A comparison of endogenous digoxin-like immunoreactivity and sodium transport inhibitory activity in umbilical arterial and venous serum

1988 ◽  
Vol 75 (6) ◽  
pp. 577-579 ◽  
Author(s):  
J. F. Morris ◽  
L. Poston ◽  
C. D. Wolfe ◽  
P. J. Hilton
Keyword(s):  
Umbilical Cord ◽  
Rate Constant ◽  
Sodium Transport ◽  
Inhibitory Activity ◽  
Efflux Rate ◽  
Sodium Efflux ◽  
Cord Serum ◽  
Paired Samples ◽  
Efflux Rate Constant

1. Endogenous digoxin-like immunoreactivity (EDLI) was measured by radioimmunoassay for digoxin in 13 paired samples of arterial and venous umbilical cord serum. EDLI was present in vein and artery, but was higher in the venous samples (P < 0.025). 2. The venous cord serum inhibited the ouabain-sensitive sodium efflux rate constant of a normal mixed leucocyte population when compared with the effect of arterial cord serum (P < 0.005). 3. It is suggested that the placenta may be involved in the production or metabolism of neonatal EDLI and of the inhibitor of sodium transport.

A Passive Sodium Transport Inhibitory Factor (Inhibitin) Released from Leukaemic Promyelocytes in Culture

1984 ◽  
Vol 66 (3) ◽  
pp. 365-368
Author(s):  
Kevin Morgan ◽  
M. Afzal Mir
Keyword(s):  
Rate Constant ◽  
Sodium Transport ◽  
Culture Media ◽  
Inhibitory Effect ◽  
Inhibitory Factor ◽  
Efflux Rate ◽  
Sodium Efflux ◽  
Stable Factor ◽  
Heat Stable ◽  
Efflux Rate Constant

1. Previous studies have shown that myeloid leukaemic blast cells contain a heat stable factor which inhibits bidirectional sodium transport in normal erythrocytes. This study was undertaken to establish whether leukaemic promyelocytes in culture secrete this factor. 2. Two cell-lines of leukaemic promyelocytes (HL-60 and JR) were grown and culture media from both reduced significantly the ouabain-insensitive sodium efflux rate constant, whereas conditioned culture medium (incubated like the cells in culture) had no inhibitory effect. 3. Promyelocyte extract reduced significantly (P < 0.01) the total sodium efflux rate constant from 0.393 ± 0.030 (sd) to 0.311 ± 0.060, and ouabain-insensitive efflux rate constant from 0.131 ± 0.008 to 0.079 ± 0.009 (P<0.001). 4. The inhibitory factor was heat stable (80°C for 30 min) and it inhibited sodium efflux through a pathway which was not inhibited by ouabain or frusemide. 5. These studies suggest that leukaemic promyelocytes secrete the previously identified passive sodium transport inhibitory factor.

Effect of Acute and Chronic Salt Loading on Erythrocyte 22Na Efflux in Males with Essential Hypertension

1981 ◽  
Vol 61 (s7) ◽  
pp. 37s-39s ◽  
Author(s):  
J. B. Myers ◽  
W. R. Fitzgibbon ◽  
T. O. Morgan
Keyword(s):  
Essential Hypertension ◽  
Rate Constant ◽  
Sodium Transport ◽  
Sodium Intake ◽  
Efflux Rate ◽  
Natriuretic Hormone ◽  
Salt Loading ◽  
Sodium Efflux ◽  
Plasma Factor ◽  
Efflux Rate Constant

1. Present results confirm our previous work which showed that a sodium intake over 3 mmol day−1 kg−1 decreased the total erythrocyte efflux rate constant in untreated males with essential hypertension. 2. The infusion of saline (2.25 mmol of Na+/kg) over 30 min decreased the efflux rate constant. 3. The change after chronic sodium loading and the intravenous infusion of saline is in the ouabain-sensitive component (ouabain-sensitive Na+, K+ ATPase pump activity) of total efflux. 4. The reduction in efflux by an acute sodium load occurred only when chronic sodium intake was low. 5. Posture did not affect the efflux rate constant whether sodium intake was high or low. 6. The reduction in efflux after chronic ingestion and acute administration of sodium occurred only when erythrocytes were incubated in plasma. It did not occur in artificial medium, which suggested that a plasma factor mediated the effect of added sodium on cell sodium efflux. 7. The effect of sodium on cell sodium transport by a plasma factor with ouabain-like properties (which may be a natriuretic hormone) constitutes a regulatory system. This system, the sodium-ouabain-vsensitive cell sodium-transport pathway system, has important implications for the understanding of blood pressure control and sodium homeostasis.

