Voltage-activated cation permeability in high-potassium but not low-potassium red blood cells

1990 ◽  
Vol 258 (6) ◽  
pp. C1169-C1172 ◽  
Author(s):  
J. A. Halperin ◽  
C. Brugnara ◽  
T. Van Ha ◽  
D. C. Tosteson
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Dielectric Breakdown ◽  
Cation Transport ◽  
Membrane Component ◽  
Transport Pathway ◽  
High Potassium ◽  
Human Red Blood Cells ◽  
Cation Permeability ◽  
Low Potassium

We have recently reported that voltage-activated fluxes of Na, K, and Ca occur in human red blood cells [J.A. Halperin, C. Brugnara, M. Tosteson, T. Van Ha, and D. C. Tosteson. Am. J. Physiol. 257 (Cell Physiol. 26): C986-C996, 1989]. The cation permeability increases progressively as the membrane potential becomes more inside positive above +20 mV. In this paper we show that this effect also occurs in high-potassium (HK), but not in low-potassium (LK), sheep and dog red blood cells. This result suggests that the voltage-activated cation transport pathway is not the result of nonspecific dielectric breakdown of the lipid bilayer but, rather, relates to some membrane component, presumably a protein, that is expressed in HK human and sheep but not in LK sheep and dog red blood cells.

scholarly journals Interaction of HK and LK Goat Red Blood Cells with Ouabain

1974 ◽  
Vol 64 (5) ◽  
pp. 536-550 ◽  
Author(s):  
John R. Sachs ◽  
Philip B. Dunham ◽  
Donna L. Kropp ◽  
J. Clive Ellory ◽  
Joseph F. Hoffman
Keyword(s):  
Red Blood Cells ◽  
Binding Sites ◽  
Blood Cells ◽  
Red Cells ◽  
Ouabain Binding ◽  
High Potassium ◽  
Considerable Heterogeneity ◽  
Low Potassium ◽  
The Difference ◽  
Calculated Number

The characteristics of the interaction of Na-K pumps of high potassium (HK) and low potassium (LK) goat red blood cells with ouabain have been determined. The rate of inhibition by ouabain of the pump of HK cells is greater than the rate of inhibition of the pumps of LK cells. Treatment of LK cells with an antibody (anti-L) raised in HK sheep by injecting LK sheep red cells increases the rate of inhibition of the LK pumps by ouabain to that characteristic of HK pumps; reduction of intracellular K (Kc) in LK cells increases the rate at which ouabain inhibits their pumps and exposure of these low Kc cells to anti-L does not affect the rate of inhibition. There is considerable heterogeneity in the pumps of both HK and LK cells in the rate at which they interact with ouabain or the rate at which they pump or both. LK pumps which are sensitive to stimulation by anti-L bind ouabain less rapidly than the remainder of the LK pumps and exposure to antibody increases the rate at which ouabain binds to the sensitive pumps; the difference between the two types of pumps disappears if intracellular K is very low. The calculated number of ouabain molecules bound at 100% inhibition of the pump is about the same for HK and LK cells. Although exposure to anti-L increases the apparent number of ouabain binding sites in LK cells at normal Kc, it does not alter the apparent number of sites in LK cells when Kc has been reduced.

Insulin sensitivity of human red blood cells cation transport

1985 ◽  
Vol 10 ◽  
pp. 26-29 ◽  
Author(s):  
P. Baldini ◽  
M. D'Onofrio ◽  
S. Incerpi ◽  
P. Luly ◽  
C. Rinaldi ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Cation Transport ◽  
Human Red Blood Cells

scholarly journals Antibody-Induced Alterations in the Kinetic Characteristics of the Na:K Pump in Goat Red Blood Cells

1974 ◽  
Vol 63 (4) ◽  
pp. 389-414 ◽  
Author(s):  
John R. Sachs ◽  
J. Clive Ellory ◽  
Donna L. Kropp ◽  
Philip B. Dunham ◽  
Joseph F. Hoffman
Keyword(s):  
Red Blood Cells ◽  
Outer Surface ◽  
Blood Cells ◽  
Red Cells ◽  
Kinetic Characteristics ◽  
High Potassium ◽  
Low Concentrations ◽  
Pump Rate ◽  
Inner Surface ◽  
Low Potassium

The kinetic characteristics of the Na:K pump in high potassium (HK) and low potassium (LK) goat red cells were investigated after altering the intracellular cation concentrations. At low concentrations of intracellular K (Kc), increasing Kc at first stimulates the active K influx in HK cells, but at higher Kc the pump is inhibited. These results suggest that in HK cells Kc acts both at a stimulatory site at the inner aspect of the pump and by competition with intracellular Na (Nac) at the Na translocation sites. In LK cells, Kc inhibits the active K influx and the sensitivity of LK cells to inhibition is much greater than the sensitivity of HK cells. Exposure of LK cells to an antibody (anti-L), raised in an HK sheep by injection of LK sheep cells, increased the active K influx at any given Kc. The effect of the antibody was greater at higher intracellular K concentrations, and in cells with very low concentrations of K the antibody had little effect on the pump rate. The failure of anti-L to stimulate the pump in low Kc LK cells was not due to failure of the antibody to bind to the cells. Anti-L combining at the outer surface of the cell reduces the affinity of the pump at the inner surface for K at the inhibitory sites. The maximal pump rate in LK cells at optimal Na and K concentrations is less than the maximal pump rate of HK cells under the same circumstances.

