General Red Cell Metabolism

Brewer, George J.

doi:10.1016/b978-0-12-677201-2.50015-5

Cited by 30 publications

(10 citation statements)

References 172 publications

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“…The nucleotides of mammalian erythrocytes undergo turnover as shown by both in vitro (Lowy, Ramot & London, 1960;Bishop, 1960) and in vivo studies (Lowy, Ramot & London, 1958;Bishop, 1961). These cells lack some of the enzymes required for de novo adenine biosynthesis, and both adenine and adenosine have been considered as possible precursors for adenine nucleotide synthesis (Meyskens & Williams, 1971;Brewer, 1974). A second possibility is that inosine may be acting as an energy source in addition to glucose.…”

Section: Discussionmentioning

confidence: 99%

“…Bases and monosaccharides are not substrates for this system. Kinetic analyses (Cabantchik & Ginsburg, 1977) and inhibitor binding experiments (Pickard, Brown, Paul & Paterson, 1973;Cass, Gaudette & Paterson, 1974;Pickard & Paterson, 1976) have emphasized the usefulness of the erythrocyte in studies of the detailed mechanism of nucleoside translocation across cell membranes in general, but 326J.DYON there is little direct evidence concerning the physiological significance of nucleoside transport in these cells (see for example Brewer, 1974;Berlin & Oliver, 1975).…”

Section: Introductionmentioning

confidence: 99%

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Nucleoside transport in sheep erythrocytes: genetically controlled transport variation and its influence on erythrocyte ATP concentrations.

Young¹

1978

The Journal of Physiology

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SUMMARY1. The permeability of sheep erythrocytes to purine and pyrimidine nucleosides was investigated. Erythrocytes from most sheep (nucleoside-impermeable) were almost completely impermeable to 5 mM inosine whereas cells from approximately 5 % of the animals studied (nucleoside-permeable) showed a rapid inosine uptake.Cells from both types of animal were permeable to 5 mm adenosine, although transport was slower in nucleoside-impermeable erythrocytes.2. Two distinct nucleoside transport routes were present in nucleoside-permeable erythrocytes; a high affinity (apparent Km -0-2 mM) facilitated diffusion system which transported both purine and pyrimidine nucleosides, and a non-saturable uptake route selective for adenosine. The high affinity system was the major route of adenosine transport at physiological concentrations. 3. Transport by the high affinity system was completely inhibited by micromolar concentrations of dipyridamole and nitrobenzylthioinosine. Dipyridamole had no effect on the non-saturable component of adenosine uptake.4. The transport differences between nucleoside-permeable and impermeable erythrocytes were due to the absence of the high affinity system from nucleosideimpermeable cells.5. Nucleoside-permeable cells had a higher intracellular ATP concentration than nucleoside-impermeable erythrocytes, suggesting that the high affinity transport system participates in the energy metabolism of the cell.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nucleoside transport in sheep erythrocytes: genetically controlled transport variation and its influence on erythrocyte ATP concentrations.

Young¹

1978

The Journal of Physiology

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“…Since the glycolytic rate cannot be increased more than threefold (23), it is reasonable to suspect that the availability of ATP in MAJ cells would be rate limiting for the operation of the Na+/K+ pump. Fig.…”

Section: Nao+-nat Exchangementioning

confidence: 99%

Properties of the Na+-K+ pump in human red cells with increased number of pump sites.

Halperin¹,

Brugnara²,

Kopin³

et al. 1987

J. Clin. Invest.

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We studied the Na+/K+ pump in red cells from an obese human subject (MAJ) id which the number of pumps/cell was 10-20 times higher than normal., Through measurements of the kinetic properties of several modes of operation of the Na+/K+ pump we determined that the pumps in MAJ cells are kinetically normal. In the presence of adequate metabolic substrate the maximum rates of Na+ pumping and lactate production saturated at 60 and i2 mmol/1 cell per h, respectively. Under physiological conditions pump and "leak" Na+ fluxes were similar in MAJ and normal cells, Since internal Na+ was lower in MAJ than in normal cells (Na+ -2 and 8 mmol/1 cell, respectively), we conclude that the reduction in cell Na+ allows the Na+/K+ pump in MAJ cells to operate at lower fraction of maximum capacity and to compensate for the increased number of pumps.

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“…Hexokinase (HK; EC 2.7.1.1) is the first enzyme and a crucial rate-limiting step in the glycolytic pathway [1]. In 1965, Lohret al [2] described the first HK deficiency as sociated with decreased affinity for glu cose and Mg-ATP in 3 patients with multi ple abnormalities and a Fanconi's pan myelopathy.…”

Section: Introductionmentioning

confidence: 99%