scholarly journals Proton-sulfate co-transport: mechanism of H+ and sulfate addition to the chloride transporter of human red blood cells.

1982 ◽  
Vol 79 (1) ◽  
pp. 87-113 ◽  
Author(s):  
M A Milanick ◽  
R B Gunn
Keyword(s):  
Blood Cells ◽  
Transport Mechanism ◽  
Molecular Mechanisms ◽  
The Other ◽  
Chloride Flux ◽  
Sulfate Ions ◽  
Human Red Blood Cells ◽  
Anion Transporter ◽  
Mechanism Of Reaction ◽  
Chloride Exchange

Proton and sulfate inhibition of the obligatory chloride-chloride exchange of human erythrocytes was measured at 0 degrees C to determine their mechanism of reaction with the anion transporter. The proton and sulfate that are co-transported by this mechanism at higher temperatures behaved as nontransported inhibitors at 0 degrees C. We analyzed the data in terms of four molecular mechanisms: (1) HSO4- addition to the transporter; (2) ordered addition with the proton first; (3) ordered addition with the sulfate first; (4) random addition to the transporter. The Dixon plots of 1/MCl vs. [SO4] at different proton concentrations were not parallel. Thus protons and sulfate ions were not mutually exclusive inhibitors. The slope of these Dixon plots was independent of pH above 7.0, which indicates that sulfate could bind to the unprotonated carrier and excludes the first two mechanisms. Protons were inhibitors of chloride flux in the absence of sulfate, which indicates that protons could bind to the unloaded carrier and excludes mechanism 3. The KI for sulfate was 4.35 +/0 0.36 mM. The pK for the protonatable group was 5.03 +/- 0.02. The binding of either a proton or sulfate to the carrier decreased the KI of the other by ninefold. The only simple mechanism consistent with the data is a random-ordered mechanism with more transporters loaded with a sulfate than loaded with a proton at the pH and sulfate concentrations of plasma.

scholarly journals Characteristics of Chloride Transport in Human Red Blood Cells

1973 ◽  
Vol 61 (2) ◽  
pp. 185-206 ◽  
Author(s):  
Robert B. Gunn ◽  
Mads Dalmark ◽  
D. C. Tosteson ◽  
J. O. Wieth
Keyword(s):  
Steady State ◽  
Blood Cells ◽  
Transport Mechanism ◽  
Chloride Transport ◽  
Human Erythrocytes ◽  
Hydrogen Ions ◽  
Chloride Flux ◽  
Human Red Blood Cells ◽  
Functional Forms ◽  
Exchange Flux

The efflux of chloride-36 from human erythrocytes under steady-state conditions is a saturable process that is competitively inhibited by bicarbonate and noncompetitively inhibited by acetate. This chloride self-exchange flux is reversibly dependent on the pH of the medium between 5.7 and 9.6 with a maximum flux at pH 7.8. The increase in chloride flux between pH 5.7 and 7.8 is inexplicable by the fixed charge hypothesis. The interpretations are made that chloride transport in human erythrocytes is carrier mediated, that bicarbonate utilizes the same transport mechanism, and that the mechanism can be titrated with hydrogen ions into less functional forms for chloride transport.

scholarly journals Influence of gemfibrozil on sulfate transport in human erythrocytes during the oxygenation-deoxygenation cycle

2008 ◽  
pp. 621-629
Author(s):  
E Tellone ◽  
S Ficarra ◽  
R Scatena ◽  
B Giardina ◽  
A Kotyk ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Significant Role ◽  
Blood Cells ◽  
Band 3 ◽  
Macromolecular Complex ◽  
Sulfate Transport ◽  
Human Red Blood Cells ◽  
Anion Transporter ◽  
Chicken Erythrocytes ◽  
T State

The effects of gemfibrozil (GFZ), an antihyperlipidemic agent, on the anionic transport of the human red blood cells (RBC) during the oxygenation-deoxygenation cycle were examined. Gemfibrozil clearly plays a role in the modulation of the anionic flux in erythrocytes; in fact it causes a strong increment of anions transport when the RBCs are in the high-oxygenation state (HOS). Such an effect is remarkably reduced in the lowoxygenation state (LOS). With the aim of identifying the dynamics of fibrate action, this effect has been investigated also in human ghost and chicken erythrocytes. These latter, in fact, are known to possess a B3 (anion transporter or Band 3) modified at the cytoplasmic domain (cdb3) which plays a significant role in the metabolic modulation of red blood cells. The results were analyzed taking into account the well-known interactions between fibrates and both conformational states of hemoglobin i.e. the T state (deoxy-conformation) and the R state (oxy-conformation). The effect of gemfibrozil on anionic influx appears to be due to a wide interaction involving a “multimeric” Hb-GFZ-cdb3 macromolecular complex.

