Chloride transport in red blood cells of lamprey lampetra fluviatilis: evidence for a novel anion-exchange system

1998 ◽  
Vol 201 (5) ◽  
pp. 693-700 ◽  
Author(s):  
A Bogdanova ◽  
A Sherstobitov ◽  
G P Gusev
Keyword(s):  
Anion Exchange ◽  
Erythrocyte Membrane ◽  
Chloride Transport ◽  
Exchange System ◽  
Transport Pathway ◽  
Lampetra Fluviatilis ◽  
Transport Pathways ◽  
Cl Transport ◽  
K Concentration ◽  
External K

The existence of a furosemide-sensitive Cl- transport pathway activated by external Ca2+ and Mg2+ has been demonstrated previously in studies of Cl- influx across the lamprey erythrocyte membrane. The aim of the present study was to characterize further specific Cl- transport pathways, especially those involved in Cl- efflux, in the red blood cell membrane of Lampetra fluviatilis. Cl- efflux was inhibited by 0.05 mmol l-1 dihydroindenyloxyalkanoic acid (DIOA) (81 %), 1 mmol l-1 furosemide (76 %) and 0.1 mmol l-1 niflumic acid (54 %). Bumetanide (100 micromol l-1) and DIDS (100 micromol l-1) had no effect effect on Cl- efflux. Substitution of external Cl- by gluconate, but not by NO3-, led to a gradual decline of Cl- efflux. In addition, the removal of external Ca2+ resulted in a significant reduction in the rate of Cl- efflux. Membrane depolarization caused by increasing external K+ concentration or by inhibiting K+ channels with 1 mmol l-1 Ba2+ did not affect Cl- efflux. The furosemide-sensitive component of Cl- influx was a saturable function of external [Cl-] with an apparent Km of approximately 92 mmol l-1 and Vmax of approximately 17.8 mmol l-1 cells-1 h-1. Furosemide did not affect intracellular Cl- concentration (57.6+/-5. 2 mmol l-1 cell water), measured using an ion-selective Cl- electrode, showing that a furosemide-sensitive pathway is not involved in net Cl- movement. A gradual fall (from 28.1+/-1.4 to 15. 0+/-1.3 mmol l-1 cells-1 h-1) in unidirectional Cl- influx with time was observed within 3 h of cell preincubation in the standard physiological medium. These data provide evidence for the existence for an electroneutral furosemide-sensitive anion-exchange pathway in the lamprey erythrocyte membrane that accepts chloride and nitrate, but not bicarbonate or bromide.

scholarly journals The effect of N-ethylmaleimide on K+ and Cl- transport pathways in the lamprey erythrocyte membrane: activation of K+/Cl- cotransport

1991 ◽  
Vol 159 (1) ◽  
pp. 325-334 ◽  
Author(s):  
K. Kirk
Keyword(s):  
Erythrocyte Membrane ◽  
Mammalian Species ◽  
Individual Case ◽  
Mean Value ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Physiological Conditions ◽  
Cl Transport ◽  
Dependent Component ◽  
K Transport

The effect of the sulphydryl reagent N-ethylmaleimide on the K+ and Cl- transport pathways of the lamprey erythrocyte membrane was found to be quite complex. N-Ethylmaleimide inhibited the Ba(2+)-sensitive pathway that mediates most of the ouabain-resistant influx of K+ into the cell under physiological conditions but stimulated a Cl(−)-dependent, B(2+)-resistant K+ transport pathway that was inhibited by compounds that inhibit Cl(−)-dependent K+ transport in the human erythrocyte. N-Ethylmaleimide (in most cases) reduced the total influx of Cl- into the lamprey erythrocyte but (in all cases) introduced a K(+)-dependent component into the measured Cl- uptake; this was explained in terms of N-ethylmaleimide having inhibited the pathway primarily responsible for Cl- influx under physiological conditions but having stimulated a second, K(+)-dependent Cl- transport pathway. Although the magnitude of the K+ and Cl- fluxes stimulated by N-ethylmaleimide varied widely between cells from different lampreys, there was, in each individual case, a close similarity between the magnitude of the Cl(−)-dependent K+ influx (calculated from the 86Rb+ uptake) and the K(+)-dependent Cl- influx; the mean value for the ratio of the former to the latter was 1.01 +/− 0.03 (N = 5). The results are therefore consistent with the sulphydryl reagent having activated a K+/Cl- cotransport system similar to that present in erythrocytes from many mammalian species. This raises the possibility that the lamprey red cell may be a uniquely suitable system in which to study the characteristics of Cl- transport by this pathway.

