Relationship between the pentose phosphate shunt and methemoglobin reductase activity in human erythrocytes: Effect of aging on methemoglobin reductase activity

1979 ◽  
Vol 35 (8) ◽  
pp. 1112-1113
Author(s):  
C. Ioppolo ◽  
D. L. Currell ◽  
L. Civalleri ◽  
E. Antonini
Keyword(s):  
Reductase Activity ◽  
Pentose Phosphate ◽  
Human Erythrocytes ◽  
Pentose Phosphate Shunt

Reduction and uptake of methylene blue by human erythrocytes

2004 ◽  
Vol 286 (6) ◽  
pp. C1390-C1398 ◽  
Author(s):  
James M. May ◽  
Zhi-chao Qu ◽  
Charles E. Cobb
Keyword(s):  
Methylene Blue ◽  
Reductase Activity ◽  
Oxidant Stress ◽  
Pentose Phosphate ◽  
Human Erythrocytes ◽  
Dependent Manner ◽  
Phenylarsine Oxide ◽  
Concentration Dependent Manner ◽  
Ferricyanide Reduction ◽  
Thiazine Dye

A thiazine dye reductase has been described in endothelial cells that reduces methylene blue (MB), allowing its uptake into cells. Because a different mechanism of MB uptake in human erythrocytes has been proposed, we measured MB uptake and reduction in this cell type. Oxidized MB (MB+) stimulated reduction of extracellular ferricyanide in a time- and concentration-dependent manner, reflecting extracellular reduction of the dye. Reduced MB was then taken up by the cells and partially oxidized to MB+. Both forms were retained against a concentration gradient, and their redox cycling induced an oxidant stress in the cells. Whereas concentrations of MB+ <5 μM selectively oxidized NAD(P)H, higher concentrations also oxidized both glutathione (GSH) and ascorbate, especially in the absence of d-glucose. MB+-stimulated ferricyanide reduction was inhibited by thiol reagents with different mechanisms of action. Phenylarsine oxide, which is selective for vicinal dithiols in proteins, inhibited MB+-dependent ferricyanide reduction more strongly than it decreased cell GSH and pentose phosphate cycle activity, and it did not affect cellular NADPH. Open erythrocyte ghost membranes facilitated saturable NAD(P)H oxidation by MB+, which was abolished by pretreating ghosts with low concentrations of trypsin and phenylarsine oxide. These results show that erythrocytes sequentially reduce and take up MB+, that both reduced and oxidized forms of the dye are concentrated in cells, and that the thiazine dye reductase activity initially responsible for MB+ reduction may correspond to MB+-dependent NAD(P)H reductase activity in erythrocyte ghosts.

scholarly journals Intracellular Mg2+regulates ADP phosphorylation and adenine nucleotide synthesis in human erythrocytes

1998 ◽  
Vol 274 (5) ◽  
pp. E920-E927 ◽  
Author(s):  
Sarah Page ◽  
Michael Salem ◽  
Maren R. Laughlin
Keyword(s):  
Adenine Nucleotide ◽  
Phosphoglycerate Kinase ◽  
Pentose Phosphate ◽  
Human Erythrocytes ◽  
Maximal Velocity ◽  
Nucleotide Synthesis ◽  
Ion Concentrations ◽  
Net Flux ◽  
Normal Fluctuations ◽  
Phosphorylation Rate

