Effect of the anode and cathode of a direct current on the electrical activity of the isolated node of Ranvier in a medium with low sodium concentration and during the action of Novocain

1964 ◽  
Vol 57 (5) ◽  
pp. 523-526
Author(s):  
V. I. Belyaev
Keyword(s):  
Electrical Activity ◽  
Direct Current ◽  
Node Of Ranvier ◽  
Sodium Concentration ◽  
Low Sodium ◽  
Isolated Node

scholarly journals Sodium Radiofrequency Coils for Magnetic Resonance: From Design to Applications

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1788
Author(s):  
Giulio Giovannetti ◽  
Alessandra Flori ◽  
Nicola Martini ◽  
Roberto Francischello ◽  
Giovanni Donato Aquaro ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Sodium Concentration ◽  
Resonance Spectroscopy ◽  
Sodium Mri ◽  
Human Organs ◽  
Low Sodium ◽  
Radiofrequency Coils ◽  
Anatomical Imaging ◽  
Strong Gradient

Sodium (23Na) is the most abundant cation present in the human body and is involved in a large number of vital body functions. In the last few years, the interest in Sodium Magnetic Resonance Imaging (23Na MRI) has considerably increased for its relevance in physiological and physiopathological aspects. Indeed, sodium MRI offers the possibility to extend the anatomical imaging information by providing additional and complementary information on physiology and cellular metabolism with the heteronuclear Magnetic Resonance Spectroscopy (MRS). Constraints are the rapidly decaying of sodium signal, the sensitivity lack due to the low sodium concentration versus 1H-MRI induce scan times not clinically acceptable and it also constitutes a challenge for sodium MRI. With the available magnetic fields for clinical MRI scanners (1.5 T, 3 T, 7 T), and the hardware capabilities such as strong gradient strengths with high slew rates and new dedicated radiofrequency (RF) sodium coils, it is possible to reach reasonable measurement times (~10–15 min) with a resolution of a few millimeters, where it has already been applied in vivo in many human organs such as the brain, cartilage, kidneys, heart, as well as in muscle and the breast. In this work, we review the different geometries and setup of sodium coils described in the available literature for different in vivo applications in human organs with clinical MR scanners, by providing details of the design, modeling and construction of the coils.

scholarly journals Maximum Rate of Depolarization of Single Muscle Fiber in Normal and Low Sodium Solutions

1965 ◽  
Vol 49 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Arnaldo Ferroni ◽  
Donatella Blanchi
Keyword(s):  
Action Potentials ◽  
Maximum Rate ◽  
Sodium Current ◽  
Sodium Concentration ◽  
Single Muscle ◽  
Membrane Action ◽  
Independence Principle ◽  
Low Sodium ◽  
Intracellular Microelectrodes ◽  
Normal Tyrode Solution

The values of membrane action potentials and maximum depolarization rates of single muscle fibers in normal Tyrode solution and in low sodium solutions containing as little as 20 per cent of the sodium chloride were measured with intracellular microelectrodes. Under these conditions the membrane potential remains unchanged up to 36 per cent of [Na+]out concentration, whereas the overshoot of the action potential varies linearly with the logarithm of the external sodium concentration. The maximum depolarization rate is a linear function of the external sodium concentration. The results obtained support the ionic theory for sodium and the independence principle for sodium current related to the external sodium concentration.

scholarly journals The Ionic Basis of Electrical Activity in Embryonic Cardiac Muscle

1968 ◽  
Vol 52 (3) ◽  
pp. 666-681 ◽  
Author(s):  
Billy K. Yeh ◽  
Brian F. Hoffman
Keyword(s):  
Electrical Activity ◽  
Sodium Concentration ◽  
Cardiac Cells ◽  
Resting Potential ◽  
Extracellular Potassium ◽  
Embryonic Chick ◽  
Extracellular Potassium Concentration ◽  
Chick Heart ◽  
Extracellular Sodium ◽  
Ionic Basis

The intracellular sodium concentration reported for young, embryonic chick hearts is extremely high and decreases progressively throughout the embryonic period, reaching a value of 43 mM immediately before hatching. This observation suggested that the ionic basis for excitation in embryonic chick heart may differ from that responsible for electrical activity of the adult organ. This hypothesis was tested by recording transmembrane resting and action potentials on hearts isolated from 6-day and 19-day chick embryos and varying the extracellular sodium and potassium concentrations. The results show that for both young and old embryonic cardiac cells the resting potential depends primarily on the extracellular potassium concentration and the amplitude and rate of rise of the action potential depend primarily on the extracellular sodium concentration.

