Effects of changes in extracellular calcium concentration on the potassium‐induced contracture of frog's skeletal muscle

Frank, George B.

doi:10.1113/jphysiol.1960.sp006457

Cited by 151 publications

(122 citation statements)

References 29 publications

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“…CAPUTO and GIMENEZ (1967) noticed the potentiating effect as the short term effect of the Ca2+ reduction. With respect to this, the inhibitory effect of Ca2+ reduction previously reported by FRANK (1960) and by KOSAKA et al (1977) and the effect observed in the present paper may be regarded as the long term effect of Ca2+ reduction.…”

Section: Resultsmentioning

confidence: 77%

Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

Tsutsuura¹,

Takauji²,

Nagai³

1984

Jpn.J.Physiol

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The effects of external Ca2+ reduction on the biphasic potassium (K) contractures and the action of divalent cations under conditions of the Ca2+ reduction were examined in detail, using frog single twitch muscle fibers. The peak tension of the initial component of 80 mM K+ contractures was greatly potentiated by exposing the fiber to low Ca2+ solution for 30 sec, and the degree of this potentiation was decreased with increasing the exposing time. In contrast, the peak tension of the secondary component was rapidly inhibited by Ca2+ reduction. The potentiation of the initial component was removed by 3 mM Mg2+ or 0.5 mM Ni2+. The inhibition of the secondary component, especially the shortening of its time course, was reversed partially by 3 mM Mg2 + and almost completely by 0.5 mM Ni2 + . The difference between the inhibitory effect of 10 mM Mg2+ or 1-3 mM Ni2+ on the initial component and that on the secondary component was also demonstrated. The tension development of the secondary component was completely inhibited by external Ca2+ reduction for 20 min, but it was observed in the presence of 3 mM Mg2+, although its time course was shorter. These results indicate that the actions of Mg2+ and Ni2+ on the initial component differ from those on the secondary component and suggest the possible mechanisms of the actions of these divalent cations on the biphasic K contractures.Key Words: frog single twitch muscle fiber, biphasic K contractures, external Ca2+ reduction, direct effect of Cat +, Mg2+ and Ni2+ effects. LUTTGAU and SPIECKER (1979) have recently reported that by external Ca2+ reduction in the presence of Mg2+, the peak tension of the maximum contractures is slightly affected, while the time course of the contractures is shortened. STEFANI (1981, 1982) reported that under the same conditions the peak con-

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Section: Resultsmentioning

confidence: 77%

Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

Tsutsuura¹,

Takauji²,

Nagai³

1984

Jpn.J.Physiol

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“…However, since only rather small amounts of Ca are required to preserve contractility, it is to be expected that Ca ions escaping from the fibre, and traces of this ion in the surrounding solution, may considerably influence the time during which contraction is not entirely abolished. This may explain the accelerating effect of EDTA (although the possibility that EDTA has additional effects in the membrane has to be considered, too), and, since in the present experiments no special precautions were taken to obtain really Ca-free fluids, it may have been the more drastically reduced extracellular Ca which caused the rather quick disappearance of contractility found by Frank (1960) in whole muscles of the frog's toe.…”

Section: Resultsmentioning

confidence: 84%

“…Contractures were induced by replacing the equilibrating solution with a sodium-free, potassium-rich solution (solution E, having 190 mM-K and unchanged Ca concentration). With 1-8 mM-Ca this contracture solution produces a rapid increase in tension, a plateau of several seconds, and a quick relaxation (Hodgkin & Horowicz, 1960a; for relevant work, concerning the effect of Ca on the time course of contractures in whole muscles, see Frank, 1960, andPauschinger &Brecht, 1961). Figure 1 shows the effect of varying [Ca]O.…”

Section: Resultsmentioning

confidence: 99%

The action of calcium ions on potassium contractures of single muscle fibres

Lüttgau¹

1963

The Journal of Physiology

208

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Calcium ions are considered to be necessary in reactions linking the electrical and mechanical events in muscle fibres (reviewed by Sandow, 1952). But, whereas the effect of calcium ions on excitable membranes (reviewed by Shanes, 1958) and muscle 'models' (reviewed by Hasselbach, 1962) have been fully investigated during the last ten years, less is known about how external calcium influences the process which controls the development of tension in skeletal muscle fibres. This paper aims at giving some information about the properties of this system, which is regarded as the first of several links coupling excitation and contraction. Single fibres were used to achieve a quick change of the external ion concentrations, since a delay would have impeded the analysis of the time course of the transient contractures in twitch fibres.A preliminary account of this work already has appeared (Liittgau, 1962). METHODSSingle fibres were isolated from the semitendinosus or iliofibularis muscles of Rana temporaria. After the dissection each fibre was left for about 1 hr in Ringer's solution and tested for excitability before being transferred from the dissection dish to the experimental cell. This transfer took place on a small glass plate, and movement of the fibre through an air-water interface was carefully avoided.Most of the experiments were carried out with the Perspex cell described by Hodgkin & Horowicz (1959). In early experiments a similar cell with a two-channel tap for changing the solutions was used. One tendon of the fibre was gripped in a Perspex clamp and the other was connected to a mechano-electrical transducer (RCA 5734) by a silver wire of 50 IL diameter. The fibre was stretched to 1-25 times slack length. A sarcomere distance of about 2-8!e was measured on some fibres under this condition. This was made at the end of the experimental procedure with a microscope fitted with a water-immersion objective.The lengths of the fibres varied from 1.0 to 2-5 cm and the diameter (stretched) from 50 to 130 ,.The flow rate was adjusted so that all the fluid in the cell was replaced at least every half second. Membrane potentials were measured with intracellular micro-electrodes of the Ling-Gerard type.Solution&. (Table 1) The fibres were dissected in a phosphate-buffered Ringer's solution (Adrian, 1956). During the experiments solutions containing 4 mM bicarbonate gassed

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“…The reduction of external Ca to 10 -9M reduced the amplitude and time course of potassium contractures, while the addition of cobalt reduced the amplitude but prolonged the time course of contractures. Previous workers have found that the amplitude and time course of potassium contractures in single fibre and whole muscle preparations are reduced and the contracture threshold increased by the reduction of Ca to 10-6M (Frank, 1960;Luttgau, 1963) or 10 9M (Frank, 1980). The amplitude of the potassium contracture was found to be unaffected if an appropriate concentration of magnesium or other divalent cation was added to Ca deficient media (Frank, 1962;Luttgau & Oetliker, 1968).…”

Section: Discussionmentioning

confidence: 98%

Potassium contractures and mechanical activation in rat skeletal muscle: effects of multivalent cations, temperature and tetracaine

Anwyl

Bruton

McLoughlin

1984

British J Pharmacology

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Effects of changes in extracellular calcium concentration on the potassium‐induced contracture of frog's skeletal muscle

Cited by 151 publications

References 29 publications

Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

The action of calcium ions on potassium contractures of single muscle fibres

Potassium contractures and mechanical activation in rat skeletal muscle: effects of multivalent cations, temperature and tetracaine

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