Dietary regulation of phosphoglucose isomerase (PGI) and phosphoglycerate kinase activity (PGK) in rat liver after feeding 2-acetylaminofluorene (AAF)

Alterations in enzyme induction are well known to occur in the liver of animals after administration of carcinogens. This effect is believed to be specific to carcinogens. If this is true, it might be utilized for testing chemical substances for carcinogenicity. To obtain further information about this process, the dietary induction of the activity of PGI and PGK in livers of 3-day fasted rats before and after a 30 hour refeeding period with 60 % sucrose diet was investigated after feeding a 0.03 % AAF-containing diet for 2 or 4 weeks.

The induced acitvity of PGI was statistically significantly lower in the animals pretreated with the carcinogen for 2 or 4 weeks than in the nontreated control animals, even after subsequent feeding carcinogen-free diet for 2 weeks.

Refeeding led to a pronounced induction of PGK activity solely after 2 weeks duration of the experiment. In contrast to PGI, the activity of PGK estimated after refeeding was significantly higher in the rats pretreated with AAF for 2 and 4 weeks than in the non-treated control animals. However, in the rats fed AAF, the basal level of activity estimated after fasting was elevated to a similar extent and, therefore, enhanced induction does not seem to be the cause of this effect.