K+ transport across the lamprey erythrocyte membrane: characteristics of a Ba(2+)- and amiloride-sensitive pathway

1991 ◽  
Vol 159 (1) ◽  
pp. 303-324 ◽  
Author(s):  
K. Kirk
Keyword(s):  
Membrane Potential ◽  
Erythrocyte Membrane ◽  
Inhibitory Effect ◽  
Extracellular Ph ◽  
Transport Pathway ◽  
Full Effect ◽  
River Lamprey ◽  
K Concentration ◽  
86Rb Influx ◽  
K Transport

The characteristics of K+ transport in erythrocytes from the river lamprey (Lampetra fluviatilis) were investigated using standard radioisotope flux techniques. The cells were shown to have a ouabain-sensitive transport pathway that carried 43K+ and 86Rb+ into the cell at similar rates. Most of the ouabain-resistant 43K+ and 86Rb+ influx was via a pathway that was insensitive to cotransport inhibitors and to the replacement of extracellular Cl- or Na+. This pathway showed a strong selectivity for 43K+ over 86Rb+. It was inhibited fully by Ba2+ (I50 approximately 2.8 mumol l-1), amiloride (I50 approximately 150 mumol l-1) and ethylisopropylamiloride (I50 approximately 3.3 mumol l-1) and less effectively by quinine and by the tetraethylammonium ion. Inhibition by Ba2+ took full effect within a few minutes whereas the full inhibitory effect of amiloride took more than 1 h to develop. Experiments with the membrane potential probe [14C]tetraphenylphosphonium ion gave results consistent with the lamprey erythrocyte membrane having a Ba(2+)-sensitive K+ conductance that was significantly greater than the membrane Na+ conductance and which gave rise to a marked dependence of the membrane potential on the extracellular K+ concentration. The rate constants for Ba(2+)-sensitive 43K+ and 86Rb+ influx decreased (proportionally) with increasing extracellular K+ concentration in a manner that was consistent with the transport being via a conductive pathway. The decrease was attributed to a depolarisation of the membrane (in response to the increasing extracellular K+ concentration) and a consequent decrease in the driving force for the conductive movement of 43K+ and 86Rb+ into the cells. Ba(2+)-sensitive 86Rb+ influx increased significantly with decreasing cell volume and with increasing intracellular pH (at a constant extracellular pH) but increased only slightly with increasing extracellular pH. The pathway operated normally in the complete absence of extracellular Ca2+ but its activity decreased in cells pretreated with ionomycin and EGTA; this suggests a role for intracellular Ca2+ in the operation of the pathway.

Regulation of ion transport across lamprey (Lampetra fluviatilis) erythrocyte membrane by oxygen tension

1998 ◽  
Vol 201 (12) ◽  
pp. 1927-1937 ◽  
Author(s):  
LV Virkki ◽  
A Salama ◽  
M Nikinmaa
Keyword(s):  
Ion Transport ◽  
Erythrocyte Membrane ◽  
Oxygen Tension ◽  
Radioactive Isotope ◽  
Marked Reduction ◽  
Marked Effect ◽  
Hypotonic Medium ◽  
Lampetra Fluviatilis ◽  
Transport Pathways ◽  
Hypoxic Conditions

We have measured the effects of oxygen tension on the transport of Na+, K+ and Cl- across the erythrocyte membrane of the lamprey Lampetra fluviatilis. The transport of each ion was affected by the oxygen tension of the medium. Hypoxic conditions (PO2 2 kPa) caused an increase in the acidification-induced influx of Na+ via Na+/H+ exchange. The influx of K+ was only slightly affected by the oxygenation of the medium. In contrast, the basal K+ efflux, measured using the radioactive isotope 43K, was markedly reduced by decreasing the oxygen tension of the medium, whereas the K+ flux in hypotonic medium was not affected. Only minor effects of hypoxic conditions on the influx of Cl- were observed in either isotonic or hypotonic conditions (there was a tendency for the isotonic influx to increase) or on the efflux in isotonic conditions. However, deoxygenation caused a marked reduction in the Cl- efflux in hypotonic conditions. The results show that oxygen tension has a marked effect on the pH and volume regulatory transport pathways of lamprey erythrocytes. For K+ and Cl-, the regulation appears to be asymmetric, i.e. influx and efflux are affected differently.

