scholarly journals Currents carried by sodium and potassium ions through the membrane of the giant axon of Loligo

1952 ◽  
Vol 116 (4) ◽  
pp. 449-472 ◽  
Author(s):  
A. L. Hodgkin ◽  
A. F. Huxley
Keyword(s):  
Giant Axon ◽  
Potassium Ions ◽  
Sodium And Potassium

scholarly journals THE EFFECT OF SODIUM AND POTASSIUM IONS ON THE IMPEDANCE CHANGE ACCOMPANYING THE SPIKE IN THE SQUID GIANT AXON

1953 ◽  
Vol 37 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Harry Grundfest ◽  
Abraham M. Shanes ◽  
Walter Freygang
Keyword(s):  
Voltage Clamp ◽  
Potassium Level ◽  
Giant Axon ◽  
Sodium Concentration ◽  
Squid Giant Axon ◽  
Potassium Ions ◽  
Impedance Change ◽  
Voltage Clamp Technique ◽  
Sodium And Potassium ◽  
Identical Fashion

Decrease of the sodium concentration of the medium depresses both the spike and the associated impedance change in almost identical fashion. Elevation of the potassium level also depresses both phenomena, but affects the impedance change more than the spike; it slows the return to the initial impedance level. The effects on the threshold to brief square waves are also described. These results appear largely accounted for by the observations of Hodgkin and Huxley with the voltage clamp technique and by their recent hypothesis as to nature of the spike processes.

scholarly journals ANESTHETIC AND CALCIUM ACTION IN THE VOLTAGE CLAMPED SQUID GIANT AXON

1959 ◽  
Vol 42 (4) ◽  
pp. 793-802 ◽  
Author(s):  
A. M. Shanes ◽  
W. H. Freygang ◽  
H. Grundfest ◽  
E. Amatniek
Keyword(s):  
Local Anesthetics ◽  
Membrane Conductance ◽  
Giant Axon ◽  
Squid Giant Axon ◽  
Potassium Ions ◽  
Outward Currents ◽  
Low Levels ◽  
Sodium And Potassium

Changes in spike configuration and in the inward and outward currents of voltage-clamped axons agree in indicating that the increases in permeability to sodium and potassium ions during activity are depressed by procaine and cocaine and augmented by calcium. At low levels of depolarization, the effect of the multivalent ion is similar to that of the local anesthetics, in keeping with their similar effects on the threshold of excitability. The reduction of membrane conductance at rest requires a higher concentration of the drugs than that needed to affect the increase in permeability with activity.

Sodium and Potassium Fluxes in the Abdominal Nerve Cord of the Cockroach, Periplaneta Americana L

1961 ◽  
Vol 38 (2) ◽  
pp. 315-322
Author(s):  
J. E. TREHERNE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Periplaneta Americana ◽  
Unit Area ◽  
Potassium Ions ◽  
Sodium Ions ◽  
Nerve Sheath ◽  
The Central Nervous System ◽  
Sodium And Potassium

1. The influx of sodium and potassium ions into the central nervous system of Periplaneta americana has been studied by measuring the increase in radioactivity within the abdominal nerve cord following the injection of 24NA and 42K. into the haemolymph. 2. The calculated influx of sodium ions was approximately 320 mM./l. of nerve cord water/hr. and of potassium ions was 312 mM./l. of nerve cord water/hr. These values are very approximately equivalent to an influx per unit area of nerve cord surface of 13.9 x 10-2 M cm. -2 sec.-1 for sodium and 13.5 x 10-12 M cm. -2 sec.-1 for potassium ions. 3. The relatively rapid influxes of these ions are discussed in relation to the postulated function of the nerve sheath as a diffusion barrier. It is suggested that a dynamic steady state rather than a static impermeability must exist across the sheath surrounding the central nervous system in this insect.

Tetanic hyperpolarization of single medullated nerve fibers in sodium and lithium

1976 ◽  
Vol 231 (4) ◽  
pp. 1033-1038 ◽  
Author(s):  
GM Schoepfle
Keyword(s):  
Steady State ◽  
Interspike Interval ◽  
Nerve Fibers ◽  
Repetitive Stimulation ◽  
Time Dependent ◽  
Potassium Ions ◽  
Current Densities ◽  
Medullated Nerve Fiber ◽  
Sodium And Potassium ◽  
Stimulation Of

Repetitive stimulation of a single medullated nerve fiber of Xenopus yields a succession of postspike voltage-time curves which are nearly coincident until attainment of a voltage that corresponds to that of the maximum attained by the normal postspike undershoot. Initially the interspike potential returns toward a resting level after this brief phase of hyperpolarization. However, as tetanization proceeds, a pattern of hyperpolarization develops with the result that, in the tetanic steady state, there exists a progressive hyperpolarization throughout each interspike interval. Extent of postspike hyperpolarization in terms of a deviation deltaVm from the resting level of membrane potential is approximated by the variation deltaVm = delta[MNa + MK]/[GNa + GK] where MNa and MK are current densities associated with active pumping of sodium and potassium ions and GNa and GK are corresponding time-dependent leak conductances. Tetanic hyperpolarization is reversibly abolished by cyanide and by exposure to lithium Ringer. Eventual reappearance of tetanic hyperpolarization in the presence of lithium Ringer suggests lithium pumping.

scholarly journals Effect of Handling on ATP Utilization of Cerebral Na,K-ATPase in rats with Trimethyltin-Induced Neurodegeneration.

2021 ◽  
Author(s):  
Barbora Kalocayova ◽  
Denisa Snurikova ◽  
Jana Vlkovicova ◽  
Veronika Navarova Stara ◽  
Dominika Michalikova ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Kinetic Properties ◽  
Potassium Ions ◽  
Catalytic Subunits ◽  
Key Enzyme ◽  
Male Wistar Rats ◽  
Frontal Cerebral Cortex ◽  
Α3 Subunit ◽  
The Brain ◽  
Sodium And Potassium

Abstract Previously it was shown that for reduction of anxiety and stress of experimental animals, preventive handling seems to be one of the most effective methods. The present study was oriented on Na,K-ATPase, a key enzyme for maintaining proper concentrations of intracellular sodium and potassium ions. Malfunction of this enzyme has an essential role in the development of neurodegenerative diseases. It is known that this enzyme requires approximately 50% of the energy available to the brain. Therefore in the present study utilization of the energy source ATP by Na,K-ATPase in the frontal cerebral cortex, using the method of enzyme kinetics was investigated. As a model of neurodegeneration treatment with Trimethyltin (TMT) was applied. Daily handling (10 min/day) of healthy rats and rats suffering neurodegeneration induced by administration of TMT in a dose of (7.5 mg/kg), at postnatal days 60-102 altered the expression of catalytic subunits of Na,K-ATPase as well as kinetic properties of this enzyme in frontal cerebral cortex of adult male Wistar rats. Everyday handling of rats, beside the previously published beneficial effect on spatial memory was accompanied by improwed maintenance of sodium homeeostasis in frontal cortex of brains. The key system responsible for this proces, the Na,K-ATPase was able to utilize better the energy substrate ATP. In rats with TMT-induced neurodegeneration handling promoted the expresion of α2 isoform of the enzyme which is typical for glial cells. In healthy rats the handling was followed by increased expression α3 subunit which is typical for neurons.

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