Cytoimmunochemical study of pyruvate kinase isoenzymes in rat liver.
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 35 micrograms of glucagon) and non-existent with starvation (or 350 micrograms 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.
D000818:Animals; D003593:Cytoplasm / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D006946:Hyperinsulinism / Q000201:enzymology; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism*; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D011770:Pyruvate Kinase / Q000032:analysis / Q000378:metabolism*; D051381:Rats
D007527:Isoenzymes; D011770:Pyruvate Kinase