Pyruvate kinase activity and the rates of gluconeogenesis and glycolysis in rat hepatocytes were evaluated by production of glucose and lactate + pyruvate from dihydroxyacetone during a feeding cycle or progressive starvation. In fed rats, during daylight (low food intake) and until darkness, gluconeogenesis progressively increased and glycolysis decreased slightly, but gluconeogenesis never exceeded glycolysis. During nocturnal feeding, gluconeogenesis and glycolysis returned to their morning rates. After 8 h starvation, an equal proportion of dihydroxyacetone was converted into glucose and into lactate + pyruvate. When glycogen was depleted (11 h of starvation), gluconeogenesis was maximal and glycolysis minimal. In fed and starved rats, the concentration of fructose 1,6-bisphosphate was the same. The activity ratio of pyruvate kinase (ratio of velocity at 0.5 mM-phosphoenolpyruvate to the maximum catalytic activity obtained with 4mM-phosphoenolpyruvate) was high in crude extracts of cells incubated with dihydroxyacetone and low in (NH4)2SO4-treated extracts, but remained unchanged during the whole experiment. There was no correlation between the rates of gluconeogenesis and glycolysis from dihydroxyacetone and the activity ratio of pyruvate kinase.
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March 1984
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Research Article|
March 15 1984
Development of gluconeogenesis from dihydroxyacetone in rat hepatocytes during a feeding cycle and starvation
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1984 London: The Biochemical Society
1984
Biochem J (1984) 218 (3): 975–981.
Citation
B Azzout, J Peret; Development of gluconeogenesis from dihydroxyacetone in rat hepatocytes during a feeding cycle and starvation. Biochem J 15 March 1984; 218 (3): 975–981. doi: https://doi.org/10.1042/bj2180975
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