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 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 Concentrative Accumulation of Choline by Human Erythrocytes

1968 ◽  
Vol 51 (4) ◽  
pp. 497-516 ◽  
Author(s):  
K. Martin
Keyword(s):  
Steady State ◽  
Human Erythrocytes ◽  
Electrochemical Gradient ◽  
Carrier System ◽  
Michaelis Constant ◽  
External Concentration ◽  
First Order ◽  
Maximum Flux ◽  
First Order Kinetics ◽  
Exchange Flux

Influx and efflux of choline in human erythrocytes were studied using 14C-choline. When incubated at 37°C with physiological concentrations of choline erythrocytes concentrate choline; the steady-state ratio is 2.08 ± 0.23 when the external choline is 2.5 µM and falls to 0.94 ± 0.13 as the external concentration is raised to 50 µM. During the steady state the influx of choline is consistent with a carrier system with an apparent Michaelis constant of 30 x 10-6 and a maximum flux of 1.1 µmoles per liter cells per min. For the influx into cells preequilibrated with a choline-free buffer the apparent Michaelis constant is about 6.5 x 10-6 M and the maximum flux is 0.22 µmole per liter cells per min. At intracellular concentrations below 50 µmole per liter cells the efflux in the steady state approximates first order kinetics; however, it is not flux through a leak because it is inhibited by hemicholinium. Influx and efflux show a pronounced exchange flux phenomenon. The ability to concentrate choline is lost when external sodium is replaced by lithium or potassium. However, the uphill movement of choline is probably not coupled directly to the Na+ electrochemical gradient.

Forssman expression on human erythrocytes: biochemical and genetic evidence of a new histo-blood group system

Blood ◽  
2013 ◽  
Vol 121 (8) ◽  
pp. 1459-1468 ◽  
Author(s):  
Lola Svensson ◽  
Annika K. Hult ◽  
Robert Stamps ◽  
Jonas Ångström ◽  
Susann Teneberg ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Group ◽  
Blood Cells ◽  
Human Erythrocytes ◽  
Blood Group System ◽  
Group System ◽  
Glycolipid Antigen ◽  
Human Red Blood Cells ◽  
Key Points ◽  
Forssman Antigen

Key Points A new histo-blood group system was discovered, based on the identification of Forssman glycolipid antigen on human red blood cells. A newly described polymorphism in the GBGT1 gene activates the encoded enzyme to synthesize Forssman antigen.

scholarly journals Transport of uridine in human red blood cells. Demonstration of a simple carrier-mediated process.

1977 ◽  
Vol 69 (1) ◽  
pp. 75-96 ◽  
Author(s):  
Z I Cabantchik ◽  
H Ginsburg
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Human Erythrocytes ◽  
Kinetic Properties ◽  
Kinetic Description ◽  
Human Red Blood Cells ◽  
Methodological Procedures

The kinetic properties of the mediated transport of uridine in human erythrocytes are investigated. Different methodological procedures are use to acquire a complete kinetic description of the system...

scholarly journals Effects of halides and bicarbonate on chloride transport in human red blood cells.

1976 ◽  
Vol 67 (2) ◽  
pp. 223-234 ◽  
Author(s):  
M Dalmark
Keyword(s):  
Red Blood Cells ◽  
Binding Sites ◽  
Blood Cells ◽  
Chloride Transport ◽  
Chloride Concentration ◽  
Human Red Blood Cells ◽  
Half Saturation Constant ◽  
Saturation Kinetics ◽  
Transport Site ◽  
High Chloride

Chloride self-exchange was determined by measuring the rate of 36Cl efflux from human red blood cells at pH 7.2 (0 degrees C) in the presence of fluoride, bromide, iodide, and bicarbonate. The chloride concentration was varied between 10--400 mM and the concentration of other halides and bicarbonate between 10--300 mM. Chloride equilibrium flux showed saturation kinetics. The half-saturation constant increased and the maximum flux decreased in the presence of halides and bicarbonate: the inhibition kinetics were both competitive and noncompetitive. The competitive and the noncompetitive effects increased proportionately in the sequence: fluoride less than bromide less than iodide. The inhibitory action of bicarbonate was predominantly competitive. The noncompetitive effect of chloride (chloride self-inhibition) on chloride transport was less dominant at high inhibitor concentrations. Similarly, the noncompetitive action of the inhibitors was less dominant at high chloride concentrations. The results can be described by a carrier model with two anion binding sites: a transport site, and a second site which modifies the maximum transport rate. Binding to both types of sites increases proportionately in the sequence: fluoride less than chloride less than bromide less than iodide.

