Observations on the Measurement and Regulation of the Sodium Content of Rabbit Erythrocytes: Evidence for a Single Sodium Pump

1972 ◽  
Vol 50 (8) ◽  
pp. 791-797 ◽  
Author(s):  
E. K. M. Smith ◽  
D. Farrington ◽  
L. Sydiuk
Keyword(s):  
Rate Constant ◽  
Sodium Pump ◽  
Ethacrynic Acid ◽  
Sodium Content ◽  
Red Cells ◽  
Red Cell ◽  
Sodium Efflux ◽  
A Value ◽  
Active Transport Mechanism ◽  
Sodium Dependent

We have studied the cation content of rabbit erythrocytes; for a group of 40 animals red cell sodium was 9.2 ± 2.7 (S.D.) mmol/1 of cells, while potassium was 112 ± 8.6 mmol/1. Cell sodium content rose as the animals aged, but there was always a wide concentration gradient across the cell wall. This gradient was maintained by an active sodium pump, inhibited by ouabain (10−4 M) and comparable to pump I in the human red cell. The rate constant for this process in 16 rabbits was 0.313 ± 0.07 (S.D.) h−1, a value similar to that seen in man. Ethacrynic acid (10−3 M) inhibited a further component of sodium efflux, the rate constant being 0.259 ± 0.015 (S.D.) h−1. This was superficially comparable to pump II as previously described in the human; on further study, however, it was found to be sodium dependent, but able to function in the absence of adenosine triphosphate and incapable of net up-hill transport. These findings indicate that there is only one active transport mechanism in the red cells of the rabbit, which is a useful model for study in comparison to the red cells of man.

scholarly journals Changes from High Potassium (HK) to Low Potassium (LK) in Bovine Red Cells

1972 ◽  
Vol 59 (3) ◽  
pp. 270-284 ◽  
Author(s):  
Yedy Israel ◽  
Alain Macdonald ◽  
Jaime Bernstein ◽  
Eduardo Rosenmann
Keyword(s):  
Adenosine Triphosphatase ◽  
Sodium Content ◽  
Red Cells ◽  
Red Cell ◽  
Transport Capacity ◽  
High Potassium ◽  
A Value ◽  
Low Potassium ◽  
Newborn Calves ◽  
Time Required

Red cells of newborn calves contain 105–110 mmole K+ and 1–5 mmole Na+ per liter of cells. As the animals age the K+ content decreases to a value of 25–30 mmole/liter of cells after about 60 days. At approximately the same time, the sodium content reaches a value of 60–70 mmole/liter. The time required for half change (t½) is 35–37 days for both Na+ and K+. The activity of (Na + K)-adenosine triphosphatase (ATPase) and the influx of K42 and Rb86 into the red cells are high at birth and are reduced to 5 and 15% of their original values, respectively, in mature animals. t½ for both is of the order of 30–35 days. The membrane Mg-ATPase activity is also high at birth and is reduced with a t½ of 28–32 days to a final value of about 20% of its activity at birth. Separation of red cells according to their age showed that, in animals at the age of transition, newly formed red cells contain a higher K/Na ratio and a higher active transport capacity than older red cells of the same animal. It is suggested that the changes observed are a reflection of the average age of the red cell population as the animal grows.

Red Cell Glutathione in Anaemia

1973 ◽  
Vol 18 (6) ◽  
pp. 177-181 ◽  
Author(s):  
J. Hopkins ◽  
G. R. Tudhope
Keyword(s):  
Inverse Relationship ◽  
Reduced Glutathione ◽  
Haemoglobin Concentration ◽  
Normal Subjects ◽  
Initial Therapy ◽  
Megaloblastic Anaemia ◽  
Red Cells ◽  
Red Cell ◽  
A Value ◽  
Normal Mean

Erythrocyte reduced glutathione (GSH) has been measured in 17 normal subjects and in 70 patients with anaemia of various causes; the red cells of most of the anaemic patients contained abnormally high levels of GSH. In the group of cases of untreated megaloblastic anaemia in which the haemoglobin concentration was less than 8.0 g. per 100 ml., there was an inverse relationship between the erythrocyte GSH level and the haemoglobin concentration. During initial therapy in megaloblastic anaemia, as the haemoglobin concentration increased, the GSH level decreased towards normal; the time taken for the GSH level to reach a value 2 standard deviations above the normal mean was inversely related to the initial haemoglobin concentration. In the red cells of patients with anaemia there was no correlation between the GSH level and the activity of glutathione peroxidase. The significance of these findings is discussed.