13C- and31P-NMR were used in methylene blue-treated human erythrocytes to determine the dependence on intracellular Mg2+concentration ([Mg2+]i) of the pentose phosphate pathway (PPP), the glycolytic pathway, and adenine nucleotide synthesis. The PPP flux had an [Mg2+]iat half-maximal velocity ([Mg2+]i,0.5) of 0.02 mM, well below the physiological range (0.2–0.7 mM). Flux through the PPP was reduced at higher [Mg2+]ias flux through phosphofructokinase was increased ([Mg2+]i,0.5= 0.16 mM). [Mg2+]i,0.5of phosphoglycerate kinase flux, which equals net ADP phosphorylation rate, was 0.27 mM, well within the physiological [Mg2+]irange. The rate of adenine nucleotide synthesis from [2-13C]glucose-derived ribose 5-phosphate and exogenous adenine also exhibited dependence on [Mg2+]ibut was not saturable up to 1.6 mM. Therefore, net flux through the PPP and glycolytic pathways in erythrocytes is not strongly dependent on [Mg2+]iat physiological ion concentrations, but both ADP phosphorylation and adenine nucleotide synthesis are likely to be regulated by normal fluctuations in [Mg2+]i.

scholarly journals Impaired erythrocyte phosphoribosylpyrophosphate formation in hemolytic anemia due to pyruvate kinase deficiency

Blood ◽  
1988 ◽  
Vol 72 (2) ◽  
pp. 500-506 ◽  
Author(s):  
CR Zerez ◽  
MD Wong ◽  
NA Lachant ◽  
KR Tanaka
Keyword(s):  
Pyruvate Kinase ◽  
Hemolytic Anemia ◽  
Adenosine Triphosphate ◽  
Pyridine Nucleotide ◽  
Pentose Phosphate ◽  
Atp Depletion ◽  
Pyridine Nucleotides ◽  
Pyruvate Kinase Deficiency ◽  
Nucleotide Content ◽  
Pentose Phosphate Shunt

Abstract RBCs from patients with hemolytic anemia due to pyruvate kinase (PK) deficiency are characterized by a decreased total adenine and pyridine nucleotide content. Because phosphoribosylpyrophosphate (PRPP) is a precursor of both adenine and pyridine nucleotides, we investigated the ability of intact PK-deficient RBCs to accumulate PRPP. The rate of PRPP formation in normal RBCs (n = 11) was 2.89 +/- 0.80 nmol/min.mL RBCs. In contrast, the rate of PRPP formation in PK-deficient RBCs (n = 4) was markedly impaired at 1.03 +/- 0.39 nmol/min.mL RBCs. Impaired PRPP formation in these cells was not due to the higher proportion of reticulocytes. To study the mechanism of impaired PRPP formation, PK deficiency was simulated by incubating normal RBCs with fluoride. In normal RBCs, fluoride inhibited PRPP formation, caused adenosine triphosphate (ATP) depletion, prevented 2,3-diphosphoglycerate (DPG) depletion, and inhibited pentose phosphate shunt (PPS) activity. These results together with other data suggest that impaired PRPP formation is mediated by changes in ATP and DPG concentration, which lead to decreased PPS and perhaps decreased hexokinase and PRPP synthetase activities. Impaired PRPP formation may be a mechanism for the decreased adenine and pyridine nucleotide content in PK-deficient RBCs.

scholarly journals Regulatory Mechanism of Glutathione Reductase Activity in Human Red Cells

Blood ◽  
1974 ◽  
Vol 43 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Yoshihito Yawata ◽  
Kouichi R. Tanaka
Keyword(s):  
Glutathione Reductase ◽  
Hepatic Cirrhosis ◽  
Reductase Activity ◽  
Pentose Phosphate ◽  
Red Cells ◽  
Clinical Severity ◽  
Red Cell ◽  
Metabolic Pattern ◽  
Chronic Uremia ◽  
Glutathione Reductase Activity

Abstract The mechanism by which glutathione reductase (GR) activity is regulated in relation to flavin metabolism was studied in red cells of normal adults, cord blood, and patients with severe metabolic disorders using spectrophotometric, fluorometric, and radiochemical methods. The increased activity of GR in red cells of adult patients with severe hepatic cirrhosis, chronic uremia, and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is related to the increased per cent saturation of GR with flavin adenine dinucleotide (FAD), and increased red cell flavin level. The per cent saturation of GR with FAD correlates with (1) the degree of clinical severity in hepatic cirrhosis or chronic uremia, and (2) total flavin level in red cells. Thus, the increased GR activity in these patients may be regulated actively or passively by the increased flavin level in red cells. This suggests that the increased requirement for enhanced activity of the pentose phosphate pathway may affect GR metabolism secondarily, leading to the association of GR with FAD through an increased uptake of riboflavin. In contrast to the results in adult red cells, cord erythrocytes show an unexpected metabolic pattern of GR and flavin metabolism. Although the total GR activity of cord red cells is considerably higher than in adult red cells, cord red cell GR is only partly saturated with FAD even in the presence of a significantly increased flavin level in cord red cells. Thus, cord red cells may have an additional control mechanism of GR activity.