Evidence for an inhibitor of leucocyte sodium transport in the serum of neonates

1987 ◽  
Vol 73 (3) ◽  
pp. 291-297 ◽  
Author(s):  
J. F. Morris ◽  
M. D. McEachern ◽  
L. Poston ◽  
S. E. Smith ◽  
M. J. Mulvany ◽  
...  
Keyword(s):  
Rate Constant ◽  
Sodium Transport ◽  
Normal Subjects ◽  
High Concentration ◽  
Third Trimester ◽  
Sodium Efflux ◽  
Cord Serum ◽  
Resistance Vessels ◽  
Control Serum ◽  
Efflux Rate Constant

1. In confirmation of previous studies, serum obtained from cord blood demonstrated endogenous digoxin-like immunoreactivity (EDLI). Sera from pregnant women in the third trimester also demonstrated EDLI, which disappeared after delivery. 2. Cord serum inhibited the total sodium efflux rate constant of a mixed leucocyte preparation when compared with the effect of control serum. This inhibition resulted from a depression of the ouabain-sensitive (sodium pump) component of the rate constant. 3. An ultrafiltrate of the serum (mol. wt. < 30 000) also inhibited ouabain-sensitive leucocyte sodium transport when compared with filtrate obtained from control serum. 4. DHA-S Dehydroepiandrosterone sulphate (DHA-S) and cortisone, both present in high concentration in cord serum, demonstrated EDLI but did not affect leucocyte sodium transport in the cells of normal subjects. 5. DHA-S had no effect on sodium transport or vasoconstrictor activity in human omental resistance vessels. 6. It is concluded that EDLI of cord serum is associated with sodium transport inhibitory activity. This is unlikely to be attributable to DHA-S or cortisone.

Studies of Sodium Transport in Thymocytes of Rats with DOC/Salt Hypertension

1982 ◽  
Vol 63 (s8) ◽  
pp. 65s-67s ◽  
Author(s):  
R. B. Jones ◽  
J. Patrick ◽  
P. J. Hilton
Keyword(s):  
Rate Constant ◽  
Sodium Transport ◽  
Dry Weight ◽  
Sodium Content ◽  
Intracellular Sodium ◽  
Control Group ◽  
Efflux Rate ◽  
Sodium Influx ◽  
Sodium Efflux ◽  
Efflux Rate Constant

1. Sodium transport and intracellular sodium content were studied in thymocytes of rats made hypertensive by treatment for 4 or 8 weeks with deoxycorticosterone (DOC) and salt (DOC/salt). 2. The systolic blood pressure in the DOC/salt animals was 152 ± sem 3 and 189 ± 3 mmHg after 4 and 8 weeks' treatment respectively. This was significantly higher than pressures in their respective controls (124 ± 4 and 126 ± 5 mmHg), which had been given 1% sodium chloride solution (171 mmol/l) only. 3. The total sodium efflux rate constant in the DOC/salt rats was lower than that in the control group after 8 weeks of treatment (5.56 ± sem 0.21 vs 6.12 ± 0.11 h−1; P < 0.05) but not after 4 weeks of treatment (5.93 ± 0.13 vs 6.32 ± 0.13 h−1;0.1 > P > 0.05). 4. Intracellular sodium content in the DOC/salt rats was significantly higher than that of the control animals after 8 weeks' treatment (49.6 ± 2.5 vs 42.1 ± 1.0 mmol/kg dry weight; P < 0.05). 5. No significant changes were observed in intracellular potassium content, sodium influx or ouabain-insensitive sodium efflux rate constant.

Erythrocyte 22Na Efflux and Urinary Sodium Excretion in Essential Hypertension

1980 ◽  
Vol 59 (s6) ◽  
pp. 195s-197s ◽  
Author(s):  
W. R. Fitzgibbon ◽  
T. O. Morgan ◽  
J. B. Myers
Keyword(s):  
Rate Constant ◽  
Sodium Excretion ◽  
Urinary Sodium Excretion ◽  
Urinary Sodium ◽  
Aetiological Factor ◽  
Efflux Rate ◽  
Artificial Medium ◽  
Sodium Efflux ◽  
Hypertensive Patients ◽  
Efflux Rate Constant

1. The rate constant for total 22Na efflux from erythrocytes was examined in patients with mild to moderate hypertension and in normotensive controls. No difference in 22Na efflux rate constant was found when the cells from both groups were incubated in artificial medium. When the cells from both groups were incubated in their own plasma, the rate constant for Na efflux was significantly elevated for hypertensive patients compared with controls (0.40 ± 0.02, 0.36 ± 0.01 respectively; P&lt;0.05). 2. In hypertensive patients sodium efflux rate constant varied inversely with 24 h urinary sodium excretion when erythrocytes were incubated in artificial medium (r = − 0.34, P&lt;0.05) or in plasma (r = −0.42, P&lt;0.05). No association between sodium efflux rate constant and urinary sodium excretion occurred in normotensive subjects. 3. These findings provide further evidence that sodium is an important aetiological factor in hypertension. In ‘salt-sensitive’ individuals dietary sodium may interact with the regulation of cellular sodium transport via both humoral and cellular mechanisms to elevate blood pressure.

