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Sodium

About: Sodium is a(n) research topic. Over the lifetime, 68944 publication(s) have been published within this topic receiving 1208422 citation(s). The topic is also known as: element 11 & natrium.
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Journal ArticleDOI
TL;DR: The identity of the ions which carry the various phases of the membrane current is chiefly concerned with sodium ions, since there is much evidence that the rising phase of the action potential is caused by the entry of these ions.
Abstract: In the preceding paper (Hodgkin, Huxley & Katz, 1952) we gave a general description of the time course of the current which flows through the membrane of the squid giant axon when the potential difference across the membrane is suddenly changed from its resting value, and held at the new level by a feed-back circuit ('voltage clamp' procedure). This article is chiefly concerned with the identity of the ions which carry the various phases of the membrane current. One of the most striking features of the records of membrane current obtained under these conditions was that when the membrane potential was lowered from its resting value by an amount between about 10 and 100 mV. the initial current (after completion of the quick pulse through the membrane capacity) was in the inward direction, that is to say, the reverse ofthe direction of the current which the same voltage change would have caused to flow in an ohmic resistance. The inward current was of the right order of magnitude, and occurred over the right range of membrane potentials, to be the current responsible for charging the membrane capacity during the rising phase of an action potential. This suggested that the phase of inward current in the voltage clamp records might be carried by sodium ions, since there is much evidence (reviewed by Hodgkin, 1951) that the rising phase of the action potential is caused by the entry of these ions, moving under the influence of concentration and potential differences. To investigate this possibility, we carried out voltage clamp runs with the axon surrounded by solutions with reduced sodium concentration. Choline was used as an inert cation since replacement of sodium with this ion makes the squid axon completely inexcitable, but does not reduce the resting potential (Hodgkin & Katz, 1949; Hodgkin, Huxley & Katz, 1949).

2,181 citations


Journal ArticleDOI
20 Aug 1999-Science
TL;DR: Overexpression of a vacuolar Na+/H+ antiport fromArabidopsis thaliana in Arabidopsis plants promotes sustained growth and development in soil watered with up to 200 millimolar sodium chloride, demonstrating the feasibility of engineering salt tolerance in plants.
Abstract: Agricultural productivity is severely affected by soil salinity. One possible mechanism by which plants could survive salt stress is to compartmentalize sodium ions away from the cytosol. Overexpression of a vacuolar Na+/H+antiport from Arabidopsis thaliana in Arabidopsisplants promotes sustained growth and development in soil watered with up to 200 millimolar sodium chloride. This salinity tolerance was correlated with higher-than-normal levels of AtNHX1transcripts, protein, and vacuolar Na+/H+(sodium/proton) antiport activity. These results demonstrate the feasibility of engineering salt tolerance in plants.

1,782 citations


Journal ArticleDOI
Jens Chr. Skou1
TL;DR: Leg nerves from the shore crab contain an adenosine triphosphatase which is located in the submicroscopic particles, and the influence of sodium, potassium, magnesium and calcium ions on this enzyme has been investigated.
Abstract: Leg nerves from the shore crab (Carcinus maenas) contain an adenosine triphosphatase which is located in the submicroscopic particles. The influence of sodium, potassium, magnesium and calcium ions on this enzyme has been investigated. The presence of magnesium ions is an obligatory requirement for the activity of the enzyme. Sodium ions increase the activity when magnesium ions are present. Potassium ions increase the activity when the system contains both magnesium and sodium ions. Potassium ions in high concentration inhibit that part of the activity which is due to Na+, while the activity due to Mg++ is not affected. Calcium ions inhibit the enzyme under all conditions. When Mg++ or Mg++ + Na+ are present in the system, the optimum magnesium concentration is equal to the concentration of ATP. If potassium ions are added, the optimum magnesium concentration is doubled. If calcium ions are also added, the optimum magnesium concentration becomes still higher, and it increases with the calcium concentration. A majority of these observations may be explained by assuming (a) that the substrate most readily attacked by the enzyme is sodium-magnesium-ATP, (b) that potassium ions stimulate the enzyme directly, and (c) that an increase in the concentration of potassium ions leads to a displacement of sodium ions from the substrate and accordingly to an inhibition of the reaction. If the system contains the four cations in concentrations roughly equal to those in the crab-nerve axoplasm, an increase in the sodium concentration as well as a decrease in the potassium concentration will lead to an intensification of the enzyme activity. This observation, as well as some other characteristics of the system, suggest that the adenosine triphosphatase studied here may be involved in the active extrusion of sodium from the nerve fibre.

1,761 citations


Journal ArticleDOI
TL;DR: It is concluded that the urine from the subjects when salt-loaded contains a natriuretic substance.
Abstract: Effect of urinary extracts from salt loaded man on urinary sodium excretion of the rat. Urinary extracts prepared from subjects on low and high intakes of sodium chloride were injected into conscious water-loaded rats. Urinary extracts obtained from the subjects when salt-depleted did not cause a significant rise in urinary sodium excretion or urine flow. Urinary extracts obtained from the subjects when salt-loaded caused a significant rise in urinary sodium excretion and urine flow. It is concluded that the urine from the subjects when salt-loaded contains a natriuretic substance.

1,756 citations


Journal ArticleDOI
Jens Chr. Skou1
Abstract: Leg nerves from the shore crab (Carcinus maenas) contain an adenosine triphosphatase which is located in the submicroscopic particles. The influence of sodium, potassium, magnesium and calcium ions on this enzyme has been investigated. The presence of magnesium ions is an obligatory requirement for the activity of the enzyme. Sodium ions increase the activity when magnesium ions are present. Potassium ions increase the activity when the system contains both magnesium and sodium ions. Potassium ions in high concentration inhibit that part of the activity which is due to Na+, while the activity due to Mg++ is not affected. Calcium ions inhibit the enzyme under all conditions. When Mg++ or Mg++ + Na+ are present in the system, the optimum magnesium concentration is equal to the concentration of ATP. If potassium ions are added, the optimum magnesium concentration is doubled. If calcium ions are also added, the optimum magnesium concentration becomes still higher, and it increases with the calcium concentration. A majority of these observations may be explained by assuming (a) that the substrate most readily attacked by the enzyme is sodium-magnesium-ATP, (b) that potassium ions stimulate the enzyme directly, and (c) that an increase in the concentration of potassium ions leads to a displacement of sodium ions from the substrate and accordingly to an inhibition of the reaction. If the system contains the four cations in concentrations roughly equal to those in the crab-nerve axoplasm, an increase in the sodium concentration as well as a decrease in the potassium concentration will lead to an intensification of the enzyme activity. This observation, as well as some other characteristics of the system, suggest that the adenosine triphosphatase studied here may be involved in the active extrusion of sodium from the nerve fibre.

1,697 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202229
2021970
20201,360
20191,787
20181,976
20171,921

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Topic's top 5 most impactful authors

Graham A. MacGregor

74 papers, 3.4K citations

Derek A. Denton

34 papers, 649 citations

Rolf K. H. Kinne

22 papers, 1.8K citations

Toshio Narahashi

16 papers, 1K citations

Gordon H. Williams

16 papers, 665 citations