Inhibition of the phosphate self-exchange flux in human erythrocytes and erythrocyte ghosts

1990 ◽  
Vol 118 (1) ◽  
pp. 19-47 ◽  
Author(s):  
F. Stadler ◽  
K. F. Schnell
Keyword(s):  
Human Erythrocytes ◽  
Erythrocyte Ghosts ◽  
Exchange Flux

Lead and calcium transport in human erythrocyte

1999 ◽  
Vol 18 (5) ◽  
pp. 327-332 ◽  
Author(s):  
J V Calderón-Salinas ◽  
M A Quintanar-Escorcia ◽  
M T González-Martínez ◽  
C E Hernández-Luna
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Calcium Transport ◽  
Human Erythrocytes ◽  
The Other ◽  
Erythrocyte Ghosts ◽  
Passive Transport ◽  
Ca Uptake

In this paper we report the lead (Pb) and calcium (Ca) uptake by erythrocyte ghosts. In both cases the transport was carried out by a passive transport system with two kinetic components (Michaelis-Menten and Hill). Pb and Ca were capable of inhibiting the transport of the other metal in a non-competitive way. Under hyperpolarization, the uptakes of Ca and Pb were enhanced and the Michaelis-Menten component prevailed. Both Ca and Pb uptakes were inhibited by N-ethyl-maleimide to the same extent. These results indicate that Pb and Ca share the same permeability pathway in human erythrocytes and that this transport system is electrogenic.

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.

scholarly journals Evidence that the uptake of tri-iodo-l-thyronine by human erythrocytes is carrier-mediated but not energy-dependent

1982 ◽  
Vol 208 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Roelof Docter ◽  
Eric P. Krenning ◽  
Greetje Bos ◽  
Durk F. Fekkes ◽  
George Hennemann
Keyword(s):  
Contrast Agents ◽  
Rat Hepatocytes ◽  
Human Erythrocytes ◽  
Uptake System ◽  
Erythrocyte Ghosts ◽  
Intact Cells ◽  
X Ray ◽  
Dose Dependent Fashion ◽  
Uptake Studies ◽  
Energy Dependent

We investigated 3,3′,5-tri-iodo-l-thyronine transport by human erythrocytes and by ‘ghosts’ prepared from these cells. Uptake of tri-iodothyronine by erythrocytes at 37°C was time-dependent with a maximum reached after 60min. Tracer analysis after incubation for 1min revealed only one saturable binding site, with Km 128±19nm (mean±s.e.m.; n=7) and Vmax. 4.6±0.7pmol of tri-iodothyronine/min per 6×107 cells. After 10min incubation Km 100±16nm (n=10) was found with Vmax. 7.7±1.2pmol of tri-iodothyronine/10min per 6×107 cells. At 0°C the uptake system is still active, with Km 132±26nm and Vmax. 1.8±0.3pmol of tri-iodothyronine/10min per 6×107 cells. The Vmax. with intact cells is 5-fold greater than the Vmax. with membranes derived from the same amount of cells when uptake studies are performed in media with similar free tri-iodothyronine concentrations. This indicates that at least 80% of tri-iodothyronine taken up by the intact erythrocytes enters the cell. This saturable uptake system can be inhibited by X-ray-contrast agents in a dose-dependent fashion. (±)-Propranolol, but not atenolol, has the same effect, indicating that the membrane-stabilizing properties of (±)-propranolol are involved. Furthermore, there is no inhibition by ouabain or vanadate, which indicates that tri-iodothyronine uptake is not dependent on the activity of Na++K+-dependent adenosine triphosphatase. We have prepared erythrocyte ‘ghosts‘, resealed after 2.5min with 0mm-, 2mm- or 4mm-ATP inside. Inclusion of ATP and integrity of the membrane of the erythrocyte ‘ghosts’ were verified on the basis of an ATP-concentration-dependent functioning of the Ca2+ pump. No difference was found in the uptake of tri-iodothyronine by erythrocyte ‘ghosts’ with or without ATP included, indicating that uptake of tri-iodothyronine is not ATP-dependent. The following conclusions are drawn. (1) Tri-iodothyronine enters human erythrocytes. (2) There is only one saturable uptake system present for tri-iodothyronine, which is neither energy (i.e. ATP)-dependent nor influenced by the absence of an Na+ gradient across the plasma membrane. This mode of uptake of tri-iodothyronine by human erythrocytes is in sharp contrast with that of rat hepatocytes, which uptake system is energy-dependent and ouabain-sensitive [Krenning, Docter, Bernard, Visser & Hennemann (1978) FEBS Lett.91, 113–116; Krenning, Docter, Bernard, Visser & Hennemann (1980) FEBS Lett.119, 279–282]. (3) X-ray-contrast agents inhibit tri-iodothyronine uptake by erythrocytes in a similar fashion to that by which they inhibit the uptake of tri-iodothyronine by rat hepatocytes [Krenning, Docter, Bernard, Visser & Hennemann (1982) FEBS Lett.140, 229–233].

