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Keywords:

  • cytoimmunochemistry;
  • pyruvate kinase isoenzymes;
  • rat liver

ABSTRACT— Using immunofluorescence and double-labelled antisera L and M pyruvate kinase (PK), we show that PK is localized in hepatocyte cytoplasm. The response is modulated by different dietary and hormonal conditions. In physiological conditions, only L PK is noted: slight with normal diet (or 35μg of glucagon) and non-existent with starvation (or 350 μg of glucagon). L PK fluorescence is maximal after a carbohydrate-rich diet. In experimental or genetic (Zucker rat) hyperinsulinemia, hepatocytes are both L PK and M PK positive. After partial hepatectomy, this double specificity is found between 48 h and the 7th day. The decrease of PK fluorescence after starvation or glucagon concerns the L PK form of the enzyme. With exo- or endogenous insulin, the increase of PK (as insulinemia assays from Zucker rats or after partial hepatectomy confirm) is essentially due to the presence of M PK in hepatocytes.