Calcium-induced transient potassium efflux in human red blood cells

1986 ◽  
Vol 250 (1) ◽  
pp. C55-C64 ◽  
Author(s):  
J. S. Adorante ◽  
R. I. Macey
Keyword(s):  
Ionic Strength ◽  
Phase I ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Potassium Efflux ◽  
Pump Failure ◽  
Human Red Blood Cells ◽  
Low Ionic Strength ◽  
Low K ◽  
Phase Phase

Human red blood cells pretreated with low-ionic-strength solutions and resuspended in saline respond biphasically to extracellular Ca. At first, addition of Ca causes a large transient K efflux of as much as 600 mM . liter cell H2O-1 . h-1; this is followed by a decrease in K flux below control levels. The first phase (phase I) resembles the Gardos effect in several respects. It is inhibited by oligomycin, by external K, and by increased exposure time to Ca. Further, the K permeability of phase I is similar to that of the Gardos effect (5 X 10(-8)-9 X 10(-8) cm/s), and the cells hyperpolarize in a low-K medium when Ca2+ is added. However, phase I is not identical to the Gardos phenomenon. For example, La, which prevents the Gardos response, is ineffective on phase I. Moreover, external Ba prevents the development of phase I but not the Gardos response, whereas internal Ba prevents the Gardos response. Attempts to demonstrate a Ca leak or pump failure during phase I have failed; passive Ca movements of both treated and normal cells are similar. The results suggest that low-ionic-strength solution exposes Ca-sensitive sites to the external medium; these sites are maintained when the cells are returned to saline.

scholarly journals A Hundred-Year Researching History on the Low Ionic Strength in Red Blood Cells: Literature Review

2021 ◽  
Vol 2 (3) ◽  
pp. 139-168
Author(s):  
GF Fuhrmann ◽  
KJ Netter
Keyword(s):  
Membrane Potential ◽  
Ionic Strength ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Sucrose Solution ◽  
Critical Survey ◽  
Unequal Distribution ◽  
Donnan Equilibrium ◽  
Disulfonic Stilbene ◽  
Low Ionic Strength

This review article provides a critical survey of work from 1904 to 2003 on the effects of low ionic strength in Red Blood Cells (RBCs) incubated in media with impermeable sugars such as sucrose. In 1904 Gürber A washed RBCs of different species with isotonic sucrose solution to eliminate the outside ions in order to better analyse their intracellular ionic composition; however, this approach was not feasible because of a substantial salt efflux from the cells. A prominent feature of the salt loss is the shrinking of the RBCs. A central role in the understanding of the ionic movements is thereby the new Donnan equilibrium of the anions. Experimental evidence has been given by Jacobs MH and Parpart AK in 1933. In the sucrose medium two phases could be predicted: 1) a very rapid anionic shift resulting in an unequal distribution of chloride and hydroxyl anions on both sides of the membrane and 2) a leakage of salts from the RBCs. In 1940 Wilbrandt W assumed that a positive membrane potential is in line with the salt loss at low ionic strength in RBCs. In 1977 Knauf PA, Fuhrmann GF, Rothstein S and Rothstein A observed in RBCs an inhibition of both, anion exchange and also of net anion efflux, by incubation with disulfonic stilbene derivates. At low ionic strength the Donnan equilibrium is immediately obtained by the Anion Exchanger Protein (AEP). The resulting positive membrane potential opens at least two new types of cation pores or channels. Thereby is the conductivity pathway for the anions, namely the AEP, in charge of the net anion loss at low ionic strength. The AEP pathway is extensively blocked by disulfonic stilbene compounds. The permeability ways for cations through these pores or channels are not yet explored.

Role of chloride in potassium transport through a K-Cl cotransport system in human red blood cells

1989 ◽  
Vol 256 (5) ◽  
pp. C994-C1003 ◽  
Author(s):  
C. Brugnara ◽  
T. Van Ha ◽  
D. C. Tosteson
Keyword(s):  
Membrane Potential ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Normal Subjects ◽  
Similar Data ◽  
Human Red Blood Cells ◽  
Dense Fraction ◽  
Cotransport System ◽  
Low K

In this paper, we report experiments demonstrating the coupling of Cl and K movements in a volume-dependent K-Cl cotransport system in human red blood cells. We show that an outwardly directed Cl gradient can promote net K efflux against an inwardly directed K gradient at constant membrane potential. Red blood cell membrane potential was kept constant by using anions that are not transported through the K-Cl cotransport system but that are more permeable than Cl (NO3 and SCN). Under these conditions, when the activities of band 3 (capnophorin)-mediated anion exchange and of the carbonic anhydrase have been inhibited, it is possible to maintain a Cl gradient at constant membrane potential. Similar data were obtained in human red blood cells (least dense fraction from normal subjects and whole blood from patients with homozygous hemoglobin S disease), in rabbit red blood cells, and in low-K sheep red blood cells. These data confirm that the volume-dependent Cl-dependent K movement in these cells operates through coupled K-Cl cotransport.

scholarly journals Transmembrane Potential of Red Blood Cells Under Low Ionic Strength Conditions

2013 ◽  
Vol 31 (6) ◽  
pp. 875-882 ◽  
Author(s):  
Daniel Moersdorf ◽  
Stephane Egee ◽  
Claudia Hahn ◽  
Benjamin Hanf ◽  
Clive Ellory ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Transmembrane Potential ◽  
Low Ionic Strength
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