scholarly journals Anion inhibitor-sensitive unidirectional sodium movements in the human erythrocyte.

1978 ◽  
Vol 72 (1) ◽  
pp. 87-100 ◽  
Author(s):  
T J Callahan ◽  
D A Goldstein
Keyword(s):  
Human Erythrocyte ◽  
Anion Transport ◽  
Ion Pair ◽  
Chloride Ions ◽  
Human Erythrocytes ◽  
Disulfonic Acid ◽  
Salt Solutions ◽  
Sodium Influx ◽  
Bicarbonate Ions ◽  
Additional Assumptions

The increased unidirectional sodium influx found when human erythrocytes are suspended in isotonic salt solutions containing bicarbonate ions as a replacement for chloride ions was examined. The increased sodium movement appears to have the transport characteristics of anion movement. Inhibitors of anion transport such as furosemide, fluorodinitrobenzene (FDNB), and 4-acetamido-4'-isothiocyano-stilbene-2-2'-disulfonic acid (SITS) drastically inhibit these augmented sodium movements. An ion-pair mechanism appears to phenomenologically describe much of the data. A possible role for carbamino groups is considered. Such a model, however, required additional assumptions to explain the selectivity and the anion inhibitor effects.

Elemental analysis of human erythrocytes

1989 ◽  
Vol 47 ◽  
pp. 242-243
Author(s):  
S. A. Livesey ◽  
A. A. del Campo ◽  
E. S. Griffey ◽  
D. Ohlmer ◽  
T. Schifani ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Elemental Analysis ◽  
Human Erythrocyte ◽  
Spectroscopic Analysis ◽  
Model System ◽  
Human Erythrocytes ◽  
List Type ◽  
Chemical Fixation ◽  
Ethanol Dehydration ◽  
Lowicryl K4m

The aim of this study is to compare methods of sample preparation for elemental analysis. The model system which is used is the human erythrocyte. Energy dispersive spectroscopic analysis has been previously reported for cryofixed and cryosectioned erythrocytes. Such work represents the reference point for this study. The use of plastic embedded samples for elemental analysis has also been documented. The work which is presented here is based on human erythrocytes which have been either chemically fixed and embedded or cryofixed and subsequently processed by a variety of techniques which culminated in plastic embedded samples.Heparinized and washed erythrocytes were prepared by the following methods for this study :(1). Chemical fixation in 4% paraformaldehyde/0.25% glutaraldehyde/0.2 M sucrose in 0.1 M Na cacodylate, pH 7.3 for 30 min, followed by ethanol dehydration, infiltration and embedding in Lowicryl K4M at -20° C.

scholarly journals Changes in the Membrane Permeability of Frog's Sartorius Muscle Fibers in Ca-Free EDTA Solution

1963 ◽  
Vol 47 (2) ◽  
pp. 379-392 ◽  
Author(s):  
H. Kimizuka ◽  
K. Koketsu
Keyword(s):  
Membrane Permeability ◽  
Chloride Content ◽  
Chloride Ions ◽  
Sartorius Muscle ◽  
Constant Field ◽  
Sodium Influx ◽  
Sodium Potassium ◽  
Edta Solution ◽  
Frog Sartorius ◽  
Sodium And Potassium

The changes in the membrane permeability to sodium, potassium, and chloride ions as well as the changes in the intracellular concentration of these ions were studied on frog sartorius muscles in Ca-free EDTA solution. It was found that the rate constants for potassium and chloride efflux became almost constant within 10 minutes in the absence of external calcium ions, that for potassium increasing to 1.5 to 2 times normal and that for chloride decreasing about one-half. The sodium influx in Ca-free EDTA solution, between 30 and 40 minutes, was about 4 times that in Ringer's solution. The intracellular sodium and potassium contents did not change appreciably but the intracellular chloride content had increased to about 4 times normal after 40 minutes. By applying the constant field theory to these results, it was concluded that (a) PCl did not change appreciably whereas PK decreased to a level that, in the interval between 10 and 40 minutes, was about one-half normal, (b) PNa increased until between 30 and 40 minutes it was about 8 times normal. The low value of the membrane potential between 30 and 40 minutes was explained in terms of the changes in the membrane permeability and the intracellular ion concentrations. The mechanism for membrane depolarization in this solution was briefly discussed.

Conformation and stability of the anion transport protein of human erythrocyte membranes

Biochemistry ◽  
1985 ◽  
Vol 24 (12) ◽  
pp. 2843-2848 ◽  
Author(s):  
Kimio Oikawa ◽  
Debra M. Lieberman ◽  
Reinhart A. F. Reithmeier
Keyword(s):  
Human Erythrocyte ◽  
Anion Transport ◽  
Transport Protein ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membranes

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 A carbohydrate-deficient membrane glycoprotein in human erythrocytes of phenotype S-s-

1977 ◽  
Vol 165 (1) ◽  
pp. 157-161 ◽  
Author(s):  
M J A Tanner ◽  
D J Anstee ◽  
P A Judson
Keyword(s):  
Blood Group ◽  
Arachis Hypogaea ◽  
Human Erythrocyte ◽  
Structure And Function ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Membrane Glycoprotein ◽  
Blood Group Antigens ◽  
And Function ◽  
Normal Erythrocyte

