The induction of synthesis of L-type pyruvate kinase in cultured rat hepatocytes.
Hepatocytes were isolated from preweaned neonatal and adult rats and maintained in primary monolayer culture. Cells from preweaned newborns possessed no L-type pyruvate kinase, nor did they synthesize the enzyme. Incubation for 48-72 h in culture medium supplemented with 2 mM-fructose and 0.1 microM-insulin induced the synthesis of L-type pyruvate kinase, as judged by increased enzyme activity and the increased incorporation of [3H]leucine into immunoprecipitable L-type pyruvate kinase. Hepatocytes isolated from 48 h-starved adult rats incorporated less [3H]leucine into L-type pyruvate kinase than did cells isolated from high-carbohydrate-diet-fed rats. The rate of enzyme synthesis by cells from 48 h-starved rats was increased by the inclusion of fructose and insulin in the incubation medium, after a lag phase of 24-48 h. After 4 days in culture in the presence of fructose and insulin, hepatocytes from 48 h-starved rats synthesized L-type pyruvate kinase at similar rates to hepatocytes isolated from high-carbohydrate-diet-fed rats.
D000367:Age Factors; D000818:Animals; D002478:Cells, Cultured; D004790:Enzyme Induction / Q000187:drug effects; D005632:Fructose / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis*; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D011770:Pyruvate Kinase / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation / Q000201:enzymology; D014886:Weaning
D007328:Insulin; D007527:Isoenzymes; D005632:Fructose; D011770:Pyruvate Kinase