Calcium, cell shrinkage, and prolytic state of human red blood cells

1987 ◽  
Vol 252 (2) ◽  
pp. C138-C152 ◽  
Author(s):  
L. M. Crespo ◽  
T. S. Novak ◽  
J. C. Freedman
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Major Effect ◽  
Ionophore A23187 ◽  
Cell Shrinkage ◽  
Human Red Blood Cells ◽  
Na Permeability ◽  
Cation Permeability ◽  
High K ◽  
Indirect Consequence

The effects of intracellular calcium, or Cac, on the Na permeability of human red blood cells were examined during 3-h incubations with the Ca ionophore A23187 and varied external Ca, Cao. Above 3 microM Cao, Nac increased significantly as ATP decreased. Maintenance of normal ATP with vanadate did not prevent the gain of Nac. Similar amounts of Nac were gained in 3 h by ouabain-treated cells exposed to the K ionophore valinomycin or by cells osmotically shrunken. Cells shrunken with sucrose also exhibited partial loss of Kc. When the cells with increased Nac were subsequently transferred to Na-free, high-K medium, the Nac and Kc that had changed slowly over 3 h returned toward normal within 10 min. The development of irreversible high cation permeability in shrunken cells was not prevented by a variety of transport inhibitors. These observations and cell volume distributions suggest that prolonged shrinkage induces a subpopulation of cells to become highly cation permeable, or "prolytic". The major effect of Cac on Na permeability appears to be an indirect consequence of cell shrinkage due to KCl loss.

Electron probe microanalysis of red blood cells. I. Methods and evaluation

1978 ◽  
Vol 235 (5) ◽  
pp. C245-C250 ◽  
Author(s):  
R. G. Kirk ◽  
C. Bronner ◽  
W. Barba ◽  
D. C. Tosteson
Keyword(s):  
Red Blood Cells ◽  
Electron Probe Microanalysis ◽  
Blood Cells ◽  
Electron Probe ◽  
Freeze Drying ◽  
Pyrolytic Graphite ◽  
High Potassium ◽  
Spray Technique ◽  
Low Potassium ◽  
Cell Volumes

The concentrations of potassium, sodium, and iron in human and sheep red blood cells were measured with an electron probe. Cells were prepared for analysis by spraying them on pyrolytic graphite supports. The results obtainedwith this spray technique agreed well with values measured on similar cells that were prepared for analysis by freezing, sectioning, and freeze-drying. Higher Na concentrations and lower K concentrations were found to be associated with lower cell volumes in human and high-potassium sheep cells. In low-potassium sheep cells the reverse was found, lower Na and higher K concentrations were associated with lower cell volumes. However, the amounts of iron were found to remain relatively constant in all human cells.

Changes in the cation composition and active K+ transport in the red cells of fetal sheep prepartum

1985 ◽  
Vol 63 (11) ◽  
pp. 1454-1459
Author(s):  
M. W. Wolowyk ◽  
J. C. Ellory
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Sodium Pump ◽  
Red Cells ◽  
Ouabain Binding ◽  
High Potassium ◽  
Fetal Sheep ◽  
Sodium Pumps ◽  
Low Potassium ◽  
Pump Activity

The red blood cells of lambs, genotypically low potassium type, undergo a transition from high potassium to low potassium cell type from parturition onwards. This involves gradual changes in cell ion content, sodium pump activity, and ouabain binding. In the present study we investigated the properties of fetal red blood cells from 30 days prepartum using the chronically cannulated pregnant ewe preparation. We demonstrate that intracellular sodium increases and potassium decreases from −30 days onwards. Sodium pump activity monitored either by tracer potassium influx or ouabain binding is markedly higher in the early fetal samples examined and declines fourfold during the final month in utero. Unlike the maternal low potassium cells the early fetal red cells are refractory in terms of sodium pump stimulation by anti-L, the antibody in fact consistently inhibiting the pump. Finally, we have investigated the volume sensitivity and development of the ouabain-insensitive potassium fluxes in these cells and found that both fetal and maternal cells show a marked chloride-dependent, volume-sensitive passive potassium flux. We conclude that the decrease in active sodium transport between fetal red cells and adult low potassium cells is achieved partly by a reduction in the density of sodium pumps per cell, and then later by the introduction into the circulation of cells with Lp-antigen-modified sodium pumps.

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