scholarly journals The Effect of High Sodium Concentration on the Action Potential of the Skate Heart

1967 ◽  
Vol 50 (3) ◽  
pp. 505-517 ◽  
Author(s):  
Issei Seyama ◽  
Hiroshi Irisawa
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Sea Water ◽  
Least Squares Method ◽  
Sodium Concentration ◽  
High Sodium ◽  
Low Sodium ◽  
Other Substances ◽  
Almost All ◽  
High Sodium Concentration

It already has been well documented that the maximum rate of depolarization and amplitude of action potentials are directly dependent on [Na+]o in the vertebrate myocardium. Almost all studies have been carried out at low sodium concentration ranges by substituting NaCl for other substances. Action potentials should be demonstrable in higher sodium concentrations, but cells are inevitably damaged by osmotic changes. The blood of elasmobranchs is nearly isosmotic with sea water, but NaCl accounts for 54.5% of the osmotic pressure and 38.7% of it is maintained by urea molecules. Utilizing this special situation in elasmobranchs, the effect of high sodium concentration was studied up to 170% of normal sodium concentration, while still retaining isosmotic condition. The rate of depolarization, amplitude, and duration of the myocardial action potential all increased in direct proportion to [Na+]o, and no depressant effect on transmembrane action potentials was observed in solutions of high sodium concentration. With regard to depolarization rate, the regression curve fitted by the least squares method passed through zero within two standard errors. At high sodium levels, the overshoot changed as expected theoretically, but at lower ranges it deviated from the theoretical values. [Na+]i, and [K+]i, in this tissue have been determined, and these data are explained on the basis of the Na theory.

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.

A note on the response of growing rabbits to varying levels of sodium hydroxide-treated straw

1982 ◽  
Vol 34 (1) ◽  
pp. 107-110 ◽  
Author(s):  
M. A. Lindeman ◽  
T. D. A. Brigstocke ◽  
P. N. Wilson
Keyword(s):  
Sodium Hydroxide ◽  
Response Curve ◽  
Detrimental Effect ◽  
Sodium Concentration ◽  
Dietary Sodium ◽  
Food Conversion ◽  
Depressing Effect ◽  
High Sodium ◽  
Development Unit ◽  
High Sodium Concentration

ABSTRACTTwo trials were conducted at the BOCM Silcock Development Unit at Stoke Mandeville. The first trial evaluated the response on doe and progeny, from mating to 8 weeks after parturition, of rabbit compound diets containing 0, 100, 200 and 300 g sodium hydroxide-treated straw per kg. Performance data showed no detrimental effect of inclusion levels up to 300 g sodium hydroxide-treated straw per kg despite its high sodium concentration.A second trial was made to ascertain whether these findings were due to the treated straw itself or to increasing sodium concentrations. A standard rabbit compound diet containing 2·5 g sodium per kg was compared with diets containing either 5·0 or 10·0 g sodium per kg, and with experimental compound diets containing either 80 g sodium hydroxide-treated straw or 80 g untreated straw per kg and both containing 2·5 g sodium per kg. Peak food conversion was estimated to occur at a dietary sodium concentration of 4·6g/kg, although the slope of the dose response curve was not statistically significant at the P ≤ level.The results indicate that compound diets containing up to 80 to lOOg sodium hydroxide-treated straw per kg may be fed to rabbits and that inclusion of levels of up to 300 g sodium hydroxide-treated straw per kg are not detrimental to performance. On the other hand, an inclusion of 80 g untreated ground straw per kg in compound diets for rabbits had a growth-depressing effect.

Ionic Composition of Haemolymph and Nervous Function in the Cockroach, Periplaneta Americana L

1968 ◽  
Vol 49 (1) ◽  
pp. 31-38
Author(s):  
Y. PICHON ◽  
J. BOISTEL
Keyword(s):  
Action Potentials ◽  
Periplaneta Americana ◽  
Extracellular Fluid ◽  
Sodium Concentration ◽  
Resting Potential ◽  
Equilibrium Potential ◽  
Unequal Distribution ◽  
High Sodium ◽  
Giant Axons ◽  
Nerve Cords

