scholarly journals The Dual Effect of Lithium Ions on Sodium Efflux in Skeletal Muscle

1968 ◽  
Vol 52 (3) ◽  
pp. 408-423 ◽  
Author(s):  
L. A. Beaugé ◽  
R. A. Sjodin
Keyword(s):  
Skeletal Muscle ◽  
Muscle Cells ◽  
Sodium Concentration ◽  
Ringer Solution ◽  
Sodium Content ◽  
Sartorius Muscle ◽  
Lithium Ions ◽  
Sodium Efflux ◽  
Ringer’S Solution ◽  
Equivalent Quantity

Sartorius muscle cells from the frog were stored in a K-free Ringer solution at 3°C until their average sodium contents rose to around 23 mM/kg fiber (about 40 mM/liter fiber water). Such muscles, when placed in Ringer's solution containing 60 mM LiCl and 50 mM NaCl at 20°C, extruded 9.8 mM/kg of sodium and gained an equivalent quantity of lithium in a 2 hr period. The presence of 10-5 M strophanthidin in the 60 mM LiCl/50 mM NaCl Ringer solution prevented the net extrusion of sodium from the muscles. Lithium ions were found to enter muscles with a lowered internal sodium concentration at a rate about half that for entry into sodium-enriched muscles. When sodium-enriched muscles labeled with radioactive sodium ions were transferred from Ringer's solution to a sodium-free lithium-substituted Ringer solution, an increase in the rate of tracer sodium output was observed. When the lithium-substituted Ringer solution contained 10-5 M strophanthidin, a large decrease in the rate of tracer sodium output was observed upon transferring labeled sodium-enriched muscles from Ringer's solution to the sodium-free medium. It is concluded that lithium ions have a direct stimulating action on the sodium pump in skeletal muscle cells and that a significantly large external sodium-dependent component of sodium efflux is present in muscles with an elevated sodium content. In the sodium-rich muscles, about 23% of the total sodium efflux was due to strophanthidin-insensitive Na-for-Na interchange, about 67% being due to strophanthidin-sensitive sodium pumping.

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.

Intracellular pH recovery from lactic acidosis of single skeletal muscle fibres

1988 ◽  
Vol 66 (12) ◽  
pp. 1560-1564 ◽  
Author(s):  
Y. E. Allard
Keyword(s):  
Skeletal Muscle ◽  
Lactic Acid ◽  
Intracellular Ph ◽  
Buffer Capacity ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Diffusion Limited ◽  
Skeletal Muscle Fibres ◽  
Frog Sartorius

Intracellular pH (pHi, measured with H+-selective microelectrodes, in quiescent frog sartorius muscle fibres was 7.29 ± 0.09 (n = 13). Frog muscle fibres were superfused with a modified Ringer solution containing 30 mM HEPES buffer, at extracellular pH (pHo) 7.35. Intracellular pH decreased to 6.45 ± 0.14 (n = 13) following replacement of 30 mM NaCl with sodium lactate (30 mM MES, pHo 6.20). Intracellular pH recovery, upon removal of external lactic acid, depended on the buffer concentration of the modified Ringer solution. The measured values of the pHi recovery rates was 0.06 ± 0.01 ΔpHi/min (n = 5) in 3 mM HEPES and was 0.18 ± 0.06 ΔpHi/min (n = 13) in 30 mM HEPES, pHo 7.35. The Na+–H+ exchange inhibitor amiloride (2 mM) slightly reduced pHi recovery rate. The results indicate that the net proton efflux from lactic acidotic frog skeletal muscle is mainly by lactic acid efflux and is limited by the transmembrane pH gradient which, in turn, depends on the extracellular buffer capacity in the diffusion limited space around the muscle fibres.

scholarly journals Fractionation of Sodium Efflux in Frog Sartorius Muscles by Strophanthidin and Removal of External Sodium

1970 ◽  
Vol 55 (3) ◽  
pp. 401-425 ◽  
Author(s):  
P. Horowicz ◽  
J. W. Taylor ◽  
D. M. Waggoner
Keyword(s):  
Sodium Concentration ◽  
Sartorius Muscle ◽  
Complete Replacement ◽  
Sodium Efflux ◽  
Frog Sartorius Muscle ◽  
Initial Rise ◽  
Effects Of Temperature ◽  
Free Media ◽  
Frog Sartorius ◽  
Normal Ringer