scholarly journals Coronavirus SARS-CoV-2: Hypotheses of Impact on the Circulatory System, Prospects for the Use of Perfluorocarbon Emulsion, and Feasibility of Biophysical Research Methods

2020 ◽  
Vol 16 (3) ◽  
pp. 4-13 ◽  
Author(s):  
V. V. Moroz ◽  
A. M. Chernysh ◽  
Elena K. Kozlova
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Molecular Mechanisms ◽  
Circulatory System ◽  
High Resolution Spectroscopy ◽  
Perfluorocarbon Emulsion ◽  
Erythrocyte Morphology ◽  
Force Microscopy ◽  
Human Red Blood Cells ◽  
Atomic Force

This paper highlights published hypotheses on the possibility of coronavirus SARS-CoV-2 entry into the bloodstream, its interaction with vascular endothelium, red blood cells, hemoglobin and its fragments. As a result of such interaction, iron ions may be released into the bloodstream and, subsequently, a cytokine storm may occur. In this context, it is important to find a cytoprotective agent capable of blocking such processes. The perfluorocarbon emulsion could be a candidate for this role.The aim of the paper is to show the feasibility of biophysical methods to study the molecular mechanisms of action of SARS-CoV-2 on human red blood cells and hemoglobin as well as the restorative and cytoprotective effect of the perfluorocarbon emulsion during Fe2+ oxidation in heme.Materials and methods. High resolution spectroscopy, atomic force microscopy, atomic force spectroscopy, electroporation were used. Blood was exposed to oxidizing agents of different nature. Perfluorocarbon emulsion was added in various concentrations and its effect at various incubation times was studied. Concentration of hemoglobin derivatives was calculated considering multicollinearity, and statistical analysis of the results was performed.Results. The perfluorocarbon emulsion was shown to have an effective restorative and cytoprotective action in iron ion oxidation in the heme: Fe3+ was restored to Fe2+. The degree of MetHb reduction to HbO2 and Hb depended on the concentration of the oxidizing agent and incubation time. We observed a change in MetHb content from 80-90% to 5-12%. The perfluorocarbon emulsion in clinical concentrations helped eliminate local membrane defects and restored normal erythrocyte morphology.Conclusion. In the light of the studied hypotheses, the use of perfluorocarbon emulsion can become an effective method for blocking the consequences of coronavirus effect on the blood cells and restoring a normal gas exchange.

scholarly journals Engagement rules that underpin DBL-DARC interactions for ingress of Plasmodium knowlesi and Plasmodium vivax into human erythrocytes

2017 ◽  
Author(s):  
Manickam Yogavel ◽  
Abhishek Jamwal ◽  
Swati Gupta ◽  
Amit Sharma
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Molecular Mechanisms ◽  
Plasmodium Knowlesi ◽  
Interaction Model ◽  
Comprehensive Overview ◽  
Human Red Blood Cells ◽  
Ligand Interactions ◽  
Erythrocyte Binding ◽  
Integration Sites

SummaryThe molecular mechanisms by which P. knowlesi and P. vivax invade human red blood cells have long been studied. Malaria parasite erythrocytic stages comprise of repeated bursts of parasites via cyclical invasion of host RBCs using dedicated receptor-ligand interactions. A family of erythrocyte-binding proteins (EBPs) from P. knowlesi and P. vivax attach to human Duffy antigen receptor for chemokines (DARC) via their Duffy binding-like domains (Pv-DBL and Pk-DBL respectively) for invasion. Here, we provide a comprehensive overview that presents new insights on the atomic resolution interactions that underpin the binding of human DARC with Pk/Pv-DBLs. Based on extensive structural and biochemical data, we provide a novel, testable and overarching interaction model that rationalizes even contradictory pieces of evidence that have so far existed in the literature on Pk/Pv-DBL/DARC binding determinants. We address the conundrum of how parasite-encoded Pk/Pv-DBLs recognize human DARC via its two sulfated tyrosine residues. We collate evidence for two distinct DARC integration sites on Pk/Pv-DBLs that together likely engage the DARC’s sulfated extracellular domain. These analyses are important for both malaria vaccine and inhibitor development efforts that are targeted at abrogating Pk/Pv-DBL/DARC coupling as one avenue to prevent invasion of P. vivax into human red blood cells.