1. Resting and action potentials have been recorded in giant axons of the cockroach when the intact nerve cord was bathed in the insect's own haemolymph. 2. Low resting potentials (43.0±4.8 mV.) and large action potentials (105.1±6.8 mV.) were obtained in these preparations as compared with those recorded in de-sheathed nerve cords. 3. Recordings of the maximum rates of rise and fall have shown that the shape of the action potential was essentially similar in de-sheathed preparations and in intact nerve cords. 4. These results have been discussed in terms of the unequal distribution of ions between the haemolymph, the extracellular fluid and the axoplasm of the giant axons. 5. The low measured resting potential agrees with a K+ concentration in the haemolymph of about 20 mM./l., a value which is only slightly lower than the measured one (Pichon, 1963). 6.The occurrence of large action potentials in these apparently depolarized axons may be related to the stabilizing action of divalent cations such as Ca2+ which are contained in the extracellular fluid in relatively large amounts. 7. The very large recorded overshoots (62.1±7.0 mV.) may be linked with a low sodium concentration in the axoplasm and a high sodium concentration in the extracellular fluid of the giant axons of intact nerve cords, thus resulting in a high sodium equilibrium potential, ENa.

THE ELECTRICAL PROPERTIES OF THE SMOOTH MUSCLE CELL MEMBRANE

1958 ◽  
Vol 36 (9) ◽  
pp. 959-975 ◽  
Author(s):  
E. E. Daniel ◽  
H. Singh
Keyword(s):  
Smooth Muscle ◽  
Electrical Properties ◽  
Action Potential ◽  
Action Potentials ◽  
Maximum Rate ◽  
Sodium Current ◽  
Choline Chloride ◽  
Total Duration ◽  
Smooth Muscles ◽  
Sodium Concentration

In myometrium from pregnant cat, repetitive action potentials have been recorded during contraction. Using intracellular electrodes the depolarizations averaged 35 mv. Maximum rate of depolarization was 1–2 v/sec and the action potential duration varied from 250 milliseconds to much longer periods. Membrane reversal of up to 10 mv sometimes occurred. Total resistance decreased during depolarization and recovered during repolarization. Typical biphasic potentials were also recorded with extracellular electrodes. Their amplitude (peak to peak) varied from 0.3 to several millivolts and their duration (peak to peak) from 10–40 milliseconds. Reduction of external sodium concentration to as little as one-ninth normal (choline chloride or sucrose replacement) did not reduce the amplitudes of the resting or action potentials measured intracellularly or extracellularly, but decreased the action potential frequency. Membrane reversal still occurred with intracellular electrodes and the maximum rate of depolarization was unchanged. The rate of repolarization was increased so that the total duration of the action potential was 150 to 200 milliseconds. With extracellular electrodes, the peak to peak amplitudes were increased and the durations were unchanged. Further reduction of external sodium concentration to less than 15–20 meq/liter caused a contraction without further change in action potential configuration. Gradual relaxation and slowing of the repetition rate of action potentials occurred and resulted eventually in complete mechanical and electrical inactivity.Rabbit taenia coli were also studied and their electrical properties contrasted to those of cat myometrium. The conclusions were reached that: (1) the available evidence opposes the hypotheses that an inward sodium current accounts for depolarization in smooth muscle and (2) smooth muscles differed in their electrical properties and mechanisms of ion distribution not only from striate muscles but also from one another.

HIGH SODIUM CONCENTRATION MODULATES DENDRITIC CELLS IMMUNE FUNCTIONS

2018 ◽  
Vol 36 (Supplement 1) ◽  
pp. e111
Author(s):  
S. Al-Hajj ◽  
A. Goumard ◽  
A. Heraud ◽  
S. Georgeault ◽  
J. Burlaud-Gaillard ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Sodium Concentration ◽  
Immune Functions ◽  
High Sodium ◽  
High Sodium Concentration

scholarly journals Strophanthidin-Sensitive Components of Potassium and Sodium Movements in Skeletal Muscle As Influenced by the Internal Sodium Concentration

1968 ◽  
Vol 52 (3) ◽  
pp. 389-407 ◽  
Author(s):  
R. A. Sjodin ◽  
L. A. Beaugé
Keyword(s):  
Sodium Concentration ◽  
Ringer Solution ◽  
Intracellular Sodium ◽  
Sodium Ions ◽  
Potassium Efflux ◽  
Sodium Efflux ◽  
High Sodium ◽  
Ringer’S Solution ◽  
Low Sodium ◽  
Potassium Influx

