Roles of External Ions in the Excitationcontractioncoupling of Frog Skeletal Muscle

Mashima, Hidenobu; Matsumura, Moto

doi:10.2170/jjphysiol.12.639

Cited by 34 publications

(17 citation statements)

References 26 publications

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“…3 practically no twitch tension could be detected at external Na+ concentrations below 40 mm, at least for the experimental conditions used here. This result is at variance with those of Overton (1902), Edwards, Ritchie & Wilkie (1956), Mashima & Matsumura (1962), Grabowski, Lobsiger & Littgau (1972), and Vaughan, Howell & Eisenberg (1972), whose experiments indicate that at [Na+]. = 40 ml the twitch tension is still practically normal.…”

Section: Methodssupporting

confidence: 62%

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Inward movement of sodium ions in resting and stimulated frog's sartorius muscle

Venosa¹

1974

The Journal of Physiology

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SUMMARY1. Paired frog sartorius muscles were exposed to Ringer solutions labelled with 22Na+ for about 20 min. At the end of this exposure one of them was stimulated supramaximally one hundred to two hundred times. Immediately after the stimulation both members of the pair were washed in a series of tubes filled with a Na+-free medium containing 3 x 10-5 M strophanthidin.2. Under the above conditions the intracellular component of the efflux was exponential with an average time constant (r) of 388 min, that is, approximately four times longer than in the presence of normal Ringer. On the other hand the mean r for the washout of the interfibre space was 3-2 min. 3. From the extrapolation to time zero of the intracellular component of the washout curve the initial intracellular radioactivity of both muscles was obtained and the resting and extra Na+ influx were calculated.4. The mean surface membrane area/muscle weight ratio was found to be 552 cm2.

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Section: Methodssupporting

confidence: 62%

“…The smaller action potentials usually seen in the presence of Na+ deficient solutions are also longer than those in the presence of normal Ringer (Nastuk & Hodgkin, 1950;Ferroni & Bianchi, 1965;Akaike & Noda, 1972 (Mashima & Matsumura, 1962).…”

Section: The Resting Na+ Influxmentioning

confidence: 89%

Inward movement of sodium ions in resting and stimulated frog's sartorius muscle

Venosa¹

1974

The Journal of Physiology

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“…Although twitch in frog's twitch muscle is scarcely inhibited by a removal of external calcium, this has been explained by the assumption that there is some calcium which might initiate contraction on or within the muscle fibres (MASHIMA and MATSUMURA, 1962). It was observed in the present work that the potassium contracture of the heart muscle of Dolabella was perfectly eliminated by a complete removal of calcium ions from the external fluid.…”

Section: Discussionmentioning

confidence: 46%

Potassium Contracture and Its Modification by Cations in the Heart Muscle of the Marine Mollusc, Dolabella Auricula

Nomura

1965

Jpn.J.Physiol

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“…Effects o f sodium removal on twitch tension MASHIMA and MATSUMURA (1962) first reported the potentiating effect of low sodium on the twitch of the skeletal muscle. This effect was maximum when sodium replacement was 50% and occurred in spite of a reduction in spike height of the action potential.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, the effect of reduction or removal of external sodium on the contractility has' not yet been analyzed in skeletal muscle, although some authors reported a potentiating effect on the twitch (MASHIMA and MATSUMURA, 1962;HATAE and KAWATA, 1984). We examined the effects of sodium removal from the viewpoint of the excitation-contraction (E-C) coupling and compared those among various types of contraction such as twitch, electrically induced contracture, potassium contracture, and caffeine contracture.…”

mentioning

confidence: 99%

Effects of External Sodium Removal on the Contracture of Frog Skeletal Muscle

Kawata

Fujishiro

1988

Jpn.J.Physiol

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Effects of removal of the external sodium on the contractility of the frog's skeletal muscle were studied. Sodium-free solution, replaced by choline, strongly augmented the twitch tension before it abolished the action potential. A similar marked potentiation was also observed in the sustained contracture induced by a small depolarization under the currentclamped condition where generation of conductive action potential was blocked. On the other hand, the maximum contracture induced either by electrical stimulation or by high potassium solution was not modified by lowering the external sodium concentration. Furthermore, contraction threshold measured on the electrically induced contracture was shifted to more negative value of the membrane potential. Caffeine contracture, examined by a short-term application of 5 mM caffeine, was first inhibited by sodium-free solution but afterwards restored or even augmented during the sodium-free perfusion. From these observations it is concluded that a removal of external sodium lowered the mechanical threshold of the muscle by affecting some step of the coupling process at the T-SR junction without affecting the contractile machinery.

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Roles of External Ions in the Excitationcontractioncoupling of Frog Skeletal Muscle

Cited by 34 publications

References 26 publications

Inward movement of sodium ions in resting and stimulated frog's sartorius muscle

Inward movement of sodium ions in resting and stimulated frog's sartorius muscle

Potassium Contracture and Its Modification by Cations in the Heart Muscle of the Marine Mollusc, Dolabella Auricula

Effects of External Sodium Removal on the Contracture of Frog Skeletal Muscle

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