Abstract
The activity of ITP pyrophosphohydrolase (ITP-ase) was measured in erythrocyte lysates of 48 healthy volunteers. This group could clearly be divided into two different polulations. Mean activity was 48.3 ± 13.1 nkat/g Hb (x ±SD, n=38) in one population, and only one-fourth thereof in the other population (11.4 ± 4.3 nkat/g Hb, n=10). In two subjects, previously selected because of high levels of ITP in fresh or stored erythrocytes, the ITP-ase activity was 0.2 and 2.4 nkat/g Hb, respectively.
In normal erythrocytes incubated in phosphate-rich buffer (20 mM), the rate of conversion of allopurinol, hypoxanthine and guanine to their respective nucleotides followed a biphasic pattern. Initial “salvage rate” was 130 nmol/l/s, which leveled of after 15 min to about 50 nmol/l/s. Exactly the same pattern was observed in erythrocytes from ITP-ase deficient subjects. Routine liquid preservation of erythrocytes from both groups in CPD-SAGMAN (containing citrate, phosphate, dextrose, sodium chloride, adenine, glucose and mannitol) resulted in a slow decline in salvage rate (0,7 % /day). The salvage rate of AICA (aminoimidazolecarboxamide) and AICA-riboside was 8 and 40 nmol/l/s, respectively.
We conclude that, despite the fact that the energy consumption in the IMP-ITP cycle can amount to up to 10 % erythrocyte energy turnover in vitro, ITP-ase deficiency and lack of activity in the IMP-ITP cycle, does not influence purine salvage.
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Van Waeg, G., Niklasson, F., Erlcson, Å. et al. 169 PURINE METABOLISM IN NORMAL AND ITP PYROPHOSPHOHYDRO-LASE-DEFICIENT ERYTHROCYTES. Pediatr Res 24, 139 (1988). https://doi.org/10.1203/00006450-198807000-00193
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DOI: https://doi.org/10.1203/00006450-198807000-00193