scholarly journals The influence of external sodium ions on the sodium pump in erythrocytes

1968 ◽  
Vol 109 (3) ◽  
pp. 369-374 ◽  
Author(s):  
R. N. Priestland ◽  
R. Whittam
Keyword(s):  
Adenosine Triphosphatase ◽  
Sodium Pump ◽  
Erythrocyte Membranes ◽  
Sodium Ions ◽  
Adenosine Triphosphatase Activity ◽  
Sensitive Site ◽  
Na Efflux ◽  
Ion Movements ◽  
K Concentration ◽  
External K

1. A study has been made of the interaction between Na+ and K+ on the adenosine triphosphatase activity of erythrocyte ‘ghosts’, and on the K+ influx and Na+ efflux of intact erythrocytes. The adenosine triphosphatase activity and the ion movements were greater at a low external K+ concentration in the absence of Na+ than they were in the presence of 150mm-Na+. The inhibition by external Na+ of K+ influx had an inhibitory constant of 5–10mm. 2. Activation by K+ of kidney microsomal adenosine triphosphatase was retarded by Na+, and activation by Na+ was retarded by K+. Fragmented erythrocyte membranes behaved similarly. 3. These observations suggest that there is competition between Na+ and K+ at the K+-sensitive site of the membrane.

scholarly journals Ion Transport in Hydrodictyon africanum

1967 ◽  
Vol 50 (6) ◽  
pp. 1607-1625 ◽  
Author(s):  
J. A. Raven
Keyword(s):  
Free Energy ◽  
Low Temperature ◽  
Electrical Potential ◽  
Bathing Solution ◽  
Electrical Potential Difference ◽  
Energy Gradient ◽  
Na Efflux ◽  
K Concentration ◽  
Net Fluxes ◽  
External K

The concentrations of K, Na, and Cl in the cytoplasm and vacuole, the tracer fluxes of these ions into and out of the cenocyte, and the electrical potential difference between bathing solution and vacuole and cytoplasm, have been measured in Hydrodictyon africanum. If the ions were acted on solely by passive electrochemical forces, a net efflux of K and Cl and a net influx of Na would be expected. Tracer fluxes indicate a net influx of K and Cl and efflux of Na in the light; these net fluxes are consequently active, with an obligate link to metabolism. The effects of darkness and low temperature indicate that most of the tracer K and Cl influx and Na efflux are linked to metabolism, while the corresponding tracer fluxes in the direction of the free energy gradient are not. Ouabain specifically inhibits the metabolically linked portions of tracer K influx and Na efflux. Alterations in the external K concentration have similar effects on metabolically mediated K influx and Na efflux. It would appear that K influx and Na efflux are linked, at least in the light.

scholarly journals Strophanthidin-sensitive sodium fluxes in metabolically poisoned frog skeletal muscle.

1976 ◽  
Vol 68 (4) ◽  
pp. 405-420 ◽  
Author(s):  
B G Kennedy ◽  
P De Weer
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Human Erythrocyte ◽  
Sodium Pump ◽  
Giant Axon ◽  
Squid Giant Axon ◽  
Frog Skeletal Muscle ◽  
Na Efflux ◽  
Unidirectional Fluxes ◽  
External K

Strophanthidin-sensitive and insensitive unidirectional fluxes of Na were measured in fog sartorius muscles whose internal Na levels were elevated by overnight storage in the cold. ATP levels were lowered, and ADP levels raised, by metabolic poisoning with either 2,4-dinitrofluorobenzene or iodoacetamide. Strophanthidin-sensitive Na efflux and influx both increased after poisoning, while strophanthidin-insensitives fluxes did not. The increase in efflux did not require the presence of external K but was greatly attenuated when Li replaced Na as the major external cation. Membrane potential was not markedly altered by 2,4-dinitrofluorobenzene. These observations indicate that the sodium pump of frog skeletal muscle resembles that of squid giant axon and human erythrocyte in its ability to catalyze Na-Na exchange to an extent determined by intracellular ATP/ADP levels.

Decreased Ouabain-Sensitive Adenosine Triphosphatase Activity in the Erythrocyte Membrane of Patients with Chronic Renal Disease

1973 ◽  
Vol 45 (6) ◽  
pp. 775-784 ◽  
Author(s):  
C. H. Cole
Keyword(s):  
Renal Disease ◽  
Erythrocyte Membrane ◽  
Adenosine Triphosphatase ◽  
Chronic Renal Disease ◽  
Sodium Concentration ◽  
Erythrocyte Membranes ◽  
General Medical Ward ◽  
Adenosine Triphosphatase Activity ◽  
Average Decrease ◽  
Erythrocyte Sodium

1. Ouabain-sensitive ATPase (adenosine triphosphatase) activity was measured in the erythrocyte membranes of twenty patients with chronic renal disease. Decreased activity was found in nineteen of the twenty patients. The average decrease was 38%. 2. In three patients erythrocyte sodium concentration exceeded 9·5 mmol/l of RBC and these patients had the most marked decreases in ouabain-sensitive ATPase activity. 3. By contrast, in only two of 100 patients admitted to a general medical ward was erythrocyte sodium concentration greater than 9.5 mmol/l of RBC. 4. Ouabain-insensitive and calcium-activated components of erythrocyte membrane ATPase were unaffected by chronic renal disease.