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 Relation between Membrane Cholesterol and Phospholipid and Sodium Efflux in Erythrocytes from Healthy Subjects and Patients with Chronic Cholestasis

1982 ◽  
Vol 62 (1) ◽  
pp. 101-107 ◽  
Author(s):  
P. A. Jackson ◽  
D. B. Morgan
Keyword(s):  
Rate Constant ◽  
Healthy Subjects ◽  
Sodium Content ◽  
Molar Ratio ◽  
Phospholipid Content ◽  
Efflux Rate ◽  
Sodium Efflux ◽  
Chronic Cholestasis ◽  
Efflux Rate Constant ◽  
Erythrocyte Sodium

1. The cholesterol and phospholipid content of the cell membrane and the efflux of sodium were measured in the erythrocytes of patients with chronic cholestasis and in healthy subjects. 2. The membranes from the patients contained more cholesterol and phospholipid and had a higher cholesterol/phospholipid molar ratio than the membranes from the healthy subjects. 3. The sodium efflux rate constant was reduced in the patients and this was entirely due to a reduction in the frusemide-sensitive efflux rate constant. There was no difference in either the ouabain-sensitive or the ouabain plus frusemide-resistant rate constants. 4. This reduction in the frusemide-sensitive rate constant was associated with a reduction in the erythrocyte sodium content. 5. When erythrocytes were loaded with cholesterol in vitro the frusemide-sensitive efflux rate constant was reduced by an amount similar to that observed in the patients. In addition, however, there was a reduction in the ouabain-sensitive efflux rate constant and an increase in the erythrocyte sodium content; neither of these changes was observed in the patients in vivo.

Erythrocytic ouabain-sensitive sodium efflux rate constant in pregnancy

1993 ◽  
Vol 48 (3) ◽  
pp. 177-181
Author(s):  
Marion A.L. Didden ◽  
Jos H.A. Vollebergh ◽  
Marcel P. Hoekstra ◽  
Andries Schellekens ◽  
Pieter A. de Jong
Keyword(s):  
Rate Constant ◽  
Efflux Rate ◽  
Sodium Efflux ◽  
Efflux Rate Constant ◽  
In Pregnancy

Changes in the Number and Activity of Sodium Pumps in Erythrocytes from Patients with Hyperthyroidism

1983 ◽  
Vol 64 (4) ◽  
pp. 441-447 ◽  
Author(s):  
E. Jill Rubython ◽  
M. Cumberbatch ◽  
D. B. Morgan
Keyword(s):  
Rate Constant ◽  
Binding Capacity ◽  
Zinc Content ◽  
Sodium Content ◽  
Efflux Rate ◽  
Ouabain Binding ◽  
Sodium Efflux ◽  
Sodium Pumps ◽  
Efflux Rate Constant ◽  
Hyperthyroid Patients

1. The sodium content, the rate and rate constant of ouabain-sensitive sodium efflux and the number of sodium pumps (indicated by the ouabain-binding capacity) were measured in erythrocytes from patients with hyperthyroidism and compared with values obtained in euthyroid patients and healthy control subjects. Erythrocyte zinc content was measured as a simple estimate of the content of carbonic anhydrase. 2. In the hyperthyroid patients, erythrocyte sodium content was increased, whereas the rate and rate constant of ouabain-sensitive sodium efflux, the ouabain-binding capacity and erythrocyte zinc content were all decreased. 3. The sodium pumps in hyperthyroidism had the same affinity for ouabain and the same rate constant per pump as those in healthy controls. 4. The decrease in the efflux rate constant could be entirely accounted for by the decrease in the number of sodium pumps. 5. Although the sodium efflux was decreased in the hyperthyroid patients, the change was less than expected for the decrease in the efflux rate constant. This suggests that there is an increase in the ground permeability of the erythrocyte membrane in hyperthyroidism. 6. In the hyperthyroid patients the number of sodium pumps and erythrocyte zinc content were inversely related to the plasma levels of thyroxine and tri-iodothyronine, but more closely to the latter. 7. These results suggest that the thyroid hormones may influence the erythrocyte's content of a range of proteins which happens to include the sodium pump.

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