scholarly journals The Movement of Thallium Ions in Muscle

1960 ◽  
Vol 43 (4) ◽  
pp. 759-773 ◽  
Author(s):  
L. J. Mullins ◽  
R. D. Moore
Keyword(s):  
Ringer Solution ◽  
Sartorius Muscle ◽  
Muscle Twitch ◽  
External Concentration ◽  
Irreversible Damage ◽  
Toxic Heavy Metal ◽  
Tenfold Increase ◽  
Internal Concentration ◽  
High Concentrations ◽  
Frog Sartorius

Measurements have been made of the fluxes of thallous ions (Tl+) across the membrane of frog sartorius muscle fibers. These show that at an external concentration of 74 µM the influx is about 270 x 10-15 moles/cm.2 sec., while the efflux from a muscle with an internal concentration equal to the above is 5 x 10-15 moles/cm.2 sec. The efflux is increased of the order of 300-fold during a muscle twitch, and Tl+ reach a steady-state distribution between fiber water and Ringer solution that is very close to the corresponding ratio for K+. High concentrations of Tl+ depolarize the membrane about 58 mv. for a tenfold increase in external concentration. The results obtained are consistent with the view that the muscle fiber membrane cannot distinguish between the toxic heavy metal Tl+ and K+, provided that the concentrations of the former ion are kept low. High concentrations of Tl+, if allowed to act for an appreciable period of time, lead to irreversible damage to muscle.

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 Electrical Properties and Excitation-Contraction Coupling in Skeletal Muscle Treated with Ethylene Glycol

1972 ◽  
Vol 60 (2) ◽  
pp. 221-236 ◽  
Author(s):  
Carlos Sevcik ◽  
Toshio Narahashi
Keyword(s):  
Membrane Potential ◽  
Ethylene Glycol ◽  
Control Level ◽  
Membrane Resistance ◽  
Ringer Solution ◽  
Resting Membrane Potential ◽  
Sartorius Muscle ◽  
Frog Sartorius ◽  
Specific Membrane ◽  
Normal Ringer

The contractility of the frog sartorius muscle was suppressed after treatment with a Ringer solution added with ethylene glycol (EGR). No contraction was elicited by nerve stimulation when the muscle was brought back to normal Ringer solution after having been soaked in 876 mM EGR for 4 hr or in 1095 mM EGR for 2 hr. However, the action potential of normal amplitude was generated and followed by a depolarizing afterpotential. The resting membrane potential was slightly decreased from the mean normal value of –91.1 mv to –78.8 mv when 1095 mM EGR was used, and to –82.3 mv when 876 mM EGR was used, but remained almost constant for as long as 2 hr. The afterpotential that follows a train of impulses and a slow change in membrane potential produced by a step hyperpolarizing current (so-called "creep") were suppressed after treatment with ethylene glycol. The specific membrane capacity decreased to about 50% of the control values while the specific membrane resistance increased to about twice the control values Therefore, the membrane time constant remained essentially unchanged. The water content of the muscle decreased by about 30% during a 2 hr immersion in 1095 mM EGR, and increased by about 30% beyond the original control level after bringing the muscle back to normal Ringer. The intracellular potassium content did not change significantly during these procedures. Some differences between the present results and those obtained with glycerol are discussed.

scholarly journals SELECTIVE DISRUPTION OF THE SARCOTUBULAR SYSTEM IN FROG SARTORIUS MUSCLE

1968 ◽  
Vol 39 (2) ◽  
pp. 451-467 ◽  
Author(s):  
Brenda Eisenberg ◽  
Robert S. Eisenberg
Keyword(s):  
Extracellular Space ◽  
Skeletal Muscles ◽  
Muscle Fibers ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Normal Muscle ◽  
Tubular System ◽  
Sarcotubular System ◽  
Reliable Marker ◽  
Frog Sartorius

Skeletal muscles which have been soaked for 1 hr in a glycerol-Ringer solution and then returned to normal Ringer solution have a disrupted sarcotubular system. The effect is associated with the return to Ringer's since muscles have normal fine structure while still in glycerol-Ringer's. Karnovsky's peroxidase method was found to be a very reliable marker of extracellular space, filling 98.5% of the tubules in normal muscle. It was interesting to note that only 84.1% of the sarcomeres in normal muscle have transverse tubules. The sarcotubular system was essentially absent from glycerol-treated muscle fibers, only 2 % of the tubular system remaining connected to the extracellular space; the intact remnants were stumps extending only a few micra into the fiber. Thus, glycerol-treated muscle fibers provide a preparation of skeletal muscle with little sarcotubular system. Since the sarcoplasmic reticulum is not destroyed and the sarcolemma and myofilaments are intact in this preparation, of the properties of the sarcolemma may thus be separated from those of the tubular system.

scholarly journals A Study on the Electrical Resistance of the Frog Sartorius Muscle

1966 ◽  
Vol 49 (5) ◽  
pp. 897-912 ◽  
Author(s):  
Otto Schanne ◽  
Hiroshi Kawata ◽  
Bärbel Schäfer ◽  
Marc Lavallée
Keyword(s):  
Muscle Fiber ◽  
Potassium Concentration ◽  
Membrane Resistance ◽  
Ringer Solution ◽  
Effective Resistance ◽  
Sartorius Muscle ◽  
Cable Model ◽  
Frog Sartorius Muscle ◽  
Electrode Resistance ◽  
Frog Sartorius

Four different methods of measuring the resistance of a muscle fiber have been applied to the frog sartorius muscle. The methods, in which the resistance of the microelectrode entered the calculation of the effective resistance of the fiber, resulted in values which were 8 times higher than the resistance values obtained with methods independent of the electrode resistance. A simple cable model of a muscle fiber could not account for the discrepancy in the effective resistance found in these measurements; therefore, an enlarged cable model for a muscle fiber has been proposed, and its biological implications have been discussed. The effective resistance (measured with the two different groups of methods) decreased when the potassium concentration in the bath increased. Using the proposed enlarged cable model for the interpretation of these results, it is shown that not only the membrane resistance but also the myoplasmic resistance decreases with an increasing potassium concentration in the Ringer solution.