The influence of strophanthidin, ouabain, and the removal of external sodium on the sodium efflux from frog sartorius muscle was measured. In freshly dissected muscles strophanthidin and ouabain in maximally effective concentrations reduced the efflux of sodium by about 50%. Of the sodium efflux which is strophanthidin-insensitive about 75% is inhibited after complete replacement of external sodium by lithium. In the absence of strophanthidin replacement of external sodium by lithium, calcium, or magnesium produces an initial rise in the sodium efflux, followed by a fall in the efflux as the exposure of the muscles to sodium-free media is continued. When the muscles are exposed for prolonged periods in sodium-free media, the fraction of internal sodium lost per minute is higher when returned to normal Ringer fluid than it was initially. The activation of sodium efflux by external sodium after long periods in sodium-free solutions is partly strophanthidin-sensitive and partly strophanthidin-insensitive. The internal sodium concentration is an important factor in these effects. The effects of temperature on the sodium efflux were also measured. Above 7°C the Q10 of both the strophanthidin-sensitive and strophanthidin-insensitive sodium efflux is about 2.0. Below 7°C the strophanthidin-insensitive sodium efflux has a Q10 of about 7.4.

scholarly journals Rapid decrease in cellular sodium and chloride content during cold incubation of cultured liver endothelial cells and hepatocytes

1997 ◽  
Vol 322 (3) ◽  
pp. 693-699 ◽  
Author(s):  
Elke R. GIZEWSKI ◽  
Ursula RAUEN ◽  
Michael KIRSCH ◽  
Irith REUTERS ◽  
Herbert DIEDERICHS ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Rat Hepatocytes ◽  
Chloride Content ◽  
Sodium Concentration ◽  
Sodium Content ◽  
Surprising Result ◽  
Sodium Influx ◽  
Sodium Efflux ◽  
Uw Solution ◽  
Liver Endothelial Cells

Hypothermia, as used for organ preservation in transplantation medicine, is generally supposed to lead to an intracellular accumulation of sodium, and subsequently of chloride, via inhibition of the Na+/K+-ATPase. However, on studying the cellular sodium concentration of cultured liver endothelial cells using fluorescence microscopy, we found a 55% decrease in the cellular sodium concentration after 30 min of cold incubation in University of Wisconsin (UW) solution. To confirm this surprising result, we set up a capillary electrophoresis method that allowed us to determine the cellular contents of inorganic cations and of inorganic anions. Using this method we measured a decrease in the cellular sodium content from 104±11 to 55±4 nmol/mg of protein, accompanied by a decrease in the chloride content from 71±9 to 25±5 nmol/mg of protein, after 30 min of cold incubation in UW solution. When the endothelial cells were incubated in cold Krebs–Henseleit buffer or in cold cell culture medium instead of UW solution, similar early decreases in cellular sodium and chloride contents were observed, thus excluding the possibility of the decreases being dependent on the preservation solution used. Furthermore, experiments with cultured rat hepatocytes yielded a similar decrease in sodium content during initiation of cold incubation in UW solution, so the decrease does not appear to be cell-specific either. These results suggest that, contrary to current opinion, sodium efflux predominates over sodium influx during the early phase of cold incubation of cells.

The influence of "nonmyoplasmic" sodium on the measured value of the sodium efflux from barnacle muscle

1981 ◽  
Vol 59 (12) ◽  
pp. 1219-1227 ◽  
Author(s):  
M. R. Menard ◽  
J. A. M. Hinke
Keyword(s):  
Extracellular Space ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Sodium Content ◽  
Flame Photometry ◽  
Free Solution ◽  
Sodium Efflux ◽  
Barnacle Muscle ◽  
Total Sodium

In single striated muscle cells of the giant barnacle Balanus nubilus, the sodium content of the myoplasm was measured with an intracellular microelectrode, and the total sodium content of the cell was measured by flame photometry, during immersion of the cells in sodium-free solution. The sodium content of the myoplasm declined slowly but steadily from ca. 10 mmol/kg water to ca. 4 mmol/kg water during immersions lasting up to 16 h. The "nonmyoplasmic" sodium content of the cells, defined as the sodium content after subtraction of the sodium in the extracellular (sorbitol) space and in the myoplasm, declined rapidly from ca. 15 mmol/kg water to ca. 3 mmol/kg water during the first 30 min of immersion in sodium-free solution, but remained constant thereafter. The rapidly lost portion of the nonmyoplasmic sodium (ca. 12 mmol/kg water) was ascribed to the extracellular space but the location of the inexchangeable portion was not discovered. The behavior of the efflux of 22Na which was loaded into the myoplasm by microinjection was consistent with this interpretation. It was concluded that the nonmyoplasmic sodium does not have an appreciable influence on the measured value of the sodium efflux from the myoplasm of barnacle muscle cells.

