Abstract
Fructose loads induce a depletion of the hepatic purine nucleotides, followed by an increase of their "de novo" synthesis, which has been attributed to a conversion of glutamine-PRPP amidotransferase from its large inactive to its small active form (Itakura et al. J. Clin. Invest. 67 : 994, 1981). Addition of 5 mM fructose to isolated rat hepatocytes provoked, after a 10 min latency and within 1-2 min, a 6-10 fold increase of the concentration of PRPP above its basal value of 2-5 nmol/g of cells, which lasted for approx. 30 min. Fructose decreased hepatocyte ATP from 2 to 0.4 mM and Pi from 3.7 to 1.4 mM after 2 min. Thereafter both compounds increased gradually, reaching respectively 0.8 and 2.6 mM at 30 min. Fructose also increased progressively the concentration of ribose-5-P from 0.1 to 0.2 mM at 25 min. Under control conditions, approx. 5 % of 10 μM hypoxanthine (HX) added to the cell suspension was incorporated into the purine nucleotides. This value was not modified when HX was added 2 min after fructose but it increased approx. 5-fold when HX was added 30 min after fructose. The regeneration of the adenine nucleotides following fructose loads involves thus also an increased concentration of PRPP and an increased capacity for purine salvage. This occurs notwithstanding a depletion of ATP, one of the substrates of PRPP synthetase, and of Pi, its major stimulator.
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Vincent, F., Den, G., Berghe et al. EFFECT OF FRUCTOSE ON THE CONCENTRATION OF PRPP IN ISOLATED RAT HEPATOCYTES: 223. Pediatr Res 19, 781 (1985). https://doi.org/10.1203/00006450-198507000-00243
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DOI: https://doi.org/10.1203/00006450-198507000-00243