Leucocyte Electrolytes and Sodium Efflux Rate Constants in the Hypertension of Pre-Eclampsia

1980 ◽  
Vol 59 (s6) ◽  
pp. 199s-201s ◽  
Author(s):  
T. E. Forrester ◽  
G. A. O. Alleyne
Keyword(s):  
Blood Pressure ◽  
Rate Constant ◽  
Rate Constants ◽  
Sodium Pump ◽  
Efflux Rate ◽  
Sodium Efflux ◽  
Pump Activity

1. Leucocyte electrolytes were measured in pre-eclampsia and comparison was made with leucocytes from normal primigravidae and from the original pre-eclamptic subjects 6 months after delivery when blood pressure had returned to normal. 2. In pre-eclamptic subjects, leucocyte sodium was elevated and potassium depressed, and the rate constant for sodium efflux was depressed. 3. These changes returned to normal after delivery. 4. An increase in cellular sodium as a result of altered sodium pump activity may be the cause of hypertension in pre-eclampsia.

The Efflux of Sodium from Single Crab Muscle Fibres

1967 ◽  
Vol 47 (3) ◽  
pp. 709-721 ◽  
Author(s):  
E. E. Bittar ◽  
P. C. Caldweix ◽  
A. G. Lowe
Keyword(s):  
Normal Level ◽  
Sodium Pump ◽  
Muscle Fibres ◽  
Single Muscle ◽  
Sodium Efflux ◽  
Leg Muscles ◽  
A Value ◽  
External Potassium ◽  
Radioactive Sodium ◽  
Lactate And Pyruvate

The efflux of radioactive sodium injected into single muscle fibres from the leg muscles of Maia squinado (Herbst) has been studied. The efflux is reduced by the sodium-pump-inhibitor ouabain and by removal of the external potassium. An increase in external potassium leads to a transient increase in sodium efflux which is then followed by a decline to a value well below the normal level. Externally applied caffeine and injected calcium can, under certain conditions, cause a lowering of the sodium efflux which may be associated with contraction of the fibre. The injection of lactate and pyruvate did not affect the efflux. The results are discussed in terms of the possible effects of the structure of the fibre on the efflux.

Abnormalities in the Sodium Pump of Erythrocytes from Patients with Hyperthyroidism

1970 ◽  
Vol 38 (1) ◽  
pp. 49-61 ◽  
Author(s):  
E. K. M. Smith ◽  
Pamela D. Samuel
Keyword(s):  
Sodium Pump ◽  
Sodium Concentration ◽  
Intracellular Sodium ◽  
Red Cells ◽  
Control Group ◽  
Active Sodium ◽  
Sodium Efflux ◽  
Control Subjects ◽  
Intracellular Sodium Concentration ◽  
The Mean

1. Intracellular cation composition has been measured in the red cells from twenty patients with hyperthyroidism. The mean concentration of sodium was 11·18 m-mole/l red cells; in sixty normal control subjects the mean red cell sodium level was 7·04 m-mole/l. The difference between these two groups was highly significant. There was no measurable difference between the potassium concentration and water content of red cells from thyrotoxic and control groups. 2. Measurements of active sodium efflux were carried out in red cells from ten hyperthyroid subjects and their matched controls. The rate constant for active sodium efflux was significantly lower in the patients than the control group. 3. The total amount of sodium actively pumped from red cells in 1 hr was significantly higher in the patients than the controls. 4. The total amount of sodium moving out of the red cells, both actively and by exchange diffusion, matched the total influx of sodium. This was true for control subjects and those with hyperthyroidism and this would support the view that the intracellular sodium concentration is constant and represents the result of a balance between influx and efflux. In hyperthyroidism this balance persists, but with an abnormally high intracellular sodium concentration. 5. There was a linear relationship between the cell sodium content and the active transport of sodium from the cell in control and hyperthyroid subjects. 6. Triiodothyronine did not produce any change in sodium transport by normal red cells in vitro. 7. It is concluded that there is a depression of the activity of the sodium pump in the red cells of hyperthyroid subjects. This allows the resting intracellular sodium concentration to rise until a new steady state is reached. Evidence is given that these changes are reversed when hyperthyroidism is corrected.

