Modification of pyruvate kinase isozymes in prolonged primary cultures of adult rat hepatocytes.

Pyruvate kinase isozymic changes were studied in the adult hepatocyte cultures, by electrophoretic, kinetic and immunological methods. We were able to maintain parenchymal cells from normal adult rat liver in non-proliferating monolayer cultures up to 10 days. Hepatocytes appeared to contain a dominant PK I type up to 4-5 days of culture. After day 5, PK III type was regularly present with PK I and after 7 days PK III type was always the only isozyme detected in culture. It must be pointed out that, by the Ouchterlony method and sometimes by electrophoresis, concentrated extracts from freshly isolated hepatocytes or starting hepatocyte cultures did also contain Pyruvate kinase PK III type. These results suggest that Pyruvate kinase III is present but partly repressed in the adult parenchymal cells and becomes derepressed in culture.