Thiol-dependent passive K/Cl transport in sheep red cells: II. Loss of Cl− and N-ethylmaleimide sensitivity in maturing high K+ cells

1983 ◽  
Vol 73 (3) ◽  
pp. 247-256 ◽  
Author(s):  
P. K. Lauf
Keyword(s):  
Red Cells ◽  
Cl Transport ◽  
Sheep Red Cells ◽  
K Cells ◽  
High K

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)

Cl-dependent K transport in a pure population of volume-regulating human erythrocytes

1989 ◽  
Vol 256 (4) ◽  
pp. C858-C864 ◽  
Author(s):  
W. C. O'Neill
Keyword(s):  
Cell Volume ◽  
Regulatory Volume Decrease ◽  
Human Erythrocytes ◽  
Red Cells ◽  
Hypotonic Medium ◽  
K Cells ◽  
High K ◽  
The Relationship ◽  
Low K ◽  
Volume Decrease

Swelling of human red cells activates a putative K-Cl cotransport that is not present at normal cell volume and that disappears after several hours. To determine whether regulatory volume decrease (RVD) is occurring in human erythrocytes and is responsible for the inactivation of K-Cl cotransport, the relationship between cell volume and the inactivation and reactivation of volume-sensitive (VS) K-Cl cotransport was studied. VS K influx into high K cells was transient, whereas influx into low K cells (prepared with nystatin), which are unable to shrink via K efflux, remained fully activated. Likewise, VS K efflux into hypotonic medium disappeared after 100 min in a low K medium but remained activated in a high K medium that prevented cell shrinkage. Cells that had been preincubated in hypotonic medium to inactivate VS K-Cl cotransport showed no significant recovery of VS cotransport after a 6-h incubation in isotonic medium but showed full restoration of VS cotransport after treatment with nystatin in isotonic medium to reequilibrate cell water. A pure fraction of volume-regulating (VR) cells was subsequently isolated by preincubating red cells in hypotonic medium and then subjecting them to further hypotonicity to lyse all non-VR cells. The 2.5% of cells that remained consisted of 16% reticulocytes and exhibited a Cl-dependent RVD in hypotonic medium. VS K-Cl cotransport was enriched 10-fold and Na-K-Cl cotransport was enriched 12-fold in these cells, whereas the enrichment of N-ethylmaleimide (NEM)-activated K-Cl cotransport was only threefold.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Stimulation of the Potassium Transport System in Low Potassium Type Sheep Red Cells by a Specific Antigen Antibody Reaction

Nature ◽  
1969 ◽  
Vol 222 (5192) ◽  
pp. 477-478 ◽  
Author(s):  
J. C. ELLORY ◽  
ELIZABETH M. TUCKER
Keyword(s):  
Transport System ◽  
Specific Antigen ◽  
Potassium Transport ◽  
Red Cells ◽  
Sheep Red Cells ◽  
Low Potassium ◽  
Antibody Reaction ◽  
Antigen Antibody ◽  
Stimulation Of
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