scholarly journals Human erythrocytes transport dehydroascorbic acid and sugars using the same transporter complex

2014 ◽  
Vol 306 (10) ◽  
pp. C910-C917 ◽  
Author(s):  
Jay M. Sage ◽  
Anthony Carruthers
Keyword(s):  
Steady State ◽  
Vitamin C ◽  
Blood Cells ◽  
Dehydroascorbic Acid ◽  
Membrane Vesicles ◽  
Human Erythrocytes ◽  
Cytoplasmic Surface ◽  
Glucose Transport Protein ◽  
Inside Out ◽  
Primary Substrate

GLUT1, the primary glucose transport protein in human erythrocytes [red blood cells (RBCs)], also transports oxidized vitamin C [dehydroascorbic acid (DHA)]. A recent study suggests that RBC GLUT1 transports DHA as its primary substrate and that only a subpopulation of GLUT1 transports sugars. This conclusion is based on measurements of cellular glucose and DHA equilibrium spaces, rather than steady-state transport rates. We have characterized RBC transport of DHA and 3- O-methylglucose (3-OMG), a transported, nonmetabolizable sugar. Steady-state 3-OMG and DHA uptake in the absence of intracellular substrate are characterized by similar Vmax (0.16 ± 0.01 and 0.13 ± 0.02 mmol·l−1·min−1, respectively) and apparent Km (1.4 ± 0.2 and 1.6 ± 0.7 mM, respectively). 3-OMG and DHA compete for uptake, with Ki(app) of 0.7 ± 0.4 and 1.1 ± 0.1 mM, respectively. Uptake measurements using RBC inside-out-membrane vesicles demonstrate that 3-OMG and DHA compete at the cytoplasmic surface of the membrane, with Ki(app) of 0.7 ± 0.1 and 0.6 ± 0.1 mM, respectively. Intracellular 3-OMG stimulates unidirectional uptake of 3-OMG and DHA. These findings indicate that DHA and 3-OMG bind at mutually exclusive sites at exo- and endofacial surfaces of GLUT1 and are transported via the same GLUT1 complex.

scholarly journals Furosemide inhibition of chloride transport in human red blood cells.

1976 ◽  
Vol 68 (6) ◽  
pp. 583-599 ◽  
Author(s):  
P C Brazy ◽  
R B Gunn
Keyword(s):  
Transport Mechanism ◽  
Chloride Transport ◽  
Chloride Concentration ◽  
Red Cell Membrane ◽  
Human Red Blood Cells ◽  
Flux Measurements ◽  
Ph Range ◽  
A Site ◽  
Chloride Concentrations ◽  
Human Red Cell Membrane

The chloride self-exchange flux across the human red cell membrane is rapidly and reversibly inhibited by 10(-4) M furosemide, a potent chloruretic agent. Furosemide reduces the chloride flux at all chloride concentrations and increases the cellular chloride concentration at which the flux is half-maximum. Kinetic analysis of the flux measurements made at several furosemide and chloride concentrations yields a pattern of mixed inhibition with a dissociation constant for the inhibitor-transport mechanism complex of 5 X 10(-5) M. From this pattern of inhibition and other observations, including that the percent inhibition is independent of pH (range 5.6-8.9), we conclude that the anionic form of furosemide interacts primarily with the chloride transport mechanism at a site separate from both the transport site and the halide-reactive modifier site.

scholarly journals Kinetics of residual chloride transport in human red blood cells after maximum covalent 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid binding.