Low Na+ effects on PAH transport and permeabilities in isolated snake renal tubules

1976 ◽  
Vol 230 (2) ◽  
pp. 256-262 ◽  
Author(s):  
WH Dantzler ◽  
SK Bentley
Keyword(s):  
Concentration Gradient ◽  
Sodium Concentration ◽  
Renal Tubules ◽  
Control Medium ◽  
Free Medium ◽  
Cell Water ◽  
Apparent Permeability ◽  
Low Sodium ◽  
Significant Depression ◽  
And Control

Effects of low sodium concentrations on p-aminohippurate (PAH) transport by isolated, perfused snake (Thamnophis spp.) distal-proximal renal tubules were studied. Replacement of sodium in bath with choline led to significant depression of net PAH transport from bath to lumen in less than 10 min and to maximum depression (to 25-30% of control) in about 30 min, but transport still occurred against concentration gradient. In absence of sodium, PAH concentration in cell water was markedly depressed, but was still slightly greater than that in bath or lumen. Apparent permeability of peritubular membrane, determined from PAH efflux from tubules with oil-filled lumens, averaged about 0.5 X 10(-5) cm s-1 in 150 mM sodium and about 1.1 X 10(-5) cm s-1 in sodium-free medium. Data suggest that both decreased rate of active transport and increased apparent permeability of peritubular membrane contribute to depression of net transepithelial PAH transport and cell water PAH concentration in sodium-free medium. When sodium was restored to bath, net PAH transport nearly tripled in 15 min. Reduction of bath sodium concentration to one-half control or perfusion with sodium-free medium in lumen and control medium in bath had no effect on net PAH transport.

Luminal influences on potassium secretion: low sodium concentration

1984 ◽  
Vol 246 (5) ◽  
pp. F609-F619 ◽  
Author(s):  
D. W. Good ◽  
H. Velazquez ◽  
F. S. Wright
Keyword(s):  
Driving Forces ◽  
Sodium Concentration ◽  
Perfusion Fluid ◽  
Low Sodium ◽  
K Secretion ◽  
Potassium Secretion ◽  
Transepithelial Voltage ◽  
Series Of Experiments ◽  
Distal Tubules

In vivo microperfusion techniques were employed in anesthetized rats to determine whether K secretion by renal distal tubules requires the presence of Na in luminal fluid, and, if it does, in what concentration range do changes in Na concentration have the most effect. In a first series of experiments Na in perfusion fluid was replaced at constant Cl with tetramethylammonium (TMA). When the perfusion fluid Na concentration was reduced from 96 or 34 mM to 10 or 3 mM, K secretion was reduced by 50-60% and transepithelial voltage ( VTE ) was reduced by 40-60%. In a second series of experiments, in which NaCl was replaced with urea, perfusion fluid Na concentration again was reduced to 3 mM, and K secretion and VTE were reduced. In a third series of experiments, Na was replaced with rubidium. The reduced K secretion could not be explained solely by changes in electrical driving forces. The results indicate that some luminal Na (half-maximal concentration approx 10 mM) is necessary to permit K secretion to proceed at a normal rate. Considering prior measurements of luminal Na concentration in rat distal tubules, it is unlikely that changes in luminal Na concentration play an important role in regulating the rate of distal K secretion.

Transcranial direct current stimulation improves tinnitus perception and modulates cortical electrical activity in patients with tinnitus: A randomized clinical trial

2020 ◽  
Vol 50 (4) ◽  
pp. 289-300 ◽  
Author(s):  
Dayse da Silva Souza ◽  
Alexandre Alex Almeida ◽  
Suellen Marinho dos Santos Andrade ◽  
Daniel Gomes da Silva Machado ◽  
Márcio Leitão ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Electrical Activity ◽  
Randomized Clinical Trial ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Direct Current Stimulation ◽  
Cortical Electrical Activity

Effect of Low Electrolyte Feeding on Development of Potassium Deficiency

1957 ◽  
Vol 191 (3) ◽  
pp. 610-614 ◽  
Author(s):  
Malcolm A. Holliday ◽  
William E. Segar
Keyword(s):  
Potassium Concentration ◽  
Sodium Intake ◽  
Extracellular Volume ◽  
Sodium Concentration ◽  
Potassium Deficiency ◽  
Electrolyte Composition ◽  
Urine Excretion ◽  
Deficient Diet ◽  
Sodium Potassium ◽  
Low Sodium

Rats fed a diet deficient in sodium, potassium and chloride were observed for 3, 6, 12, 28, 60 and 110 days. Urine excretion of these ions was observed during the initial adjustment to the diet. Serum and muscle electrolyte composition was determined at the end of each interval. Initially the loss of sodium and chloride constituted a loss of extracellular volume without change in concentration. The loss of potassium in this period resulted in a decrease in the intracellular concentration of potassium. Subsequent conservation of all three substances was very effective. No alkalosis developed during the first 28 days on the deficient diet despite an 18% reduction in muscle potassium concentration. A minimal increase in muscle sodium concentration was observed at this level of potassium deficiency. Evidence indicates that this minimal increase was not a function of the low sodium intake per se but rather was characteristic of the magnitude of potassium deficiency, since a similar minimal increase in muscle sodium occurs when an adequate sodium intake is provided.

Changes of ERG due to High and Low Sodium Concentration in the Perfusing Blood of the Isolated Eye

1977 ◽  
pp. 329-333
Author(s):  
Y. Tazawa ◽  
H. Mera ◽  
H. Imaizumi ◽  
H. Kurihara ◽  
K. Imaizumi
Keyword(s):  
Sodium Concentration ◽  
Low Sodium
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