�ber die Zustands�nderungen des contractilen Systems in Abh�ngigkeit vom extracellul�ren Kalium und Natrium

Fleckenstein, A.; Hertel, Hermann

doi:10.1007/bf00369960

Cited by 54 publications

(4 citation statements)

References 22 publications

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“…The shift in threshold was first described by Fleckenstein & Hertel (1948) in whole gastrocnemius and rectus muscles. The threshold in normal [Ca]o of 20 mM-K rose to 50 mM-K after having increased [Ca]o from 1-8 to 53 mm.…”

Section: Resultsmentioning

confidence: 96%

“…A few experiments were carried out on single slow fibres from the tonus bundle of the iliofibularis (Sommerkamp, 1928;Kuffler & Vaughan Williams, 1953 (Fleckenstein & Hertel, 1948;Schaechtelin, 1961). The contractures of slow fibres differ from those of twitch fibres in several respects (see Schaechtelin, 1961, for corresponding results regarding the rectus abdominis):…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 96%

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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“…Thus Ca and Na ions may only slowly penetrate into, and escape from, these structures in skeletal muscle. A suggestion that the Ca-Na antagonism may, indeed, exist in skeletal muscle (at least in the slow fibres of the frog) can be found in experiments on the rectus abdominus muscle which showed that Ca determines the tension of KCI contractures (Denton, 1948) and that Na has to be present in order to obtain relaxation (Fleckenstein & Hertel, 1948). SUMMARY 1.…”

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confidence: 99%

The antagonism between Ca and Na ions on the frog's heart

Lüttgau¹,

Niedergerke²

1958

The Journal of Physiology

450

154

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“…It is probable that the explanation for the changes in the mechanical threshold by low ionic strength given above applies also to the contractures induced by nonionic solutions in frog tonic muscles (Fenn, 1931;Fleckenstein and Hertel, 1947;Vanremoortere, 1948;Kiessling, 1960;Schaechtelin, 1961;Van der Kloot and Rubin, 1962;LorkoviV, 1963;Irwin and Hein, 1964) and in the frog heart (Van der Kloot and Rubin, 1962). Preliminary results indicated that about the same amount of change in the mechanical threshold when the ionic strength is lowered occurs also in mammalian muscle.…”

Section: Discussionmentioning

confidence: 90%

The Influence of Ionic Strength on Potassium Contractures and Calcium Movements in Frog Muscle

Lorković

1967

The Journal of General Physiology

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ABST R ACT Frog toe muscles were bathed in isotonic, sodium-free Tris chloride, methanesulfonate, or sulfate solutions containing sucrose or mannitol and varying in ionic strength from 0.006 to 0.291. By decreasing the ionic strength the curve relating the peak tension of the K contractures to the log [K] was reversibly shifted to lower [K]. Increasing the [Ca] from 1 to 4 mM almost abolished this effect. The resting uptake of 4Ca was increased more than two times by decreasing the ionic strength from 0.125 to 0.039. It was not increased significantly by raising [Ca] from 1 to 4 mM at low or normal ionic strength. The additional uptake of 4Ca during contractures provoked by 120 m K was not significantly different at the two levels of ionic strength. The rate of emergence of 45Ca from muscles loaded with 46Ca at reduced ionic strength, was decreased. The effects of low ionic strength are discussed in terms of changes in the potential difference across a membrane with fixed negative charges on the outer surface. The Influence of Ionic Strength on Potassium Contractures and Calcium Movements in Frog MuscleIn the course of studying the effect of changes in extracellular pH on the threshold concentration of potassium necessary to produce contractures in a frog toe muscle, the responses of the muscle were found to be dependent on the composition of the solutions used. When the threshold at pH 7 and 9 was measured with solutions consisting mainly of choline chloride and having the same ionic strength at both pH levels (about 0.125), the threshold was not decreased in the alkaline solution (Lorkovi, 1967). However, if Tris-methanesulfonate solutions were used, so that the ionic strength at pH 9 was about one-third that at pH 7, the threshold concentration of potassium was lower at pH 9. To examine this, the effect on the K contracture threshold of variations in ionic strength from 0.006 to 0.291, at constant pH, was investigated. The results showed that the threshold concentration of potassium is reduced 883

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�ber die Zustands�nderungen des contractilen Systems in Abh�ngigkeit vom extracellul�ren Kalium und Natrium

Cited by 54 publications

References 22 publications

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

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

The antagonism between Ca and Na ions on the frog's heart

The Influence of Ionic Strength on Potassium Contractures and Calcium Movements in Frog Muscle

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