Effects of protein kinase and phosphatase inhibitors and anti-L antisera on K+ transport in LK sheep red cells

2000 ◽  
Vol 52 (2) ◽  
pp. 151-159 ◽  
Author(s):  
E.H. Campbell ◽  
J.C. Ellory ◽  
J.S. Gibson
Keyword(s):  
Protein Kinase ◽  
Red Cells ◽  
Phosphatase Inhibitors ◽  
Sheep Red Cells ◽  
K Transport

Swelling, NEM, and A23187 activate Cl(-)-dependent K+ transport in high-K+ sheep red cells

1987 ◽  
Vol 252 (2) ◽  
pp. C197-C204 ◽  
Author(s):  
H. Fujise ◽  
P. K. Lauf
Keyword(s):  
Metal Ion ◽  
Red Cells ◽  
Common Mechanism ◽  
Ionophore A23187 ◽  
Sheep Red Cells ◽  
High K ◽  
Sh Group ◽  
Low K ◽  
K Transport ◽  
Significant Activation

In low K+ (LK) sheep red cells a significant fraction of the total ouabain-resistant (OR) K+ flux is inhibited when Cl- is replaced by other anions of the Hofmeister series except Br- (Cl(-)-dependent K+ flux). In contrast, high K+ (HK) sheep red cells in isosmotic media did not possess any significant OR Cl(-)-dependent K+ flux when Cl- was replaced by NO3- or I-. However, exposure to hyposmotic solutions, treatment with the sulfhydryl (SH) group reagent N-ethylmaleimide (NEM) or with the bivalent metal ion (Me2+) ionophore A23187 in absence of external Me2+ caused a significant activation of Cl(-)-dependent K+ transport as measured with Rb+ as K+ congener. There was no Cl(-)-dependent Rb+ flux in A23187-treated cells when Mn2+, Mg2+, and Ca2+ were present at 1 mM concentrations, suggesting that cellular accumulation of these Me2+ is inhibitory. Similar to LK red cells, HK red cells failed to respond to A23187 when pretreated with NEM supporting the hypothesis proposed recently (Lauf, P. K. J. Membr. Biol. 88: 1-13, 1985) of a common mechanism of Cl(-)-dependent K+ transport activation. The magnitudes of the Cl(-)-dependent Rb+ fluxes in HK cells were much smaller than those elicited by identical treatments in LK red cells, and the effect of all interventions was not due to the presence of reticulocytes known to possess Cl(-)-dependent K+ transport.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Passive potassium transport in LK sheep red cells. Effects of anti-L antibody and intracellular potassium.

1976 ◽  
Vol 68 (6) ◽  
pp. 567-581 ◽  
Author(s):  
P B Dunham
Keyword(s):  
Maximum Velocity ◽  
Red Cells ◽  
Na Transport ◽  
Sheep Red Cells ◽  
The Common ◽  
K Concentration ◽  
Mode Of Transport ◽  
Low K ◽  
K Transport ◽  
External K

The passive K influx in low K(LK) red blood cells of sheep saturates with increasing external K concentration, indicating that this mode of transport is mediated by membrane-associated sites. The passive K influx, iMLK, is inhibited by external Na. Isoimmune anti-L serum, known to stimulate active K transport in LK sheep red cells, inhibits iMLK about twofold. iMLK is affected by changes in intracellular K concentration, [K]i, in a complex fashion: increasing [K]i from near zero stimulates iMLK, while further increases in [K]i, above 3 mmol/liter cells, inhibit iMLK. The passive K influx is not mediated by K-K exchange diffusion. The effects of anti-L antibody and [K]i on passive cation transport are specific for K: neither factor affects passive Na transport. The common characteristics of passive and active K influx suggest that iMLK is mediated by inactive Na-K pump sites, and that the inability to translocate Na characterizes the inactive pumps. Anti-L antibody stimulates the K pump in reticulocytes of LK sheep. However, anti-L has no effect on iMLK in these cells, apparently because reticulocytes do not have the inactive pump sites which, in mature LK cells, are a consequence of the process of maturation of circulating LK cells. The results also indicate that anti-L alters the maximum velocity of both active and passive K fluxes by converting pumps sites from a form mediating passive K influx to an actively transporting form.

scholarly journals Active Sodium and Potassium Transport in High Potassium and Low Potassium Sheep Red Cells

1971 ◽  
Vol 58 (4) ◽  
pp. 438-466 ◽  
Author(s):  
P. G. Hoffman ◽  
D. C. Tosteson
Keyword(s):  
Cell Types ◽  
Red Cells ◽  
Kinetic Characteristics ◽  
High Potassium ◽  
Cation Composition ◽  
Sheep Red Cells ◽  
Pump Rate ◽  
Low Potassium ◽  
K Transport ◽  
External K

