Turnover of purine nucleotides in rabbit erythrocytes II. Studies in vitro

Hershko, Avram; Razin, A.; Shoshani, Tavassah; Mager, J.

doi:10.1016/0005-2787(67)90691-0

Cited by 64 publications

(21 citation statements)

References 29 publications

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“…In whole blood supplemented with glucose the rate of salvage is very low, and unphysiologically high concentrations of phosphate produce only a modest increase in the rate. Although a direct experimental comparison was not made, mouse erythrocytes appear to convert hypoxanthine to nucleotides more slowly than human or rabbit erythrocytes, based on the rates reported in the literature (22,23). Tax et a / .…”

Section: Discussionmentioning

confidence: 99%

Salvage of circulating hypoxanthine by tissues of the mouse

Moyer¹,

Henderson²

1983

Can. J. Biochem. Cell Biol.

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Hypoxanthine is an inefficient precursor of purine nucleotides in mouse tissues. In vitro, mouse erythrocytes salvage less than 10% of hypoxanthine (10 microM) added to whole blood in 30 min of incubation at 37 degrees C. In vivo, circulating hypoxanthine is rapidly degraded (greater than 90% in 10 min) to allantoin and uric acid. All tissues examined (other than erythrocytes) converted small amounts of hypoxanthine to nucleotides, with kidney and lung being the most active tissues examined. It is estimated that less than 2% of circulating hypoxanthine is salvaged in the mouse; the remainder is catabolized.

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Section: Discussionmentioning

confidence: 99%

Salvage of circulating hypoxanthine by tissues of the mouse

Moyer¹,

Henderson²

1983

Can. J. Biochem. Cell Biol.

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“…Mature erythrocytes lack the enzymes for de novo purine synthesis (1), but possess the ability to take up and release purine bases and nucleosides (2)(3)(4). Hypoxanthine is rapidly transported across the red cell membrane by facilitated diffusion, so that equilibrium is reached within a minute even at millimolar concentrations of the oxypurine (5).…”

Section: Introductionmentioning

confidence: 99%

Oxypurine cycle in human erythrocytes regulated by pH, inorganic phosphate, and oxygen.

Berman¹,

Black²,

Human³

et al. 1988

J. Clin. Invest.

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The effect of pH, P02, and inorganic phosphate on the uptake and metabolism of hypoxanthine by erythrocytes has been studied. Uptake of hypoxanthine and accumulation of inosine 5'-monophosphate (IMP) were markedly increased at acid pH, high external phosphate concentrations, and low Po2. Release of accumulated IMP as hypoxanthine occurred at alkaline pH values and low external phosphate concentrations. Conditions favoring IMP accumulation gave rise, in the absence of hypoxanthine, to a corresponding increase in 5'-phosphoribosyl-1-pyrophosphate. Intracellular phosphate concentrations were markedly pH dependent and a model is presented whereby hypoxanthine uptake and release are controlled by intracellular concentrations of inorganic phosphate and 2,3-bisphosphoglycerate. These allosteric effectors influence, in opposing ways, two enzymes governing IMP accumulation, namely 5'-phosphoribosyl-l-pyrophosphate synthetase and 5'-nucleotidase. These metabolic properties suggest that the erythrocyte could play a role in the removal of hypoxanthine from anoxic tissue.

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“…2 upper). Interestingly and perhaps significantly, the stability of adenine nucleotides in opossum red cells under the two different gas phases utilized in this study parallels that exhibited by rabbit and mouse red cells: significant "leakage" of adenine was documented in cells metabolizing under air or oxygen; none was detected when nitrogen served a s the gas atmosphere (Hershko et al, 1967). In contrast, Whelan and Bagnara (1979) reported ATP to be stable in human red cells during 90 minutes of incubation irrespective of the two gas atmospheres used.…”

Section: Discussionmentioning

confidence: 56%

“…Comparative erythrocyte physiology has yet to address the task of a n inquiry into the salvage and de novo synthesis of purine compounds in a systematic manner. It was nearly three decades ago that rabbit red cells were shown to be able to incorporate [14C] hypoxanthine (Hy) into both ATP and GTP (Lowy et al, 1961;Hershko et al, 1967). More recently Moyer and Henderson (1983) showed that mouse erythrocytes, in the presence of supraphysiologic Pi, were also able to incorporate radiolabelled Hy into ATP and GTP.…”

mentioning

confidence: 99%

Studies on the energy metabolism of opossum (Didelphis virginiana) erythrocytes: V. Utilization of hypoxanthine for the synthesis of adenine and guanine nucleotides in vitro

Bethlenfalvay

White

Chadwick

et al. 1990

Journal Cellular Physiology

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High pressure liquid radiochromatography was used to test the ability of opossum erythrocytes to incorporate tracer amounts of [G-3H] hypoxanthine (Hy) into [3H] labelled triphosphates of adenine and guanine. In the presence of supraphysiologic (30 mM) phosphate which is optimal for PRPP synthesis, both ATP and GTP are extensively labelled. When physiologic (1 mM) medium phosphate is used, red cells incubated under an atmosphere of nitrogen accumulate [3H] ATP in a linear fashion suggesting ongoing PRPP synthesis in red cells whose hemoglobin is deoxygenated. In contrast, a lesser increase of labelled ATP is observed in cells incubated under oxygen, suggesting that conditions for purine nucleotide formation from ambient Hy are more favorable in the venous circulation.

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Turnover of purine nucleotides in rabbit erythrocytes II. Studies in vitro

Cited by 64 publications

References 29 publications

Salvage of circulating hypoxanthine by tissues of the mouse

Salvage of circulating hypoxanthine by tissues of the mouse

Oxypurine cycle in human erythrocytes regulated by pH, inorganic phosphate, and oxygen.

Studies on the energy metabolism of opossum (Didelphis virginiana) erythrocytes: V. Utilization of hypoxanthine for the synthesis of adenine and guanine nucleotides in vitro

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