On haemolysis by anionic detergents

1957 ◽  
Vol 146 (923) ◽  
pp. 225-241 ◽  
Keyword(s):  
Cell Wall ◽  
Blood Cells ◽  
The Other ◽  
Slow Process ◽  
Ionic Detergents ◽  
Human Red Blood Cells ◽  
Lipoprotein Complex ◽  
Rapid Destruction ◽  
Anionic Detergents ◽  
Kinetics Of

The kinetics of haemolysis of human red blood cells by synthetic anionic detergents has been studied. It is shown that these detergents can destroy red cells by two mechanisms, which normally operate simultaneously, one leading to a rapid destruction of the cells whilst the other is a slow process. The rapid process involves the action of the detergent on free phospholipid in the cell wall. This component is easily removed from the cell membrane, and cells thus treated will not undergo rapid haemolysis. The slow process is identical with that by which most haemolytic agents (saponins, non-ionic detergents and butanol) act, and if it alone can operate yields percentage haemolysistime curves which are sigmoid in shape. This process takes place in several stages and seems to involve the slow breakdown of a lipoprotein complex on the cell surface. If phospholipid is removed from the cell wall, it is slowly replaced from phospholipid bound as lipoprotein or possibly by synthesis from metabolites in the membrane. The equilibria which maintain the structure of the cell wall are discussed.

scholarly journals The effect of aclarubicin (acl) on human erythrocytes

2011 ◽  
Vol 34 (1) ◽  
pp. 23-29
Author(s):  
Piotr Witczak ◽  
Agnieszka Marczak
Keyword(s):  
Reactive Oxygen Species ◽  
Blood Cells ◽  
Reduced Glutathione ◽  
Human Erythrocytes ◽  
The Other ◽  
Oxygen Species ◽  
Total Glutathione ◽  
Human Red Blood Cells ◽  
20 Nm

The effect of aclarubicin (acl) on human erythrocytesThe present study examines the influence of aclarubicin (ACL) on human red blood cells with a focus on the generation of reactive oxygen species (ROS). A statistically significant increase in ROS levels was observed for all the tested concentrations of aclarubicin (1-20 nM). The depletion of catalase activity and elevated metHb content were also observed. On the other hand, changes in reduced glutathione (GSH) and total glutathione concentrations were not statistically significant. The presented results confirm important role of ROS in ACL cytotoxic activity.

scholarly journals Some effects of low pH on chloride exchange in human red blood cells.

1975 ◽  
Vol 65 (6) ◽  
pp. 731-749 ◽  
Author(s):  
R B Gunn ◽  
J O Wieth ◽  
D C Tosteson
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Chloride Concentration ◽  
Low Ph ◽  
Chloride Ions ◽  
Ph Values ◽  
Human Red Blood Cells ◽  
Chloride Exchange ◽  
Red Cell Membranes ◽  
Exchange Flux

In order to test the range of pH values over which the titratable carried model for inorganic anion exchange is valid, chloride self-exchange across human red blood cells was examined between pH 4.75 and 5.7 at 0 decrees c. It was found that chloride self-exchange flux had a minimum near pH 5 and increased again with further increase in hydrogen ion activity. The Arrhenius activation energy for chloride exchange was greatly reduced at low pH values. The chloride flux at pH 5.1 did not show the saturation kinetics reported at higher pH values but was proportional to the value of the chloride concentration squared. In addition, the extent of inhibition of chloride self-exchange flux by phloretin was reduced at low pH. Our interpretation of these findings is that the carrier-mediated flux becomes a progressively smaller fraction of the total flux at lower pH values and that a different transport mode requiring two chloride ions to form the permeant species and having a low specificity and temperature dependence becomes significant below pH5. A possible mechanism for this transport is that chloride crosses red cell membranes as dimers of HCl at these very low pH values.