Altered Erythrocyte Cation Permeability in Familial Pseudohyperkalaemia

1989 ◽  
Vol 77 (2) ◽  
pp. 213-216 ◽  
Author(s):  
G. Dagher ◽  
M. C. Vantyghem ◽  
B. Doise ◽  
G. Lallau ◽  
A. Racadot ◽  
...  
Keyword(s):  
Marked Reduction ◽  
Cation Transport ◽  
Transport Pathway ◽  
Passive Permeability ◽  
Transport Pathways ◽  
Control Subjects ◽  
Na Permeability ◽  
Cation Permeability ◽  
The Family ◽  
K Concentration

1. Erythrocyte cation transport pathways have been investigated in a family with pseudohyperkalaemia. 2. Ouabain- and bumetanide-resistant Na+ and K+ effluxes in three pseudohyperkalaemic patients were not different from those of control subjects when assessed at 37°C. 3. When the temperature was decreased to 20°C and 9°C, K+ passive permeability markedly increased and Na+ permeability remained unchanged in these patients. In contrast, in control subjects a reduction in temperature caused a marked reduction in Na+ and K+ passive permeability. 4. These findings could account for the marked increase in plasma K+ concentration observed at sub-physiological temperatures. 5. The Na+−K+ co-transport pathway was reduced in all members of the family, but the Na+−K+ pump was reduced in only two of them. These alterations were independent from the pseudohyperkalaemic state.

Cation and anion transport pathways in volume regulatory response of human lymphocytes to hyposmotic media

1985 ◽  
Vol 248 (5) ◽  
pp. C480-C487 ◽  
Author(s):  
B. Sarkadi ◽  
R. Cheung ◽  
E. Mack ◽  
S. Grinstein ◽  
E. W. Gelfand ◽  
...  
Keyword(s):  
Human Lymphocytes ◽  
Regulatory Volume Decrease ◽  
Anion Transport ◽  
Red Cells ◽  
K Channel ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Calmodulin Antagonist ◽  
Cl Transport ◽  
K Transport

The regulatory volume decrease of osmotically swollen human peripheral blood lymphocytes can be inhibited by agents acting on volume-activated K+- or Cl--transport pathways. Quinine, cetiedil, and 3,3'-dipropylthiadicarbocyanine were found to block the volume-induced K+ transport by interaction with sites on the outside face of the membrane, perhaps by competition with external K+. Drugs known to influence calmodulin action inhibit both volume-induced K+ and Cl- transport to varying degrees. Those inhibitors, particularly of K+ transport, are correlated with their calmodulin-antagonist activity. Penetrating sulfhydryl (SH) reagents (in contrast to nonpenetrating ones) are potent inhibitors of both volume-induced K+ and Cl- movements, indicating the presence of functionally important SH groups located within the membrane or at the cytoplasmic face. A number of agents, such as dipyridamole and oligomycin C, are specific inhibitors of the volume-activated anion pathway. In all respects studied, the inhibition characteristics of the volume-activated K+ pathway of lymphocytes resemble those of the Ca2+-activated K+ channel of red cells. In contrast, the volume-induced anion permeability differs from the primary anion-transport pathway of red cells.

scholarly journals Asymmetry of the red cell anion exchange system. Different mechanisms of reversible inhibition by N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate (NAP-taurine) at the inside and outside of the membrane.

1978 ◽  
Vol 72 (5) ◽  
pp. 607-630 ◽  
Author(s):  
P A Knauf ◽  
S Ship ◽  
W Breuer ◽  
L McCulloch ◽  
A Rothstein
Keyword(s):  
Anion Exchange ◽  
Chloride Transport ◽  
External Solution ◽  
Reversible Inhibitor ◽  
Red Cell ◽  
Exchange System ◽  
Chloride Exchange ◽  
A Site ◽  
Two Sides ◽  
Transport Site

In the dark, the photoaffinity reagent, N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate (NAP-taurine), acts as a reversible inhibitor of red cell anion exchange when it is present either within the cell or in the external solution. A detailed analysis of the inhibition kinetics, however, reveals substantial differences in the responses to the probe at the two sides of the membrane. On the inside of the cell, NAP-taurine is a relatively low affinity inhibitor of chloride exchange (Ki = 370 microM). Both the effects of chloride on NAP-taurine inhibition and the affinity of NAP-taurine for the system as a substrate are consistent with the concept that internal NAP-taurine competes with chloride for the substrate site of the anion exchange system. External NAP-taurine, on the other hand, is a far more potent inhibitor of chloride exchange (Ki = 20 microM). It acts at a site of considerably lower affinity for chloride than the substrate site, probably the modifier site, at which halide anions are reported to cause a noncompetitive inhibition of chloride transport. NAP-taurine therefore seems to interact preferentially with either the substrate or modifier site of the transport system, depending on the side of the membrane at which it is present. It is suggested that the modifier site is accessible to NAP-taurine only from the outside whereas the transport site may be accessible from either side.