A STUDY OF GLYCOLYTIC AND PENTOSE PHOSPHATE SHUNT ENZYMES IN RELATIONSHIP TO THE ALTERED PERMEABILITY IN THE BLOOD-BRAIN BARRIER

1976 ◽  
Vol 26 (6) ◽  
pp. 1139-1143 ◽  
Author(s):  
M. J. Bennett ◽  
K. M. Ogilvy. ◽  
G. M. Blake ◽  
N. Lewtas ◽  
W. R. Timperley
Keyword(s):  
Blood Brain Barrier ◽  
Pentose Phosphate ◽  
Brain Barrier ◽  
Blood Brain ◽  
Pentose Phosphate Shunt

The Development of Glycolytic and Pentose Phosphate Shunt Enzymes in Human Brain

Neonatology ◽  
1977 ◽  
Vol 31 (3-4) ◽  
pp. 173-180 ◽  
Author(s):  
M.J. Bennett ◽  
W.R. Timperley ◽  
C.B. Taylor ◽  
A.S. Hill
Keyword(s):  
Human Brain ◽  
Pentose Phosphate ◽  
Pentose Phosphate Shunt

scholarly journals Effects of caffeine and other methylxanthines on the development and metabolism of sea urchin eggs. Involvement of NADP and glutathione.

1976 ◽  
Vol 68 (3) ◽  
pp. 440-450 ◽  
Author(s):  
J Nath ◽  
J I Rebhun
Keyword(s):  
Cell Division ◽  
Sea Urchin ◽  
Reductase Activity ◽  
Inhibitory Effect ◽  
Pentose Phosphate ◽  
Nad Kinase ◽  
Mitotic Apparatus ◽  
Sea Urchin Eggs ◽  
Glutathione Reductase Activity

Methylxanthines (MX) inhibit cell division in sea urchin and clam eggs. This inhibitory effect is not mediated via cAMP. MX also inhibit respiration in marine eggs, at concentrations which inhibit cleavage. Studies showed that no changes occurred in ATP and ADP levels in the presence of inhibitory concentrations of MX, indicating an extra-mitochondrial site of action for the drug. Subsequent studies revealed decreased levels of NADP+ and NADPH, when eggs were incubated with inhibitory concentrations of MX, but no change in levels of NAD+ and NADH. MX did not affect the pentose phosphate shunt pathway and did not have any effect on the enzyme NAD+ -kinase. Further studies showed a marked inhibitory effect on the glutathione reductase activity of MX-treated eggs. Reduced glutathione (GSH) could reverse the cleavage inhibitory effect of MX. Moreover, diamide, a thiol-oxidizing agent specific for GSH in living cells, caused inhibition of cell division in sea urchin eggs. Diamide added to eggs containing mitotic apparatus (MA) could prevent cleavage by causing a dissolution of the formed MA. Both MX and diamide inhibit a Ca2+-activated ATPase in whole eggs. The enzyme can be reactivated by sulfhydryl reducing agents added in the assay mixture. In addition, diamide causes an inhibition of microtubule polymerization, reversible with dithioerythritol. All experimental evidence so far suggests that inhibition of mitosis in sea urchin eggs by MX is mediated by perturbations of the in vivo thiol-disulfide status of target systems, with a primary effect on glutathione levels.

Sign in / Sign up

Export Citation Format

Share Document