scholarly journals PHYSICOCHEMICAL EFFECTS OF ALDEHYDES ON THE HUMAN ERYTHROCYTE

1972 ◽  
Vol 53 (3) ◽  
pp. 809-818 ◽  
Author(s):  
P. S. Vassar ◽  
J. M. Hards ◽  
D. E. Brooks ◽  
B. Hagenberger ◽  
G. V. F. Seaman
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Negative Charge ◽  
The Other ◽  
Red Cell ◽  
Volume Changes ◽  
Cell Deformability ◽  
Red Cell Deformability ◽  
Human Red Blood Cells ◽  
Formaldehyde Treatment

The effects of formaldehyde, acetaldehyde, and glutaraldehyde on human red blood cells were investigated. It was found that (a) The surface negative charge of the erythrocytes at pH 7 was increased 10% by glutaraldehyde, but not by the other two aldehydes. (b) The effect of incomplete fixation of the red blood cells was demonstrated by hemoglobin leakage studies The leakage of hemoglobin subsequent to formaldehyde treatment was especially pronounced Acetaldehyde-fixed cells showed some leakage of hemoglobin after an hour of exposure to the fixative, whereas glutaraldehyde-fixed cells showed no hemoglobin leakage. (c) All three aldehydes caused K+ leakage during fixation. The concentrations of K+ in the fixing solutions all reached the same level, but whereas the leakage with glutaraldehyde was immediate, that with formaldehyde was more gradual and that with acetaldehyde reached a steady state only after 24 hr. (d) The effects of the aldehydes on red cell deformability and swelling revealed that glutaraldehyde hardened the cells within 15 min, formaldehyde within 5 hr, while acetaldehyde required at least 24 hr to produce appreciable fixation. (e) The hematocrit changes accompanying the fixation process depended upon cell volume changes and loss of deformability.

scholarly journals Differential reactivity of lysine residues of the red blood cell Ca2+ pump involved in the E1-E2 conformational equilibrium

1991 ◽  
Vol 279 (1) ◽  
pp. 121-127 ◽  
Author(s):  
C Donnet ◽  
A J Caride ◽  
H N Fernández ◽  
J P F C Rossi
Keyword(s):  
Atpase Activity ◽  
Blood Cells ◽  
Conformational Equilibrium ◽  
The Other ◽  
Apparent Dissociation Constant ◽  
Apparent Affinity ◽  
High Affinity ◽  
Human Red Blood Cells ◽  
Differential Reactivity ◽  
Lysine Residues

1. Modification of Lys residues of the Ca(2+)-ATPase from human red blood cells with methyl acetimidate (MA) inhibited up to 70% of the Ca(2+)-ATPase activity. Furthermore, calmodulin-activated p-nitrophenyl phosphatase activity was fully inhibited at non-limiting concentrations of MA. 2. Treatment with MA inhibited phosphorylation of the Ca(2+)-ATPase. 3. When the enzyme was treated with 7.2 mM-MA in the presence of 100 microM-Ca2+, Ca(2+)-ATPase activity was decreased by 33%, whereas when the membranes were treated with MA in the presence of 50 microM-VO4(3-), this activity was decreased by only 8%. 4. When membranes were either proteolysed or preincubated with 1 mM-Ca2+, MA quickly inactivated the Ca(2+)-ATPase (k = 1.2 min-1). On the other hand, inactivation of membranes preincubated in the absence of Ca2+ and Mg2+ was slow (k = 0.08 min-1). 5. When the activity was measured in the absence of calmodulin, MA decreased to the same extent the values of KCa (the apparent dissociation constant for Ca2+) and Vmax, but in the presence of calmodulin the treatment decreased Vmax. only. 6. The results are consistent with the idea that MA reacts readily with the Ca(2+)-ATPase when the enzyme is in an E1 conformation, but not an E2 conformation, and that, reciprocally, treatment of the enzyme with MA shifts the enzyme to E1. 7. Provided that Ca2+ is present, ATP, with low apparent affinity (K0.5 = 195 microM), protected against inactivation by MA. However, MA treatment did not change the Km values of either the high-affinity or the low-affinity site for ATP, suggesting that protection results from a shift to a conformation in which the Lys residues are inaccessible to MA.

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