scholarly journals Kinetics of bicarbonate and chloride transport in human red cell membranes.

1991 ◽  
Vol 97 (2) ◽  
pp. 321-349 ◽  
Author(s):  
P K Gasbjerg ◽  
J Brahm
Keyword(s):  
Chloride Transport ◽  
Anion Binding ◽  
Maximum Flux ◽  
Half Saturation Constant ◽  
Binding Inhibition ◽  
Filtering Technique ◽  
Red Cell Membranes ◽  
Kinetics Of ◽  
Bicarbonate And Chloride Transport ◽  
Human Red Cells

Unidirectional [14C]HCO3- and 36Cl- efflux from human red cells and ghosts was studied under self-exchange conditions at pH 7.8 and 0 degrees C by means of the Millipore-Swinnex filtering technique. Control bicarbonate experiments showed that 14CO2 loss from the cells to the efflux medium was insignificant. The anion flux was determined under (a) symmetric variations of the anion concentration (C(i) = C(o) = 5-700 mM), and (b) asymmetric conditions with CAn constant on one side and varied on the other side of the membrane. Simple Michaelis-Menten-like kinetics (MM fit: J(eff) = J(eff)max.C/(K1/2 + C)) was used to describe anion flux dependence on C for (a) C(i) = C(o) = 5-100 mM, (b) C(i) = 6-100 mM, C(o) = constant, and (c) C(i) = constant, C(o) = 1-25 mM. At higher cellular concentrations noncompetitive self-inhibition by anion binding (inhibition constant Ki mM) to an intracellular site was included in the model (MS fit): J(eff) = J(eff)max.C(i)/[(K1/2 + C(i)).(1 + C(i)/Ki)]. The MM fits show that the external half-saturation constant, Ko1/2 ( = C(o)An for J(eff,o) = 1/2.j(eff,o)max) at C(o) = 1-25 mM is 1.5-2.4 mM (HCO3-) and 1.8-2.6 mM (Cl-). At C(o) = 1-260 mM Ko1/2 is 1.2-1.5 mM (HCO3-) and 1.4-1.8 mM (Cl-). The respective maximum flux, J(eff,o)max (nmol/[cm2.s]), for C(o) = 1-25 mM is 0.41-0.51 (HCO3-) and 0.28-0.38 (Cl-), and for C(o) = 1-260 mM 0.39-0.44 (HCO3-) and 0.27-0.31 (Cl-). The internal half-saturation constant, Ki1/2 mM is: MM fit (C(i) = 6-100 mM, C(o) = 50 mM), 18.0 mM (HCO3-) and 23.8 mM (Cl-); MS fit (C(i) = 6-920 mM, C(o) = 50 mM), 32.0 mM (HCO3-) and 45.1 mM (Cl-). The maximum flux, J(eff,i)max (nmol/[cm2.s]) is: MM fit; 0.50 (HCO3-) and 0.34 (Cl-); MS fit, 0.70 (HCO-3) and 0.50 (Cl-). The half-inhibition constants of the MS fit, Ki, are 393 mM (HCO3-) and 544 mM (Cl-). The MM fit shows that the symmetric half-saturation constant, Ks1/2, is 20.2 (HCO-3) and 23.9 (Cl-) mM, and J(eff,s)max is 0.51 (HCO3-) and 0.32 (Cl-) nmol/(cm2.s). The MS fit shows that for C = 5-700 mM Ks1/2 is 30.4 nM (HCO3-) and 50.1 mM (Cl-), and Ki is 541 mM (HCO3-) and 392 mM (Cl-).(ABSTRACT TRUNCATED AT 400 WORDS)

The change from symmetry to asymmetry of a sodium transport system in red cell membranes

1985 ◽  
Vol 223 (1233) ◽  
pp. 449-457 ◽  
Keyword(s):  
Sodium Concentration ◽  
Tracer Studies ◽  
Chloride Medium ◽  
Sodium Influx ◽  
Nitrate Medium ◽  
Sodium Efflux ◽  
External Potassium ◽  
Red Cell Membranes ◽  
Stimulation Of ◽  
Human Red Cells

A study has been made with human red cells of sodium movements that are sensitive to the drug furosemide. The aim was to see if furosemide-sensitive movements that are symmetrical (exchange) became asymmetrical (net transport) on replacement of chloride with nitrate as the major external anion. Cells were incubated for 4 h at 37 °C with 140 mm sodium, and chloride or nitrate as the principal anion. Under a variety of conditions (presence and absence of ouabain or furosemide, or both) the cell sodium concentration was always higher when chloride was replaced with nitrate. The cells became leakier to sodium. Tracer studies indicated that, in contrast to the results in chloride medium, the decrease in sodium influx was greater than the fall in efflux when furosemide was added to cells in nitrate medium. The results confirm that the sensitivity of sodium efflux to furosemide depended on chloride. However, influx showed a different sensitivity in that furosemide still inhibited in cells incubated in nitrate medium. The stimulation of sodium influx with nitrate medium was independent of external potassium (10–50 mm) and the furosemide-sensitive influx was also constant. It is concluded that symmetrical transmembrane sodium movements with cells in chloride medium became downhill asymmetrical in nitrate medium, giving a net gain of cell sodium that was insensitive to ouabain and sensitive to furosemide. The drug thus partly retarded the gain of cell sodium that otherwise occurred in the somewhat leaky cells.

