the Golgi apparatus is blocked. The significance of these findings is discussed.