A Serial Study of Erythrocyte Sodium Content and Sodium Pump Kinetics in Pregnancy

1990 ◽  
Vol 79 (6) ◽  
pp. 631-638 ◽  
Author(s):  
S. MacPhail ◽  
T. H. Thomas ◽  
R. Wilkinson ◽  
J. M. Davison ◽  
W. Dunlop
Keyword(s):  
Rate Constant ◽  
Whole Blood ◽  
Sodium Pump ◽  
Maximum Velocity ◽  
Sodium Content ◽  
Affinity Constant ◽  
Pump Rate ◽  
Erythrocyte Sodium ◽  
Sodium Pump Inhibition

1. Normotensive primigravid pregnant women were studied longitudinally during pregnancy and 20 weeks after delivery. 2. Erythrocyte sodium content, ouabain-sensitive sodium flux and sodium pump rate constant were measured in whole blood, and the maximum velocity and sodium affinity of the sodium pump were measured in vitro. 3. Erythrocyte sodium content decreased and the sodium pump rate constant increased up to 26 weeks gestation. The increase in rate constant was due to an increase in the affinity of the sodium pump for sodium up to 20 weeks gestation. After 20 weeks gestation there was an increase in maximum velocity and a decrease in sodium affinity of the sodium pump but no further change in the sodium pump rate constant. 4. At 14 weeks gestation the sodium pump rate constant was correlated with both the maximum velocity and sodium affinity constant. After this time the relationship was much more variable and there was no correlation with the sodium affinity constant. The comparison of measurements of the sodium pump in whole blood and in vitro gave no evidence of sodium pump inhibition. 5. The erythrocyte sodium pump changed throughout gestation with different components to the change, but, overall, available sodium pump activity in blood increased and sodium content decreased.

Ouabain-Resistant, Frusemide-Sensitive Sodium Efflux in Human Lymphocytes: A Comparison of Normotensive and Hypertensive Subjects

1984 ◽  
Vol 67 (4) ◽  
pp. 407-411 ◽  
Author(s):  
A. Montanari ◽  
Isabella Simoni ◽  
E. Sani ◽  
P. Schianchi ◽  
A. Borghetti ◽  
...  
Keyword(s):  
Rate Constant ◽  
Human Lymphocytes ◽  
Sodium Content ◽  
Peripheral Blood Lymphocytes ◽  
Free Medium ◽  
Transport Pathway ◽  
Sodium Efflux ◽  
Low Sodium ◽  
Efflux Rate Constant ◽  
Cotransport System

1. Peripheral blood lymphocytes were isolated at room temperature in a low sodium medium in 17 normotensive control subjects (NC) and 13 patients with essential hypertension (EHP). 2. Lymphocyte sodium content was not significantly different between NC and EHP (3.1 ± 0.5, n = 11, and 3.6 ± 0.5, n = 10, respectively; means ± sem). 3. The effect of frusemide on the ouabain-resistant rate constant of sodium efflux (KNao) from these lymphocytes into a sodium-free medium was measured. 4. The frusemide-sensitive efflux rate constant was 75 ± 5 μs (n = 17) in controls and significantly lower in EHP (32 ± 7 μs, n = 13, P<0.001). 5. In human lymphocytes there is a ouabain-resistant, frusemide-sensitive fraction of sodium efflux into a sodium-free medium; this fraction may be reasonably attributed to a sodium-potassium cotransport system. This sodium transport pathway seems to be reduced in lymphocytes from EHP.