Specific Anion Binding to Sulfobetaine Micelles and Kinetics of Nucleophilic Reactions

2007 ◽  
Vol 111 (33) ◽  
pp. 9762-9769 ◽  
Author(s):  
Luisa Marte ◽  
Rosane C. Beber ◽  
M. Akhyar Farrukh ◽  
Gustavo A. Micke ◽  
Ana C. O. Costa ◽  
...  
Keyword(s):  
Anion Binding ◽  
Nucleophilic Reactions ◽  
Kinetics Of

Acetylcholinesterase in Human Erythroid Cells

1973 ◽  
Vol 12 (3) ◽  
pp. 911-923
Author(s):  
R. J. SKAER
Keyword(s):  
Endoplasmic Reticulum ◽  
Nervous System ◽  
Golgi Apparatus ◽  
Red Cells ◽  
The Other ◽  
Red Cell ◽  
Erythroid Cells ◽  
Cell Replacement ◽  
Kinetics Of ◽  
Human Red Cells

Acetylcholinesterase is present in human red cells but cannot be demonstrated by the copper thiocholine test. The enzyme is revealed, however, in the perinuclear cisterna, endoplasmic reticulum and Golgi apparatus of red cell precursors. It is suggested that 2 forms of the enzyme are present, one of which can be demonstrated by the copper thiocholine test, the other cannot; one form may be the precursor of the other. These observations may cast light on the kinetics of red cell replacement and on the interpretation of the results from the copper thiocholine test on other tissues such as the nervous system.

Active Chloride Transport by the Gills of Rainbow Trout (Salmo Gairdneri)

1972 ◽  
Vol 56 (1) ◽  
pp. 263-272
Author(s):  
THEODORE H. KERSTETTER ◽  
LEONARD B. KIRSCHNER
Keyword(s):  
Chloride Transport ◽  
Gill Filament ◽  
Salmo Gairdneri ◽  
Apparent Effect ◽  
Chloride Uptake ◽  
Potassium Influx ◽  
The Mean ◽  
Kinetics Of ◽  
Trout Gill ◽  
Penetrating Cations

1. The kinetics of chloride transport by the irrigated trout gill have been studied. The transport system is saturable, and the half-saturation value is about 0.25mM. 2. Chloride uptake occurs equally well from solutions of non-penetrating cations and from NaCl solutions. The presence of potassium in the irrigating solution, however, significantly inhibits chloride uptake. 3. The trout gill is permeable to potassium, and there appears to be an active component to potassium influx. 4. Chloride transport is stimulated by injections of NaHCO3 and (NH4)HCO3. The carbonic anhydrase inhibitor, acetazolamide, has no apparent effect on chloride influx, and it is suggested that if a Cl-/HCO3- exchange exists in the trout gill, sufficient HCO3- can be supplied by the blood. 5. The mean intracellular potential (relative to the irrigating solution) of five gill filament cells was -32 mV. This indicates the presence of an energy barrier to chloride uptake at the outer membrane of the epithelium, and therefore it is postulated that an active step for chloride transport is located on this membrane.

Anion binding inhibition of the formation of a helical organogel

2006 ◽  
pp. 3199 ◽  
Author(s):  
Claire E. Stanley ◽  
Nigel Clarke ◽  
Kirsty M. Anderson ◽  
Judith A. Elder ◽  
Joseph T. Lenthall ◽  
...  
Keyword(s):  
Anion Binding ◽  
Binding Inhibition

scholarly journals K-Na EXCHANGE ACCOMPANYING THE PROLYTIC LOSS OF K FROM HUMAN RED CELLS

1947 ◽  
Vol 30 (5) ◽  
pp. 379-387 ◽  
Author(s):  
Eric Ponder
Keyword(s):  
Steady State ◽  
Cell Metabolism ◽  
Ionic Composition ◽  
Surface Membrane ◽  
Sodium Taurocholate ◽  
Red Cells ◽  
Red Cell ◽  
Membrane Changes ◽  
Kinetics Of ◽  
Human Red Cells

In systems containing human red cells and sodium taurocholate as a lysin, or distearyl lecithin as a sphering agent, the prolytic loss of K at 25°C. is accompanied by a gain of Na by the cell, the gain being somewhat greater than the K loss. A small volume increase accompanies the exchange. The kinetics of the K loss and the Na gain are similar to those already described; i.e., the changes are rapid at first, and slow down so that after 12 to 20 hours it appears that a new steady state is being approached. Similar, but smaller, losses of K and gains of Na occur when the cells stand in isotonic NaCl at 25°C. without the addition of a lysin or sphering agent. On these and other experimental grounds, it is impossible to retain the idea that the mammalian red cell in general is impermeable to cations. The cells nevertheless seem to be in a steady state with respect to their environment, their ionic composition changing as the composition of the environment is changed. The possible processes by means of which one steady state can be exchanged for another—changes in the permeability of a surface membrane, changes in the velocity of an active ion transfer process dependent on red cell metabolism, and changes in the activity of the ions in the red cell interior as a result of changes in an orderly internal structure—are discussed.

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