1. We investigated the membranes of human erythrocytes which completely lack the blood-group antigens S and s (denoted as S-s-) as part of a study of the structure and function of the surface glycoproteins of the human erythrocyte. 2. The S-s-erythrocyte-membrane glycoprotein PAS-3 band was much less intensely stained in comparison with that of the glycoprotein from normal erythrocyte membranes. The S-s-membrane glycoprotein PAS-4 band also showed decreased staining. 3. Examination with the lectins from Maclura aurantiaca (Osage orange) and Arachis hypogaea (groundnut) showed that the PAS-3 glycoprotein of S-s-erythrocyte membranes lacked the receptors for these lectins that are present on glycoprotein PAS-3 from normal erythrocytes. 4. Radioiodination with lactoperoxidase showed the presence of the polypeptide of glycoprotein PAS-3 in S-s-cells, although it was more weakly labelled than the protein in the normal erythrocyte. 5. Our results show that the PAS-3 glycoprotein of S-s-erythrocytes is deficient in some of the carbohydrates present in the protein from normal erythrocytes. Glycoprotein PAS-4 of normal erythrocytes is shown to be a complex containing both glycoproteins PAS-1 and PAS-3.

Kinetics of reversible DIDS inhibition of chloride self exchange in human erythrocytes

1989 ◽  
Vol 257 (4) ◽  
pp. C601-C606 ◽  
Author(s):  
T. Janas ◽  
P. J. Bjerrum ◽  
J. Brahm ◽  
J. O. Wieth
Keyword(s):  
Transport System ◽  
Time Course ◽  
Order Rate Constant ◽  
Anion Transport ◽  
Disulfonic Acid ◽  
Reversible Inhibitor ◽  
Apparent Dissociation Constant ◽  
Anion Transport System ◽  
Relative Change ◽  
Kinetics Of

The capnophorin (band 3)-mediated chloride self exchange flux in intact erythrocytes and in resealed erythrocyte ghosts was determined at pH 7.3 by measuring the unidirectional efflux of 36Cl-. The time-dependent irreversible inactivation of the anion transport system by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) was measured as the relative change of the unidirectional 36Cl efflux rate. The rate of covalent DIDS binding under conditions of excess DIDS in solution that ensure a complete irreversible inhibition followed an exponential time course with a rate coefficient Kcov (min-1). The Arrhenius activation enthalpy of Kcov was constant, 114 kJ/mol, at 0-38 degrees C. At 38 and 0 degrees C, Kcov was 0.5 min-1 [half time (T1/2) = ln2/Kcov = 1.3 min] and 0.004 min-1 (T1/2 = 178 min), respectively. The slow irreversible DIDS binding to the anion transport system at 0 degrees C allows a determination of the kinetics of the reversible DIDS reaction. The pseudo first-order rate constant for binding, kon, was 3.5 X 10(5) (M.s)-1. The apparent dissociation constant, KD, determined from the steady-state binding to the erythrocyte membrane was 3.1 X 10(-8) M at an equal internal and external Cl- concentration of 165 mM (0 degrees C). The value of KD shows that DIDS is the most efficient reversible inhibitor among the stilbene derivatives so far studied. Maximum reversible inhibition by DIDS was obtained by binding of a minimum of approximately 10(6) molecules/cell membrane. The number is similar to that obtained from studies of irreversible DIDS binding.

scholarly journals Faropenem Transport across the Renal Epithelial Luminal Membrane via Inorganic Phosphate Transporter Npt1

2000 ◽  
Vol 44 (3) ◽  
pp. 574-577 ◽  
Author(s):  
Hiroshi Uchino ◽  
Ikumi Tamai ◽  
Hikaru Yabuuchi ◽  
Kayoko China ◽  
Ken-ichi Miyamoto ◽  
...  
Keyword(s):  
Inorganic Phosphate ◽  
Expression System ◽  
Mevalonic Acid ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Phosphate Transporter ◽  
Disulfonic Acid ◽  
Renal Secretion ◽  
Luminal Membrane ◽  
Anionic Drugs

ABSTRACT We previously showed that the mouse inorganic phosphate transporter Npt1 operates in the hepatic sinusoidal membrane transport of anionic drugs such as benzylpenicillin and mevalonic acid. In the present study, the mechanism of renal secretion of penem antibiotics was examined by using a Xenopus oocyte expression system. Faropenem (an oral penem antibiotic) was transported via Npt1 with a Michaelis-Menten constant of 0.77 ± 0.34 mM in a sodium-independent but chloride ion-sensitive manner. When the concentration of chloride ions was increased, the transport activity of faropenem by Npt1 was decreased. Since the concentration gradient of chloride ions is in the lumen-to-intracellular direction, faropenem is expected to be transported from inside proximal tubular cells to the lumen. So, we tested the release of faropenem from Xenopusoocytes. The rate of efflux of faropenem from Npt1-expressing oocytes was about 9.5 times faster than that from control water-injectedXenopus oocytes. Faropenem transport by Npt1 was significantly inhibited by β-lactam antibiotics such as benzylpenicillin, ampicillin, cephalexin, and cefazolin to 24.9, 40.5, 54.4, and 26.2% of that for the control, respectively. Zwitterionic β-lactam antibiotics showed lesser inhibitory effects on faropenem uptake than anionic derivatives, indicating that Npt1 preferentially transports anionic compounds. Other anionic compounds, such as indomethacin and furosemide, and the anion transport inhibitor 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid significantly inhibited faropenem uptake mediated by Npt1. In conclusion, our results suggest that Npt1 participates in the renal secretion of penem antibiotics.

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