The diffusion and electrogenic components of the membrane potential of hypoxic myocardium

1987 ◽  
Vol 65 (2) ◽  
pp. 246-251 ◽  
Author(s):  
Normand Leblanc ◽  
Elena Ruiz-Ceretti
Keyword(s):  
Membrane Potential ◽  
Sodium Pump ◽  
Resting Potential ◽  
Krebs Solution ◽  
Ventricular Muscle ◽  
Diffusion Component ◽  
K Concentration ◽  
Zero Potential ◽  
K Permeability ◽  
External K

The diffusion and electrogenic components of the resting potential of hypoxic ventricular muscle were separated by inhibition of the sodium pump with 10−4 M ouabain. The response to varying external K concentrations (Ko) was studied. Arteriaily perfused rabbit hearts were submitted to 60 min hypoxia in Krebs solution containing 5 mM K throughout or to different external K concentrations during the last 20 min of hypoxia. For K concentrations between 1.5 and 10 mM, hypoxia did not change the resting potential except for a slight hyperpolarization in 7.5 mM K. The diffusion component of the resting potential did not differ from the resting potential at Ko < 5 mM. An electrogenic potential of −3 to −6 mV was detectable at Ko values between 5 and 10 mM. The internal K concentration, Ki, was estimated from extrapolations to zero potential of the relation resting potential vs. Ko in normoxic and hypoxic hearts. These experiments revealed a decline of Ki of 16 mM with hypoxia. The variation of the diffusion potential with external K was fitted by a PNa:PK ratio five times lower than in normoxia. It has been concluded that an increase in K permeability and the persistence of electrogenic Na extrusion during hypoxia of rather short duration prevent membrane depolarization despite the myocardial K loss.

Increased sodium plus potassium adenosine triphosphatase activity in erythrocyte membranes in Huntington's disease

1978 ◽  
Vol 4 (1) ◽  
pp. 60-62 ◽  
Author(s):  
D. A. Butterfield ◽  
J. Q. Oeswein ◽  
M. E. Prunty ◽  
K. C. Hisle ◽  
W. R. Markesbery
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Adenosine Triphosphatase ◽  
Erythrocyte Membranes ◽  
Adenosine Triphosphatase Activity

Effects of Inhibitors of Active Transport on 22Na and 42K Movements and on Nucleotide Levels in Rat Uteri at 25 °C

1971 ◽  
Vol 49 (3) ◽  
pp. 178-204 ◽  
Author(s):  
E. E. Daniel ◽  
Kathleen Robinson
Keyword(s):  
Water Content ◽  
Sodium Pump ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Compartment Model ◽  
Sodium Influx ◽  
Na Pump ◽  
Cellular Fraction ◽  
Na Efflux ◽  
External K

The effects of inhibitors of the sodium pump (K-free solution or ouabain) on Na and K fluxes, water content, and adenine nucleotides were studied in rat uterine horns. The same four-compartment model [Formula: see text] was applied to K efflux as to Na efflux. However, for K efflux the larger cellular fraction, C, contained 70% of tissue K, and D could usually be ignored. K-free solutions did not alter ATP, ADP, or AMP levels, and had only small effects on efflux of Na from fresh or Na-rich tissues. In these tissues ouabain decreased Na efflux from the faster, larger cellular fraction (BK2 ↓) without affecting adenine nucleotide levels. K-free solutions or ouabain increased sodium influx, but neither inhibitor caused swelling. The inhibitors decreased water content of fresh tissues and failed to interfere with extrusion of water accompanying Na from Na-rich tissues. In addition to the ouabain-sensitive pump, another Na pump insensitive to K levels or ouabain was postulated to be responsible for control of cell volume and part of Na efflux in uteri. The K efflux was increased by ouabain, but not by K-free solutions. The K influx was decreased by K-free solutions, but was not affected by ouabain. Increasing external K (concentrations of 18.4 mM and higher) did not diminish the effects of ouabain on Na or K efflux. Neither cocaine nor adrenaline prevented the effect of ouabain on the Na or K efflux or on the increased Na influx. No evidence was obtained that a Na exchange–diffusion system operated in K-free solutions. It was concluded that the accepted views about the operation of a Na pump involving (Na+ + K+)-activated, ouabain-sensitive ATPase have to be modified for rat uteri.

Sign in / Sign up

Export Citation Format

Share Document