1. The injection of substrate amounts of lactate into newborn rats produced an increase in the concentration of phosphoenolpyruvate in liver. Similar experiments with foetal rats showed no increase in phosphoenolpyruvate concentration although pyruvate formation was observed. 2. The administration of pyruvate to foetal rats was also without effect on the hepatic phosphoenolpyruvate concentration, although a 20-fold increase in this was observed when pyruvate was injected into newborn animals. 3. Analogous experiments with aspartate produced qualitatively similar differences between foetal and newborn rats. 4. When [14C]-lactate, -pyruvate or -aspartate was injected into foetal or newborn rats incorporation of radioactivity into liver glucose was observed only in the newborn animals. 5. Lactate/pyruvate ratios of 213 in foetal liver and 13·5 in the livers of newborn rats indicated a relatively reduced environment in the cytosol of foetal liver. This difference in redox state was illustrated experimentally by a greater conversion of pyruvate into lactate and an increased formation of malate in foetal liver. 6. Although both the substrate-loading and tracer experiments indicated a block in gluconeogenesis in foetal liver at the stage of conversion of oxaloacetate into phosphoenolpyruvate, gluconeogenesis was also hindered by a highly reduced environment.
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July 1969
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Research Article|
July 01 1969
The development of gluconeogenesis in rat liver. Experiments in vivo
Helen Philippidis;
Helen Philippidis
1Fels Research Institute and Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pa. 19140, U.S.A.
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F. J. Ballard
F. J. Ballard
1Fels Research Institute and Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pa. 19140, U.S.A.
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Publisher: Portland Press Ltd
© 1969 The Biochemical Society
1969
Biochem J (1969) 113 (4): 651–657.
Citation
Helen Philippidis, F. J. Ballard; The development of gluconeogenesis in rat liver. Experiments in vivo. Biochem J 1 July 1969; 113 (4): 651–657. doi: https://doi.org/10.1042/bj1130651
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