1993 ◽  
Vol 101 (5) ◽  
pp. 715-732 ◽  
Author(s):  
P K Gasbjerg ◽  
J Funder ◽  
J Brahm
Keyword(s):  
Red Blood Cells ◽  
Lipid Bilayers ◽  
Blood Cells ◽  
Chloride Transport ◽  
Covalent Binding ◽  
Chloride Concentration ◽  
Disulfonic Acid ◽  
Human Red Blood Cells ◽  
O 19 ◽  
Kinetics Of

Irreversible inhibition, 99.8% of control values for chloride transport in human red blood cells, was obtained by well-established methods of maximum covalent binding of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). The kinetics of the residual chloride transport (0.2%, 106 pmol.cm-2 x s-1) at 38 degrees C, pH 7.2) was studied by means of 36Cl- efflux. The outside apparent affinity, expressed by Ko1/2,c, was 34 mM, as determined by substituting external KCl by sucrose. The residual flux was reversibly inhibited by a reexposure to DIDS, and by 4,4'-dinitrostilbene-2,2'-disulfonate (DNDS), phloretin, salicylate, and alpha-bromo-4-hydroxy-3,5-dinitroacetophenone (Killer III) (Borders, C. L., Jr., D. M. Perez, M. W. Lafferty, A. J. Kondow, J. Brahm, M. B. Fenderson, G. L. Breisford, and V. B. Pett. 1989. Bioorganic Chemistry. 17:96-107), to approximately 0.001% of control cells, which is a flux as low as in lipid bilayers. The reversible DIDS inhibition of the residual chloride flux depended on the extracellular chloride concentration, but was not purely competitive. The half-inhibition concentrations at [Cl(o)] = 150 mM in control cells (Ki,o) and covalently DIDS-treated cells (Ki,c) were: DIDS, Ki,c = 73 nM; DNDS, Ki,o = 6.3 microM, Ki,c = 22 microM; phloretin, Ki,o = 19 microM, Ki,c = 17 microM; salicylate, Ki,o = 4 mM, Ki,c = 8 mM; Killer III, Ki,o = 10 microM, Ki,c = 10 microM.

Passive permeability of human red blood cells to calcium

1986 ◽  
Vol 250 (1) ◽  
pp. C26-C31 ◽  
Author(s):  
M. K. McNamara ◽  
J. S. Wiley
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Human Erythrocytes ◽  
Atp Depletion ◽  
Passive Permeability ◽  
Sodium Potassium ◽  
Human Red Blood Cells ◽  
Order Of Magnitude ◽  
The Difference

Ca2+ influx was measured into human erythrocytes in which efflux was blocked by either introduction of an intracellular Ca2+ chelator, introduction of the Ca2+ chelator followed by ATP depletion, or depletion of the Ca2+ pump cofactors ATP and Mg2+. The Ca2+ influx under all three conditions was 14-20 mumol . 1 cells-1 . h-1, which is an order of magnitude higher than the influx previously reported for cells depleted of either ATP or Mg2+ separately. The difference between the two values was explained by the finding of substantial Ca2+ efflux from the Ca2+-loaded ATP-depleted cells, whereas this efflux was insignificant from cells loaded with quin 2 and then ATP depleted. Under these latter conditions Ca2+ influx estimates the unidirectional permeability to this cation. Studies using this technique showed that Ca2+ influx was the same in media of isotonic sodium, potassium, lithium, choline, or magnesium chlorides. Moreover the dependence of Ca2+ influx on external Ca2+ concentration was well described by the sum of saturable and nonsaturable (linear) components.

Loading of Human Red Blood Cells with DNA and RNA

1976 ◽  
Vol 31 (3-4) ◽  
pp. 149-151 ◽  
Author(s):  
Dieter Auer ◽  
Gerhard Brandner
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Human Erythrocytes ◽  
Viral Dna ◽  
External Concentration ◽  
Dna And Rna ◽  
Human Red Blood Cells ◽  
Hank’S Solution

Abstract Human erythrocytes were suspended in Hank’s solution containing mammalian or viral DNA or RNA. After dialysis at 0 °C first against water and subsequently against Hank’s solution, and a further incubation at 37 °C , the erythrocytes were found to be loaded with the nucleic acids. The nucleic acid trapped in the erythrocytes exhibited up to 35 per cent of the external concentration.

Sign in / Sign up

Export Citation Format

Share Document