A Study In Vitro of the Sodium Pump in Fulminant Hepatic Failure

1978 ◽  
Vol 55 (4) ◽  
pp. 355-363 ◽  
Author(s):  
A. N. Alam ◽  
Lucilla Poston ◽  
S. P. Wilkinson ◽  
C. G. Golindano ◽  
R. Williams
Keyword(s):  
Fulminant Hepatic Failure ◽  
Hepatic Failure ◽  
Sodium Pump ◽  
Normal Subjects ◽  
Sodium Content ◽  
Atp Content ◽  
Efflux Rate ◽  
Sodium Efflux ◽  
Reduced Activity

1. The mechanism underlying the raised leucocyte sodium content in fulminant hepatic failure was studied by measurement of sodium fluxes, (Na+ + K+)-dependent adenosine triphosphatase activity, and leucocyte ATP content. 2. The rate constant for sodium efflux in the leucocytes was significantly reduced, and attributable to reduced activity of the enzyme (Na+ + K+)-ATPase. Leucocyte ATP content was not significantly different from that of control cells. 3. Incubation of cells from patients in the sera of normal subjects resulted in a reversal of these changes. Inhibition of the leucocyte sodium efflux rate constants and (Na+ + K+)-ATPase of normal cells was achieved by incubation in sera from patients. 4. We suggest that the raised sodium content of leucocytes in fulminant hepatic failure is attributable to a defective sodium pumping mechanism, possibly due to a circulating toxin.

Effect of Hypokalaemia on the Ouabain-Sensitive Sodium Transport and the Ouabain-Binding Capacity in Human Erythrocytes

1983 ◽  
Vol 64 (2) ◽  
pp. 177-182 ◽  
Author(s):  
E. Jill Rubython ◽  
D. B. Morgan
Keyword(s):  
Rate Constant ◽  
Binding Capacity ◽  
Plasma Potassium ◽  
Inhibitory Effect ◽  
Sodium Content ◽  
Efflux Rate ◽  
Ouabain Binding ◽  
Sodium Efflux ◽  
Sodium Pumps ◽  
Efflux Rate Constant

1. The sodium content, the ouabain-sensitive sodium efflux and efflux rate constant and the ouabain-binding capacity were measured in the erythrocytes of 53 patients with hypokalaemia and in 37 healthy controls. The sodium content alone was measured in a further 57 patients with hypokalaemia. 2. In the patients with hypokalaemia there was an increase in the average sodium content of the erythrocytes, which was entirely due to a reduction in the ouabain-sensitive efflux rate constant. 3. The ratio of the ouabain-sensitive efflux rate constant to the number of sodium pumps was decreased in the patients with hypokalaemia, and was directly related to the plasma potassium. 4. Many patients with moderate hypokalaemia had normal erythrocyte sodium and potassium contents and normal ouabain-sensitive efflux rate constant. These patients had an increased number of sodium pumps, which compensated for the inhibitory effect of hypokalaemia on each sodium pump. 5. This increase in the number of sodium pumps was common even in patients who had probably had hypokalaemia for less than 2 weeks. This finding suggests that there are latent sodium pumps within the circulating erythrocytes.

The Relationship of Membrane ATPase Activity to Ouabain-Insensitive Sodium Transport in Human Red Cells

1973 ◽  
Vol 51 (9) ◽  
pp. 642-648 ◽  
Author(s):  
E. K. M. Smith ◽  
L. G. Welt
Keyword(s):  
Ethacrynic Acid ◽  
Diffusion Mechanism ◽  
Red Cell ◽  
Active Sodium ◽  
Sodium Efflux ◽  
Membrane Atpase ◽  
Active Transport System ◽  
Relationship Of ◽  
The Relationship ◽  
Human Red Cells

A component of active sodium efflux has been described by Hoffman and Kregenow (1966, Ann. N.Y. Acad. Sci. 137, 566–567) which is not inhibited by ouabain but is inhibited by ethacrynic acid. This has been called "Pump II" and these authors have produced evidence suggesting that the process does not require adenosine triphosphate (ATP) for its energy supply. Studies of membrane adenosine triphosphatase (ATPase) from human erythrocytes have therefore been carried out to determine if any component of this enzyme behaved in a qualitatively similar way to that of "Pump II." Our results have shown that ethacrynic acid behaved like a nonspecific sulfhydryl-reacting substance with no discrete inhibitory properties. Two analogues of ethacrynic acid, which did not have any sulfhydryl-reacting properties, could also inhibit "Pump II" but did not inhibit membrane ATPase.It is concluded that there is no direct qualitative correlation between "Pump II" and membrane ATPase in the human red cell. This supports the view that "Pump II" functions independently of the activity of membrane ATPase. Whether "Pump II" is an active transport system or part of a cation exchange diffusion mechanism, it is unlikely that ATP or membrane ATPase are concerned in its function.

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