scholarly journals Kinetics of Cl-dependent K fluxes in hyposmotically swollen low K sheep erythrocytes.

1991 ◽  
Vol 97 (2) ◽  
pp. 173-193 ◽  
Author(s):  
E Delpire ◽  
P K Lauf
Keyword(s):  
Red Blood Cells ◽  
Kinetic Study ◽  
Kinetic Parameters ◽  
Blood Cells ◽  
Red Cells ◽  
Maximal Velocity ◽  
Temperature Dependent ◽  
Low K ◽  
Kinetics Of ◽  
External K

A detailed kinetic study of K:Cl cotransport in hyposmotically swollen low K sheep red blood cells was carried out to characterize the nature of the outwardly poised carrier. The kinetic parameters were determined from the rate of K efflux and influx under zero-K-trans conditions in red cells with cellular K altered by the nystatin method and with different extracellular K or Rb concentrations. Although apparent affinities for efflux and influx were quite similar, the maximal velocity for K efflux was approximately two times greater than for influx. Furthermore, at thermodynamic equilibrium (i.e., when the ion product of K and Cl within the cell was equal to that outside) a temperature-dependent net K efflux was observed, approaching zero only when the external product reached approximately two times the internal product. The binding order of the ions to the transporter was asymmetric, being ordered outside (Cl binding first, followed by K) and random inside. K efflux but not influx was trans-inhibited by KCl. Trans inhibition of K efflux was used to verify the order of binding outside: trans inhibition by external Cl occurred in the absence of external K, but not vice versa. Thus K:Cl cotransport is kinetically asymmetric in hyposmotically swollen low K sheep red cells.

Kinetics of Na-Li exchange in high and low K sheep red blood cells

1989 ◽  
Vol 257 (1) ◽  
pp. C58-C64 ◽  
Author(s):  
K. H. Ryu ◽  
N. C. Adragna ◽  
P. K. Lauf
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Cell Types ◽  
Sheep Red Blood Cells ◽  
High K ◽  
Ping Pong ◽  
Order Of Magnitude ◽  
Low K ◽  
Kinetics Of ◽  
System Operating

The kinetic parameters and transport mechanism of Na-Li exchange were studied in both low K (LK) and high K (HK) sheep red blood cells with cellular Na [( Na]i) and Li concentrations [( Li]i) adjusted by the nystatin technique (Nature New Biol. 244: 47-49, 1973 and J. Physiol. Lond. 283: 177-196, 1978). Maximum velocities (Vm) for Li fluxes and half-activation constants (K1/2) for Li and Na of the Na-Li exchanger were determined. The K1/2 values for both Li and Na appeared to be similar in both cell types, although they were about two to three times lower on the inside than on the outside of the membrane. Furthermore, the K1/2 values for Li were at least an order of magnitude smaller than those for Na, suggesting substantial affinity differences for these two cations. The Vm values for Li fluxes, on the other hand, appear to be lower in HK than in LK cells. When Na and Li fluxes were measured simultaneously, a trans stimulatory effect by Na on Li fluxes was observed. From measurements of Li influx at different concentrations of external Li and different [Na]i, the ratio of the apparent Vm to the apparent external Li affinity was calculated to be independent of [Na]i for both types of sheep red blood cells. Similar trans effects of external Na were observed on Li efflux at varying [Li]i. These results are expected for a system operating by a “ping-pong” mechanism.

Differentiation of Na(+)-K+ pumps of low-K+ sheep red blood cells is promoted by Lp membrane antigens

1993 ◽  
Vol 265 (1) ◽  
pp. C99-C105 ◽  
Author(s):  
Z. C. Xu ◽  
P. B. Dunham ◽  
B. Dyer ◽  
R. Blostein
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Rat Kidney ◽  
Striking Increase ◽  
Sheep Red Blood Cells ◽  
High K ◽  
Membrane Antigens ◽  
Low K ◽  
Kinetics Of

Na(+)-K+ pumps of red blood cells from sheep of the low-K+ (LK) phenotype undergo differentiation during circulation, manifested in part by a striking increase in sensitivity to inhibition by intracellular K+ (Ki). Pumps of red blood cells from sheep from the allelic phenotype, high K+ (HK), do not undergo this type of maturation. The hypothesis was tested that the Lp antigen, found on LK but not HK cells, is responsible for the maturation of LK pumps. Lp antigens have been shown to inhibit LK pumps because anti-Lp antibody stimulates the pumps by relieving inhibition by the antigen. Lp antigens were recently shown to be molecular entities separate from Na(+)-K+ pumps [Xu, Z.-C., P. Dunham, J. Munzer, J. Silvius, and R. Blostein. Am. J. Physiol. 263 (Cell Physiol. 32): C1007-C1014, 1992]. The test of the hypothesis was to modify the Lp antigens of immature LK red blood cells with two kinds of treatments, anti-Lp antibody and trypsinization (which cleaves Lp), and to observe the effects of these treatments on maturation of pumps during culture of the cells in vitro. Both of these treatments prevented the maturation of the kinetics of the pumps to the Ki-sensitive pattern, supporting the hypothesis that interaction of the pumps with Lp antigens is responsible for the maturation of the pumps. Strong supportive evidence came from experiments on Na(+)-K+ pumps from rat kidney delivered into immature LK sheep red blood cells by microsome fusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of Cl-dependent K influx in human erythrocytes with and without external Na: effect of NEM