"Low sodium" muscles were prepared which contained around 5 mmoles/kg fiber of intracellular sodium. "High sodium" muscles containing between 15 and 30 mmoles/kg fiber of intracellular sodium were also prepared. In low sodium muscles application of 10-5 M strophanthidin reduced potassium influx by about 5%. Potassium efflux was unaffected by strophanthidin under these conditions. In high sodium muscles, 10-5 M strophanthidin reduced potassium influx by 45% and increased potassium efflux by 70%, on the average. In low sodium muscles sodium efflux was reduced by 25% during application of 10-5 M strophanthidin while in high sodium muscles similarly treated, sodium efflux was reduced by about 60%. Low sodium muscles showed a large reduction in sodium efflux when sodium ions in the Ringer solution were replaced by lithium ions. The average reduction in sodium efflux was 4.5-fold. Of the amount of sodium efflux remaining in lithium. Ringer's solution, 40% could be inhibited by application of 10-5 M strophanthidin. The total sodium efflux from low sodium muscles exposed to Ringer's solution in which lithium had been substituted for sodium ions for a period of 1 hr can be fractionated as 78% Na-for-Na interchange, 10% strophanthidin-sensitive sodium pump, and 12% residual sodium efflux. It is concluded that large strophanthidin-sensitive components of sodium and potassium flux can be expected only at elevated sodium concentrations within the muscle cells.

Ephaptic transmission in squid giant axons

1978 ◽  
Vol 234 (5) ◽  
pp. C162-C169 ◽  
Author(s):  
F. Ramon ◽  
J. W. Moore
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Extracellular Volume ◽  
Giant Axons ◽  
Low Sodium ◽  
Ephaptic Transmission ◽  
Transmembrane Voltage ◽  
Restricted Volume ◽  
Small Voltage ◽  
Extracellular Potentials

Some characteristics of ephaptic transmission of action potentials were investigated with squid giant axons. For these studies two isolated axons were placed side by side or, on occasion, a single long axon was looped to form an "ephapse" between the axon trunk and one of its main branches. Extracellular potentials measured adjacent to axons surrounded by a very restricted volume of liquid ranged up to 80 mV in magnitude and had a shape similar to that of the membrane current. Intracellular records of the same axon regions show small voltage deflections; however, the transmembrane voltage (Vm = Vi - Vo) has the appearance of normally propagated action potentials. Ephaptic transmission of action potentials is possible when the ephaptic region is submerged in oil, as well as when the region is immersed in low-calcium solutions. When the speed of the propagated action potential is lowered by replacing the normal artifical seawater (ASW) with low-sodium ASW, some ephaptic effects are enhanced. It is concluded that in regions in which axons are confined by restricted extracellular volume, the large extracellular voltage changes arising during the passage of an action potential in one can cause ephaptic excitation in another.

THE ELECTRICAL PROPERTIES OF THE SMOOTH MUSCLE CELL MEMBRANE

1958 ◽  
Vol 36 (1) ◽  
pp. 959-975 ◽  
Author(s):  
E. E. Daniel ◽  
H. Singh
Keyword(s):  
Smooth Muscle ◽  
Electrical Properties ◽  
Action Potential ◽  
Action Potentials ◽  
Maximum Rate ◽  
Sodium Current ◽  
Choline Chloride ◽  
Total Duration ◽  
Smooth Muscles ◽  
Sodium Concentration

In myometrium from pregnant cat, repetitive action potentials have been recorded during contraction. Using intracellular electrodes the depolarizations averaged 35 mv. Maximum rate of depolarization was 1–2 v/sec and the action potential duration varied from 250 milliseconds to much longer periods. Membrane reversal of up to 10 mv sometimes occurred. Total resistance decreased during depolarization and recovered during repolarization. Typical biphasic potentials were also recorded with extracellular electrodes. Their amplitude (peak to peak) varied from 0.3 to several millivolts and their duration (peak to peak) from 10–40 milliseconds. Reduction of external sodium concentration to as little as one-ninth normal (choline chloride or sucrose replacement) did not reduce the amplitudes of the resting or action potentials measured intracellularly or extracellularly, but decreased the action potential frequency. Membrane reversal still occurred with intracellular electrodes and the maximum rate of depolarization was unchanged. The rate of repolarization was increased so that the total duration of the action potential was 150 to 200 milliseconds. With extracellular electrodes, the peak to peak amplitudes were increased and the durations were unchanged. Further reduction of external sodium concentration to less than 15–20 meq/liter caused a contraction without further change in action potential configuration. Gradual relaxation and slowing of the repetition rate of action potentials occurred and resulted eventually in complete mechanical and electrical inactivity.Rabbit taenia coli were also studied and their electrical properties contrasted to those of cat myometrium. The conclusions were reached that: (1) the available evidence opposes the hypotheses that an inward sodium current accounts for depolarization in smooth muscle and (2) smooth muscles differed in their electrical properties and mechanisms of ion distribution not only from striate muscles but also from one another.

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