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  • 1
    Electronic Resource
    Electronic Resource
    Increased human red cell cation passive permeability below 12 °C (1980)
    [s.l.] : Nature Publishing Group
    Nature 286 (1980), S. 403-404 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Surprisingly few data are available on the effects of temperature on Na and K transport in human erythrocytes. This may be due in part to the presence of at least three components of Na and K movement in human red cells. These can be resolved as the ouabain-sensitive Na-K pump1'2, the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/286403a0
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of the substituted benzaldehyde 12C79 on Cl–-dependent K+ influx in human red blood cells (1999)
    Springer
    Pflügers Archiv 437 (1999), S. 498-500 
    Details
    ISSN: 1432-2013
    Keywords: Key words 12C79 ; HbA ; KCC1 ; KCl cotransport ; Oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Ouabain- and bumetanide-resistant K+ influx, and haemoglobin (Hb) O2 saturation, were measured in HbA red cells over a range of oxygen tensions (PO2 values) in the presence and absence of 12C79 (5 mM), a substituted benzaldehyde which increases the O2 affinity of Hb. PO2 values for half-maximal O2 saturation declined from 29±2 mmHg (mean ±SEM, n=3) in control cells to 7±1 mmHg with 12C79. In control cells, Cl–-dependent K+ influx (indicative of KCl cotransport activity) was fully O2 dependent, i.e. inactive at low PO2 values. By contrast, in the presence of 12C79, KCl cotransport was largely resistant to inactivation at low PO2 values. Substantial cotransport activity was still present (〉60% of that at high PO2 values) in N2, although O2 saturation was low (about 10%). In all cases, Cl–-independent K+ influxes were low [〈0.25 mmol (l cells h)–1] and unaffected by PO2 or 12C79. The significance of these results is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050807
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  • 3
    Electronic Resource
    Electronic Resource
    Regulatory volume response of erythrocytes exposed to a gradual and slow decrease in medium osmolality (1999)
    Springer
    Pflügers Archiv 437 (1999), S. 776-779 
    Details
    ISSN: 1432-2013
    Keywords: Key words Cell volume regulation ; Hypotonic swelling ; KCl cotransport ; Red blood cells ; RVD ; Taurine transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A sudden decrease in external medium osmolality (90 mosmol/kg) causes an immediate swelling of trout erythrocytes, followed by a regulatory volume decrease (RVD) due to activation of both a KCl cotransporter and a taurine transport pathway. Here, we determined how trout red cells respond when they are exposed to a gradual and slow decrease in medium osmolality (80 mosmol/kg at a rate of 0.7 mosmol/kg per min). Erythrocytes were unable to regulate their volume efficiently when swollen gradually and it increased continuously throughout the experimental period (120 min). As long as volume was increased slowly by 15–25%, regulatory pathways remained essentially inactivated, erythrocytes losing no significant amount of intracellular osmotically active solutes. Above this swelling threshold, a response was triggered but the quantity of solutes lost via the regulatory pathways was still not sufficient to counterbalance the continuous entry of water due to the slow and gradual decrease in medium tonicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050845
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of urea and oxygen tension on K flux in sickle cells (1998)
    Springer
    Pflügers Archiv 435 (1998), S. 740-742 
    Details
    ISSN: 1432-2013
    Keywords: Key words Sickle cell ; HbS ; KCl cotransport ; Urea ; Oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  K influx and efflux (both ouabain- and bumetanide-resistant) in haemoglobin S-containing red cells (sickle cells) were markedly stimulated by urea (〉 0.25 M). Stimulation was rapid and reversible. Volume-sensitive KCl cotransport in both HbA or HbS red cells is thought to be O2-dependent but we show here that urea-stimulated K fluxes in sickle cells were largely insensitive to O2 tension. Urea-stimulated K fluxes were not inhibited by lowering the external Ca concentration (with EGTA) but were abolished by Cl-substitution (with MeSO4 or NO3) or pretreatment of cells with the protein phosphatase inhibitor, calyculin A (0.1 μM). Results are consistent with a stimulatory action of urea on the KCl cotransporter, independent of oxygen tension, mediated via the phosphorylation cascade which regulates the transporter. The importance of this effect to the physiology and pathology of sickle cells is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050576
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  • 5
    Electronic Resource
    Electronic Resource
    Interaction of L antibody with low potassium-type sheep red cells: Resolution of two separate functional antibodies (1982)
    Springer
    The journal of membrane biology 64 (1982), S. 167-174 
    Details
    ISSN: 1432-1424
    Keywords: red cell membranes ; potassium transport ; alloimmune antiserum ; high K-low K polymorphism ; sheep red cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Antibodies of two specificities in alloimmune sheep anti-L sera, anti-L P and anti-L l , were separated by a new technique and characterized. Absorption of anti-L serum with trypsinized LK (LL) sheep red cells left anti-L P antibodies; the absorbed anti-L l antibodies were then eluted. Anti-L P was only weakly lytic in the presence of complement; it had no effect on passive K influx, but stimulated active K influx. The stimulation could be reversed by eluting the antibody in glycine buffer at low pH. Stimulatory activity in the eluted cells could be restored by resensitization with anti-L P . Anti-L l was more strongly lytic than anti-L P in the presence of complement; it had no effect on active K influx, but inhibited passive K influx. Pig anti-ruminant IgG conjugated to hemocyanin was used to visualize by electron microscopy the number of L P and L l antigen sites onLL sheep red cells sensitized with anti-L P and anti-L l . The values obtained were 590 L P sites/cell and 847 L l sites/cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870882