Electrogenic, K + -dependent chloride transport in locust hindgut

1982 ◽  
Vol 299 (1097) ◽  
pp. 585-595 ◽  
Keyword(s):  
Chloride Transport ◽  
Passive Movement ◽  
Water Reabsorption ◽  
Experimental Conditions ◽  
Cl Transport ◽  
Neuropeptide Hormone ◽  
Flux Measurements ◽  
Ion Sensitive Microelectrodes ◽  
Voltage Clamping ◽  
Electrochemical Potentials

Potassium chloride is the major salt recycled in most insect excretory systems. Ion and water reabsorption occur in the rectum by active transport of Cl- and largely passive movement of K+. Both these processes are stimulated several fold by a neuropeptide hormone acting via cyclic AMP (cAMP). This Cl- transport process was investigated by using intracellular ion-sensitive microelectrodes, radiotracer flux measurements, voltage clamping, ion substitutions and inhibitors. The mucosal entry step for Cl- is energy-requiring and highly selective, and is stimulated directly by cAMP and luminal K +. Under some experimental conditions, measured electrochemical potentials for cations across the mucosal membrane are too small to drive Cl- entry by NaCl or KC1 cotransport mechanisms; moreover, net 36C1- flux is independent of the apical Na+ potential. Similarly no evidence for a HCO 3 -Cl- exchange was obtained. We conclude that Cl- transport in locust gut is different from mechanisms currently proposed for vertebrate tissues.

Na and Cl Transport across the Isolated Anterior Intestine of the Plaice Pleuronectes Platessa

1981 ◽  
Vol 90 (1) ◽  
pp. 123-142
Author(s):  
M. M. P. RAMOS ◽  
J. C. ELLORY
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Negative Potential ◽  
Loop Diuretics ◽  
Significant Part ◽  
Cl Transport ◽  
Anterior Intestine ◽  
Short Circuit Currents ◽  
Na Uptake

1. The tissue was found to have a serosa negative potential, and short-circuit currents equivalent to the net Cl transport. 2. A significant part of the Cl uptake was Na dependent and a similar fraction of the Na uptake was Cl dependent. 3. Short-circuit current and uptake of both ions were inhibited by loop diuretics and analogues. 4. I80 and P.D. were abolished by ouabain. 5. The observations are consistent with the idea of a coupled NaCl entry into the cell, using the energy inherent in the Na gradient; Na being pumped out of the cells by the Na pump and followed electrically by Cl−. Net chloride transport and the serosa negative potential would be a consequence of the permselective properties of the junctions allowing Na but not Cl to recycle back to the mucosal solution.

scholarly journals Further Observations on the Regulation of KCl ABSORPTION ACROSS LOCUST RECTUM

1985 ◽  
Vol 116 (1) ◽  
pp. 153-167
Author(s):  
J. W. HANRAHAN ◽  
J. E. PHILLIPS
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Membrane Conductance ◽  
Short Circuit Current ◽  
Membrane Resistance ◽  
Open Circuit ◽  
High K ◽  
K Concentration ◽  
K Permeability

1. Electrophysiological and tracer flux techniques were used to studyregulation of KC1 reabsorption across locust recta. Physiologically high K+levels (100 mmolI−1) on the lumen side stimulated net 36Cl flux and reduced the theoretical energy cost of anion transport under open-circuit conductions. 2. The stimulation of short-circuit current (Ibc i.e. active C− absorption) by crude corpora cardiaca extracts (CC) was not dependent on exogenous Ca2+. Stimulations of Ibc were greatly enhanced in the presence of theophylline, indicating that the rate of synthesis of cAMP is increased by CC extracts. High CC levels lowered transepithelial resistance (Rt), suggesting that chloride transport stimulating hormone (CTSH) regulates both active Cl− absorption and counter-ion (K+) permeability. 3. High mucosal osmolarity or K+ concentration decreased Ibc and caused a disproportionately large increase in Rt, consistent with a decrease in theshunt (K+) conductance. Measurements of relative mucosal-to-serosal membrane resistance confirmed that high mucosal K+ levels reduced apical membrane conductance. Lowering mucosal pH to values observed in vivo atthe end of resorptive cycles also inhibited Ibc, apparently without affecting K+ permeability.

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