Comparative study on pyruvate kinase activity-reducing action of various promoters of hepatocarcinogenesis

Chemicals such as PB, DDT, EED, sodium deoxycholate, thiobenzamide, orotic acid and SorFAE which enhance the formation of liver tumors or HN, caused a marked decrease in PK activity in Wistar rat liver that persisted for at least 4 weeks, though the decrease caused by EED was not so marked as that caused by other hepatic promoters. Non-promoting agents such as DH, and some chemicals, such as DEXA, testosterone and AB, which enhance the formation of GGT-positive foci in rat livers, but do not enhance the formation of tumors or HN, caused decreases in PK activity in some cases. Any such decreases, however, were only transient and normal levels were restored within 4 weeks. The results suggest that the continuous decrease in PK activity may be a useful marker in screening tests for the promoters of hepatocarcinogenesis.