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  • 6
    Electronic Resource
    Electronic Resource
    Interaction of alkyl ammonium derivatives with red cells: Hemolysis and sodium pump inhibition studies (1980)
    Springer
    The journal of membrane biology 55 (1980), S. 123-131 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Members of four homologous series of tetra-alkyl ammonium bromides (R 3N+(CH2) n−1·CH3Br− whereR=H, CH3 or C2H5 andR′N+H3Br− whereR′ represents the isomeric butyl series) have been synthesized and tested as sodium pump inhibitors, measured as ouabain-sensitive K+ influx, and as hemolytic agents on human red cells. Potency for both effects is presented graphically, plotting the logarithm of the concentration for half maximal effect against alkyl chain length. Both hemolysis and pump inhibition studies yielded a biphasic response consisting of two good straight lines, with effectiveness increasing up to C10–12 and then remaining constant up to C20. For hemolysis the alkyl ammonium series was most effective. The calculated free-energy change per methylene group was the same for three series of compounds, but the free-energy contribution from the headgroup was lower for the ammonium series. In contrast, although pump inhibition studies also yielded simple biphasic plots, inhibition occurred at 3- to 50-fold lower concentrations and there were significant differences between the three series, both in the free-energy changes per methylene group and in the headgroup contributions. We have analyzed these results thermodynamically to take account of hydrophobic interactions and the conformation of the alkyl chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871154
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  • 7
    Electronic Resource
    Electronic Resource
    Pressure and temperature effects on human red cell cation transport (1982)
    Springer
    The journal of membrane biology 68 (1982), S. 47-56 
    Details
    ISSN: 1432-1424
    Keywords: hydrostatic pressure ; potassium flux ; erythrocyte membrane ; water of hydration ; anion effect ; thermodynamic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of hydrostatic pressure and temperature on the three components of K+ uptake in human red cells have been investigated, using ouabain and bumetanide to distinguish between the pump, passive diffusion and cotransport. The pressure sensitivity for passive diffusion has been shown to depend on the counter-ion present. The order of this effect, Cl−〉Br−〉NO 3 − 〉I−, is the same as for the ionic partial modal volumes and the Hofmeister series. We have analyzed our experimental results thermodynamically, and propose a model for the activated transition-state complex of the potassium ion which involves the loss of water molecules from the secondary hydration shell, cosphere II.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01872253
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  • 8
    Electronic Resource
    Electronic Resource
    Thiocyanate transport across fish intestine (Pleuronectes platessa) (1982)
    Springer
    The journal of membrane biology 66 (1982), S. 9-14 
    Details
    ISSN: 1432-1424
    Keywords: thiocyanate ; chloride ; transport ; intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary When bathed on both sides with identical chloride-containing salines thein vitro preparation of the plaice intestine maintains a negative (serosa to mucosa) short-circuit current of 107±11 μA/cm2, a transepithelial potential difference of 5.5±0.6 mV (serosa negative), and a mean mucosal membrane potential of −45.4±0.6 mV. Under these conditions the intracellular chloride activity is 32mm. If chloride in the bathing media is partially, or completely substituted by thiocyanate the measured electrical parameters do not change but transepithelial flux determinations show a reduction in chloride fluxes and the presence of a significant thiocyanate flux. The addition of piretanide (10−4 m) reduced the short-circuit current and the mucosa-to-serosa fluxes of chloride and thiocyanate; this inhibition is similar to the effect of piretanide on chloride transport in this tissue. The results indicate that thiocyanate is transported in this tissue via the piretanide-sensitive “chloride” pathway and are compared with the effects of thiocyanate on other tissues reported in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868477
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  • 9
    Electronic Resource
    Electronic Resource
    Temperature sensitivity of the sodium pump in red cells from various hibernator and non-hibernator species (1980)
    Springer
    Journal of comparative physiology 138 (1980), S. 43-47 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ouabain-sensitive K influx was measured at 5°C and 37°C in red cells from seven species of mammals known to hibernate, and nine species of non-hibernators. Care was taken to saturate the internal and external cation sites of the sodium pump, and maintain the cell metabolism. Species variation in ouabain-resistance among rodents was also taken into account. In six out of seven species of hibernators the pump was relatively insensitive to lowering the temperature, the ratio of activity at 5°C/37°C being 〉1.8%. By contrast eight of the nine non-hibernator species gave a ratio 〈1.8%. The two exceptions were the hamster, which gave a ratio of 0.8% as a hibernator, and the mole which gave a ratio of 3% as a non-hibernator. No similar correlation was observed for the ouabain-insensitive K influx, in either groups of animals. It is concluded that cold tolerance of the sodium pump is a general but not essential property of hibernator red cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688734
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