1985 ◽  
Vol 249 (5) ◽  
pp. C490-C496 ◽  
Author(s):  
D. Kaji ◽  
T. Kahn
Keyword(s):  
Human Erythrocytes ◽  
Independent Component ◽  
Kinetic Properties ◽  
Maximal Velocity ◽  
Na Effect ◽  
Low K ◽  
Kinetics Of ◽  
K Transport ◽  
Dependent Pathway ◽  
External K

The majority of the ouabain-insensitive K influx in human erythrocytes is dependent on the presence of Cl. Recent studies have shown that a portion of the Cl-dependent K influx persists in the absence of external Na (Nao). It has been suggested that this Nao-independent component represents (K + Cl) cotransport, whereas the remainder of the Cl-dependent K influx seen on addition of external Na represents (Na + K + 2Cl) cotransport. In the present studies, the kinetics of Cl-dependent K influx were examined in the presence and absence of external Na, by varying external K and external Cl. Our studies suggest that the Nao-independent Cl-dependent pathway has a relatively low affinity for external K (Km 17-30 mM) in contrast to the high affinity of the Nao-augmented component (Km 3-4 mM). N-ethylmaleimide (NEM) stimulates the maximal velocity of the Nao-independent Cl-dependent K influx achievable without alteration of intracellular solutes but does not alter its Km for external K. In contrast, NEM has no stimulatory effect on the Nao-augmented component. The Cl dependence of the Nao-independent K influx is best described by a relatively flat curve with a mild upward concavity. The kinetic properties of the Nao-independent component of Cl-dependent K transport are very similar to those of the putative (K + Cl) cotransport pathway seen in low-K sheep erythrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracellular Na+ inhibits Na+/H+ exchange: cell shrinkage reduces the inhibition

2004 ◽  
Vol 287 (2) ◽  
pp. C336-C344 ◽  
Author(s):  
Philip B. Dunham ◽  
Scott J. Kelley ◽  
Paul J. Logue
Keyword(s):  
Growth Factors ◽  
Red Blood Cells ◽  
Cell Volume ◽  
Blood Cells ◽  
Hyperbolic Function ◽  
Maximal Velocity ◽  
Cell Shrinkage ◽  
Inhibitory Site ◽  
Kinetics Of ◽  
In Cells

Na+/H+ exchangers (NHE) are ubiquitous transporters participating in regulation of cell volume and pH. Cell shrinkage, acidification, and growth factors activate NHE by increasing its sensitivity to intracellular H+ concentration. In this study, the kinetics were studied in dog red blood cells of Na+ influx through NHE as a function of external Na+ concentration ([Na+]o). In cells in isotonic media, [Na+]o inhibited Na+ influx >40 mM. Osmotic shrinkage activated NHE by reducing this inhibition. In cells in isotonic media + 120 mM sucrose, there was no inhibition, and influx was a hyperbolic function of [Na+]o. The kinetics of Na+-inhibited Na+ influx were analyzed at various extents of osmotic shrinkage. The curves for inhibited Na+ fluxes were sigmoid, indicating more than one Na+ inhibitory site associated with each transporter. Shrinkage significantly increased the Na+ concentration at half-maximal velocity of Na+-inhibited Na+ influx, the mechanism by which shrinkage activates NHE.

Na-Ca exchange in ferret red blood cells

1989 ◽  
Vol 256 (2) ◽  
pp. C390-C398 ◽  
Author(s):  
M. A. Milanick
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Red Cells ◽  
Ionophore A23187 ◽  
Maximal Velocity ◽  
Free Solution ◽  
Exchange System ◽  
Ca Pump ◽  
Na Efflux ◽  
Intracellular Ca

Ferrets have high Na (140 mmol/l) red blood cells. To determine whether ferret red cells had a Na-Ca exchange system, Na effluxes via the Na + K + 2Cl cotransrpoter and Ca effluxes via the Ca pump had to be inhibited. This was accomplished by replacing cell chloride with nitrate and by loading the cells with vanadate that inhibits the Ca pump. Under these conditions, extracellular Na (Naout) inhibited Ca influx. Intracellular Na (Nain) was required for the large Ca influx as replacement of Na with Li reduced Ca influx to less than one-tenth of the original rate. Caout stimulated Na efflux by about twofold. The Ca efflux from cells depleted of Na was increased from 0.8 to 3.2 mmol.l packed cells-1.h-1 by the presence of Naout. Cells placed in a Na-free solution accumulated Ca: total intracellular Ca was 20-fold higher than free Caout. Most of this Ca was released on addition of the Ca ionophore, A23187. Because the Na gradient had driven net Ca uphill, the fluxes of Na and Ca are coupled. In a Na-free solution, the K1/2 for Ca influx was usually approximately 10 microM (occasionally approximately 100 microM), and the maximal velocity (Vmax was 1.5-4.4 mmol.l packed cells-1.h-1. At Naout = 150 mM, K1/2 increased 5- to 150-fold. In some cells, Naout decreased Vmax by approximately fourfold, suggesting that Naout does not always compete with Caout.(ABSTRACT TRUNCATED AT 250 WORDS)