Water and Sodium Turnover in Coastal and Inlnad Populations of the Ash-Grey Mouse, in Western Austrlia

1981 ◽  
Vol 29 (4) ◽  
pp. 519 ◽  
Author(s):  
KD Morris ◽  
SD Bradshaw
Keyword(s):  
Urine Osmolality ◽  
Sampling Period ◽  
Sodium Concentration ◽  
Sodium Content ◽  
Turnover Rates ◽  
Coastal Habitat ◽  
Sodium Influx ◽  
Sodium Efflux ◽  
Water Influx ◽  
Water Efflux

The water and sodium turnovers of a coastal and an inland population of P. albocinereus were studied seasonally. Although the inland habitat receives considerably less rain and sodium than the coastal habitat, water turnover rates were significantly lower only in May and sodium turnover lower only in August. Water influx rates were lowest at both locations during the summer months, positively correlated with the water content of the vegetation and positively correlated with the amount of rain received in the 30 days before each sampling period. Water efflux rates were negatively correlated with urine osmolality. Sodium influx rates were highest during the summer months and were correlated with the sodium content of the vegetation but not with the sodium deposited in the study areas. Sodium efflux rates were positively correlated with the urine sodium concentration. During the dry months, water and sodium influxes are linked; this is not apparent during the wetter months. The utilization of arthropods for food during the summer months is seen as contributing to the maintenance of water balance during a period when the vegetation is low in water. Both populations breed in late spring, with young animals growing during the summer months, and water and sodium influx rates exceed efflux rates during this period.

Ba2+ ions block K+-induced contractures by antagonizing K+-induced membrane depolarization in frog skeletal muscle fibres

1982 ◽  
Vol 60 (1) ◽  
pp. 47-51 ◽  
Author(s):  
George B. Frank ◽  
Farrokh Rohani
Keyword(s):  
Skeletal Muscle ◽  
Membrane Depolarization ◽  
Membrane Potentials ◽  
Ion Concentration ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Frog Skeletal Muscle ◽  
Induced Membrane ◽  
Ringer’S Solution ◽  
Skeletal Muscle Fibres

The effects of Ba2+ ions on twitches. K+-induced contractures, and on intracellularly recorded membrane potentials (Em) and depolarizations of frog skeletal muscle fibres were investigated. Exposure of toe muscles to choline–Ringer's solution with 10−3 M Ba2+ with Ca2+ (1.08 mM) eliminated or very greatly reduced contractures produced by 60 mM K+. In contrast, not only did the same concentration of Ba2+ ions fail to depress the twitch tension of isolated semitendinosus fibres when added to Ringer's with Ca2+, but it even restored twitches that had been eliminated in a zero Ca2+ Ringer's solution. The resting Em of sartorius muscle fibres in choline–Ringer's solution was reduced about 20 mV by 10−3 M Ba2+. This Ba2+ ion concentration also antagonized the K+-induced depolarization. Thus in the presence of 1 mM Ba2+, 20 mM K+ hyperpolarized rather than depolarized the fibres and 60 or 123 mM K+ produced only very slowly developing, small depolarizations. These results suggest that the loss of the K+-induced contracture in choline–Ringer's caused by Ba2+ ions is due to an inhibition of the K+-induced depolarization. The latter result is consistent with previous findings of other workers that Ba2+ ions block membrane K+ channels.not available

Observations on the Measurement and Regulation of the Sodium Content of Human Erythrocytes

1972 ◽  
Vol 42 (4) ◽  
pp. 447-453 ◽  
Author(s):  
E. K. M. Smith
Keyword(s):  
Linear Correlation ◽  
Sodium Pump ◽  
Potassium Concentration ◽  
Normal Subjects ◽  
Sodium Concentration ◽  
Sodium Content ◽  
Active Sodium ◽  
Sodium Efflux ◽  
Precise Control ◽  
A Cell

1. The sodium concentration within the erythrocytes of 159 subjects was found to be 7·35 ± 1·25 (SD) mmol/litre of cells. 2. In 157 normal subjects, the erythrocyte potassium concentration was 99·08 ± 5·3 (SD) mmol/litre of cells. 3. In the erythrocytes from twenty-seven normal subjects there was a striking linear correlation between the rate constant for active sodium efflux and resting sodium concentration. 4. It is concluded that these studies confirm the assumption that the resting concentration of sodium within a cell is determined by the activity of the sodium pump. What is not known is the mechanism by which this precise control is maintained.

Extracts of Hymenocardia acida ameliorate insulin resistance in skeletal muscle cells

Planta Medica ◽  
2016 ◽  
Vol 81 (S 01) ◽  
pp. S1-S381
Author(s):  
II Ezeigbo ◽  
C Wheeler-Jones ◽  
S Gibbons ◽  
ME Cleasby
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Ameliorate Insulin Resistance
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