Effect of pH on muscle fatigue in isolated frog sartorius muscle

1980 ◽  
Vol 58 (5) ◽  
pp. 568-570 ◽  
Author(s):  
E. Don Stevens
Keyword(s):  
Muscle Fatigue ◽  
Phosphate Buffer ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Effect Of Ph ◽  
Frog Sartorius Muscle ◽  
Frog Sartorius

Isolated frog sartorius muscle was incubated for 3 h in Ringer solution (5 mM phosphate buffer) at pH 7 or pH 8. Each muscle was stimulated supramaximally at 2 per second continuously. Muscles at pH 7 fatigued more quickly than those at pH 8. Muscles at pH 8 released acid whereas those at pH 7 did not.

scholarly journals A new method for excitation-contraction uncoupling in frog skeletal muscle.

1978 ◽  
Vol 78 (3) ◽  
pp. 782-784 ◽  
Author(s):  
J del Castillo ◽  
G Escalona de Motta
Keyword(s):  
Electrical Activity ◽  
Prolonged Exposure ◽  
Neuromuscular Block ◽  
Ringer Solution ◽  
Mechanical Activity ◽  
Sartorius Muscle ◽  
Nerve Branch ◽  
Miniature Endplate Potentials ◽  
Endplate Potentials ◽  
Frog Sartorius

The mechanical activity of frog sartorius muscle fibers can be uncoupled from the electrical activity of their surface membranes by immersing the preparation in Ringer solution containing either 1.5 or 2.0 M of formamide for 15--20 min. This uncoupling is not reversed when the muscle is transferred to normal frog Ringer solution. Formamide does not affect the electrical activity of the sciatic nerve branch, and both endplate potentials and miniature endplate potentials may be recorded from the uncoupled muscles. Prolonged exposure to formamide, beyond the time needed to paralyze, causes neuromuscular block.

Prepotentials and unidirectional propagation in myocardium

1961 ◽  
Vol 201 (5) ◽  
pp. 873-880 ◽  
Author(s):  
T. Hoshiko ◽  
Nick Sperelakis
Keyword(s):  
Current Flow ◽  
Reverse Direction ◽  
Sartorius Muscle ◽  
Potential Response ◽  
Ringer’S Solution ◽  
Current Pulses ◽  
Negative Current ◽  
Reversed Polarity ◽  
Bidirectional Propagation ◽  
Frog Sartorius

In frog ventricular strips bathed in Ca-free Ringer's solution containing 6–30 mm/liter Mg and treated with conditioning current pulses, propagation became impaired. An exaggerated foot, or prepotential, was consistently more prominent when the conditioned strip was stimulated from one end than from the other. Occasionally a prepotential in isolation alternated with a prepotential plus action potential response. After further treatment with current pulses, propagation failed in the direction of negative current flow. Thresholds of impaled cells were identical. Bidirectional propagation was restored in Ringer's solution. Conditioning pulses of reversed polarity induced unidirectional propagation in the reverse direction. Propagation in frog sartorius muscle was not blocked under similar conditions. Prepotentials and unidirectional propagation may be explained by junctional transmission from cell to cell.

scholarly journals Changes in the Membrane Permeability of Frog's Sartorius Muscle Fibers in Ca-Free EDTA Solution

1963 ◽  
Vol 47 (2) ◽  
pp. 379-392 ◽  
Author(s):  
H. Kimizuka ◽  
K. Koketsu
Keyword(s):  
Membrane Permeability ◽  
Chloride Content ◽  
Chloride Ions ◽  
Sartorius Muscle ◽  
Constant Field ◽  
Sodium Influx ◽  
Sodium Potassium ◽  
Edta Solution ◽  
Frog Sartorius ◽  
Sodium And Potassium

The changes in the membrane permeability to sodium, potassium, and chloride ions as well as the changes in the intracellular concentration of these ions were studied on frog sartorius muscles in Ca-free EDTA solution. It was found that the rate constants for potassium and chloride efflux became almost constant within 10 minutes in the absence of external calcium ions, that for potassium increasing to 1.5 to 2 times normal and that for chloride decreasing about one-half. The sodium influx in Ca-free EDTA solution, between 30 and 40 minutes, was about 4 times that in Ringer's solution. The intracellular sodium and potassium contents did not change appreciably but the intracellular chloride content had increased to about 4 times normal after 40 minutes. By applying the constant field theory to these results, it was concluded that (a) PCl did not change appreciably whereas PK decreased to a level that, in the interval between 10 and 40 minutes, was about one-half normal, (b) PNa increased until between 30 and 40 minutes it was about 8 times normal. The low value of the membrane potential between 30 and 40 minutes was explained in terms of the changes in the membrane permeability and the intracellular ion concentrations. The mechanism for membrane depolarization in this solution was briefly discussed.

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