Electron probe microanalysis of red blood cells. II. Cation changes during maturation

1978 ◽  
Vol 235 (5) ◽  
pp. C251-C255 ◽  
Author(s):  
R. G. Kirk ◽  
P. Lee ◽  
D. C. Tosteson
Keyword(s):  
Stem Cells ◽  
Red Blood Cells ◽  
Electron Probe Microanalysis ◽  
Blood Cells ◽  
Electron Probe ◽  
Bone Marrow Cells ◽  
Red Cells ◽  
Fe Content ◽  
Low K ◽  
Marrow Cells

To understand the sequence of maturation of membrane transport and hemoglobin production during erythropoiesis, we have measured the K, Na, and Fe content in single mature red blood cells and bone marrow cells of dog using electron probe microanalysis (EPMA). Mature red blood cells of dog are low in potassium (LK) and high in sodium. These cells are derived from erythroblastic stem cells, which are high in potassium (HK) and low in sodium. This change from HK stem cells to LK red cells occurs in the marrow. The ratio of K/Na was found to be less than 0.2 independent of Fe/(K + Na) in circulating red cells. However, a significant number of marrow cells had both low K/Na and low Fe/(K + Na). We conclude that the changes in cation transport properties responsible for the conversion of HK to LK cells occur before the synthesis of hemoglobin in at least some marrow cells.

HEMOLYTIC DISEASE OF THE NEWBORN DUE TO ANTI-A AND ANTI-B

PEDIATRICS ◽  
1955 ◽  
Vol 15 (1) ◽  
pp. 54-62
Author(s):  
Clare N. Shumway ◽  
Gerald Miller ◽  
Lawrence E. Young
Keyword(s):  
B Cells ◽  
Red Blood Cells ◽  
Blood Group ◽  
Newborn Infant ◽  
Blood Cells ◽  
Osmotic Fragility ◽  
Red Cells ◽  
Hemolytic Disease ◽  
Abo Incompatibility

Ten infants with hemolytic disease of the newborn due to ABO incompatibility were studied. In every case the investigations were undertaken because of jaundice occurring in the first 24 hours of life. The clinical, hematologic and serologic observations in the infants and the serologic findings in the maternal sera are described. Evidence is presented to show that the diagnosis of the disorder rests largely upon the demonstration of spherocytosis, increased osmotic fragility of the red cells, reticulocytosis, and hyperbilirubinemia in a newborn infant whose red blood cells are incompatible with the maternal major blood group isoantibody and against whose cells no other maternal isoantibody is demonstrable. The anti-A or anti-B in each of the maternal sera tested in this series hemolyzed A or B cells in the presence of complement. Other serologic findings in the maternal sera were less consistently demonstrated.

scholarly journals Sensing of red blood cells with decreased membrane deformability by the human spleen

2018 ◽  
Vol 2 (20) ◽  
pp. 2581-2587 ◽  
Author(s):  
Innocent Safeukui ◽  
Pierre A. Buffet ◽  
Guillaume Deplaine ◽  
Sylvie Perrot ◽  
Valentine Brousse ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Ex Vivo ◽  
Volume Ratio ◽  
Red Cells ◽  
Human Spleen ◽  
Rbc Membrane ◽  
Membrane Rigidity ◽  
Cellular Deformability ◽  
Distinct Features

Abstract The current paradigm in the pathogenesis of several hemolytic red blood cell disorders is that reduced cellular deformability is a key determinant of splenic sequestration of affected red cells. Three distinct features regulate cellular deformability: membrane deformability, surface area-to-volume ratio (cell sphericity), and cytoplasmic viscosity. By perfusing normal human spleens ex vivo, we had previously showed that red cells with increased sphericity are rapidly sequestered by the spleen. Here, we assessed the retention kinetics of red cells with decreased membrane deformability but without marked shape changes. A controlled decrease in membrane deformability (increased membrane rigidity) was induced by treating normal red cells with increasing concentrations of diamide. Following perfusion, diamide-treated red blood cells (RBCs) were rapidly retained in the spleen with a mean clearance half-time of 5.9 minutes (range, 4.0-13.0). Splenic clearance correlated positively with increased membrane rigidity (r = 0.93; P < .0001). To determine to what extent this increased retention was related to mechanical blockade in the spleen, diamide-treated red cells were filtered through microsphere layers that mimic the mechanical sensing of red cells by the spleen. Diamide-treated red cells were retained in the microsphilters (median, 7.5%; range, 0%-38.6%), although to a lesser extent compared with the spleen (median, 44.1%; range, 7.3%-64.0%; P < .0001). Taken together, these results have implications for understanding the sensitivity of the human spleen to sequester red cells with altered cellular deformability due to various cellular alterations and for explaining clinical heterogeneity of RBC membrane disorders.

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