The kinetic characteristics of the ouabain-sensitive (Na + K) transport system (pump) of high potassium (HK) and low potassium (LK) sheep red cells have been investigated. In sodium medium, the curve relating pump rate to external K is sigmoid with half maximal stimulation (K1/2) occurring at 3 mM for both cell types, the maximum pump rate in HK cells being about four times that in LK cells. In sodium-free media, both HK and LK pumps are adequately described by the Michaelis-Menten equation, but the K1/2 for HK cells is 0.6 ± 0.1 mM K, while that for LK is 0.2 ± 0.05 mM K. When the internal Na and K content of the cells was varied by the PCMBS method, it was found that the pump rate of HK cells showed a gradual increase from zero at very low internal Na to a maximum when internal K was reduced to nearly zero (100% Na). In LK cells, on the other hand, no pump activity was detected if Na constituted less than 70% of the total (Na + K) in the cell. Increasing Na from 70 to nearly 100% of the internal cation composition, however, resulted in an exponential increase in pump rate in these cells to about ⅙ the maximum rate observed in HK cells. While changes in internal composition altered the pump rate at saturating concentrations of external K, it had no effect on the apparent affinity of the pumps for external K. These results lead us to conclude that the individual pump sites in the HK and LK sheep red cell membranes must be different. Moreover, we believe that these data contribute significantly to defining the types of mechanism which can account for the kinetic characteristics of (Na + K) transport in sheep red cells and perhaps in other systems.

Effect of N-ethylmaleimide on K transport in density-separated human red blood cells

1987 ◽  
Vol 253 (1) ◽  
pp. C7-C12 ◽  
Author(s):  
L. R. Berkowitz ◽  
D. Walstad ◽  
E. P. Orringer
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Red Cells ◽  
Sheep Red Cells ◽  
Human Red Blood Cells ◽  
High K ◽  
K Transport ◽  
Human Red Cells

N-ethylmaleimide (NEM) is a sulfhydryl-reacting agent known to stimulate chloride-dependent K transport in a variety of red cells. In high K sheep red cells, NEM-induced K movements are greater in magnitude in young cells compared with old cells. We hypothesized that human red cells might respond to NEM like high K sheep red cells. To test this idea, cells of various age were exposed to 0.5 mM NEM. We found that, after a 4-h incubation, young cells lost 50% of cell K, compared with 10% K loss in older cells. K loss in all fractions was inhibited by chloride replacement or furosemide.

Receptors for IgG molecules on human lymphocytes forming spontaneous rosettes with sheep red cells

1975 ◽  
Vol 5 (1) ◽  
pp. 70-72 ◽  
Author(s):  
M. Ferrarini ◽  
L. Moretta ◽  
Roberte Abrile ◽  
Maria Laura Durnte
Keyword(s):  
Human Lymphocytes ◽  
Red Cells ◽  
Sheep Red Cells

scholarly journals CELLS INVOLVED IN THE IMMUNE RESPONSE

1969 ◽  
Vol 129 (4) ◽  
pp. 757-774 ◽  
Author(s):  
Nabih I. Abdou ◽  
Maxwell Richter
Keyword(s):  
Bone Marrow ◽  
Immune Response ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Bone Marrow Cells ◽  
Allogeneic Bone Marrow ◽  
Red Cells ◽  
Allogeneic Bone ◽  
Sheep Red Blood Cells ◽  
Sheep Red Cells

Irradiated rabbits given allogeneic bone marrow cells from normal adult donors responded to an injection of sheep red blood cells by forming circulating antibodies. Their spleen cells were also capable of forming many plaques using the hemolysis in gel technique, and were also capable of undergoing blastogenesis and mitosis and of incorporating tritiated thymidine upon exposure to the specific antigen in vitro. However, irradiated rabbits injected with allogeneic bone marrow obtained from rabbits injected with sheep red blood cells 24 hr prior to sacrifice (primed donors) were incapable of mounting an immune response after stimulation with sheep red cells. This loss of reactivity by the bone marrow from primed donors is specific for the antigen injected, since the immune response of the irradiated recipients to a non-cross-reacting antigen, the horse red blood cell, is unimpaired. Treatment of the bone marrow donors with high-titered specific antiserum to sheep red cells for 24 hr prior to sacrifice did not result in any diminished ability of their bone marrow cells to transfer antibody-forming capacity to sheep red blood cells. The significance of these results, with respect to the origin of the antigen-reactive and antibody-forming cells in the rabbit, is discussed.

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