The effect of (13 OOH) linoleic acid on human erythrocytes and on erythrocyte ghosts

1983 ◽  
Vol 754 (3) ◽  
pp. 238-242 ◽  
Author(s):  
J.F. Koster ◽  
R.G. Slee ◽  
C.C.M.Rutten-Van Beysterveld ◽  
A. Montfoort
Keyword(s):  
Linoleic Acid ◽  
Human Erythrocytes ◽  
Erythrocyte Ghosts

scholarly journals The effects of Ca2+ and Sr2+ on Ca2+-sensitive biochemical changes in human erythrocytes and their membranes

1981 ◽  
Vol 198 (3) ◽  
pp. 441-445 ◽  
Author(s):  
D Allan ◽  
P Thomas
Keyword(s):  
Direct Interaction ◽  
Human Erythrocytes ◽  
Biochemical Changes ◽  
Intracellular Concentration ◽  
Ionophore A23187 ◽  
Erythrocyte Ghosts ◽  
High Concentration ◽  
Intact Cells ◽  
Whole Cells

1. The Ca2+-dependency of K+ efflux, microvesiculation and breakdown of polyphosphoinositides and of ankyrin have been measured in intact human erythrocytes exposed to ionophore A23187 and HEDTA [N'-(2-hydroxyethyl)ethylenediamine NNN'-triacetate]-Ca2+ buffers. Half-maximal responses were observed at pCa values of 6.4, 4.1, 5.0 and 4.8 respectively. 2. The Ca2+ dependencies of K+ efflux and breakdown of polyphosphoinositides and ankyrin measured in erythrocyte ghosts without addition of ionophore showed almost identical values with those seen in whole cells treated with ionophore. 3. We conclude that ionophore A23187 is able to cause rapid equilibration of extracellular and intracellular [Ca2+] in intact cells and that in the presence of a suitable Ca2+ buffer, ionophore A23187 can be used to precisely fix the intracellular concentration of Ca2+ in erythrocytes. 4. The relatively high concentration of Ca2+ required to produce microvesiculation in intact cells may indicate that microvesiculation could be at least partly dependent on a direct interaction of Ca2+ with phospholipid. 5. Results obtained with Sr2+ paralleled those with Ca2+, although higher Sr2+ concentrations were required to achieve the same effects as Ca2+. Mg2+ produced none of the changes seen with Ca2+ or Sr2+.

STAPHYLOCOCCAL TOXINS: II. FACTORS AFFECTING HEMOLYSIS BY δ-LYSIN

1958 ◽  
Vol 4 (5) ◽  
pp. 435-444 ◽  
Author(s):  
A. W. Jackson ◽  
R. M. Little
Keyword(s):  
Human Erythrocytes ◽  
Magnesium Ions ◽  
Erythrocyte Ghosts ◽  
Factors Affecting ◽  
Early Stages

The influence of a number of variables upon lysis of erythrocytes by staphylococcal δ-lysin has been examined. Hemolysis of human erythrocytes by δ-lysin has been found to be unaffected by the presence of α-lysin but is inhibited by a number of proteins, serum being the most active of those tested. Glucose, citrate, and magnesium ions were found to have no effect on hemolysis by δ-lysin. Hemoglobin and erythrocyte ghosts were inhibitory. Release of cell constituents during hemolysis is considered to be partly responsible for the change from a rapid to a slower rate of hemolysis in the early stages of the reaction.It was found that the extent of hemolysis of a 1% suspension of human erythrocytes is linearly related to lysin concentration provided lysis is not greater than 65% nor less than 30% of total hemolysis. A method of determining relative δ-lysin activity is described.

The Feeding Response of Rhodnius Prolixus to Blood Fractions, and the Role of ATP

1979 ◽  
Vol 78 (1) ◽  
pp. 225-232
Author(s):  
J.B. J. SMITH
Keyword(s):  
Adenosine Triphosphate ◽  
Rhodnius Prolixus ◽  
Human Erythrocytes ◽  
Erythrocyte Ghosts ◽  
Feeding Response ◽  
Sense Organs

Second-instar larvae of Rhodnius prolixus will gorge on washed human erythrocytes suspended in Ringer, but not on plasma, either with or without platelets. The ED 50 of erythrocytes is 4.5 vol of packed cells per 1000 vol of Ringer. Erythrocyte ‘ghosts’ are non-stimulatory, whereas the haemolysate induces gorging. Phagostimulation by ‘ghosts’ is restored by resealing them in 1 mM adenosine triphosphate. Evidence is presented that Rhodnius responds to blood via a release of ATP from a few erythrocytes close to the epipharyngeal sense organs.

Shape transformation of erythrocyte ghosts depends on ion concentrations

1985 ◽  
Vol 5 (5) ◽  
pp. 417-423 ◽  
Author(s):  
Andreas Herrmann ◽  
Peter Müller ◽  
Roland Glaser
Keyword(s):  
Human Erythrocyte ◽  
Transmembrane Potential ◽  
Human Erythrocytes ◽  
Erythrocyte Ghosts ◽  
Shape Transformation ◽  
Ion Concentrations ◽  
Nacl Concentration ◽  
Shape Transformations

Resealed human erythrocyte ghosts undergo shape transformations similar to those of intact erythrocytes. The results indicate that the shape of these ghosts depends on the inner as well as on the outer NaCl concentration. A correlation between shape and calculated transmembrane potential was established similar to that for intact human erythrocytes.

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