The role of calcium and zinc in the electrical and mechanical responses of frog sartorius muscle

Edman, K. A. P.; Grieve, D. W.

doi:10.1007/bf02156422

Cited by 23 publications

(16 citation statements)

References 9 publications

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“…The results are in agreement with Ca and Mg experiments on superficial fibres in whole muscles by Edman & Grieve (1961) and Jenden & Reger (1962 Hodgkin & Horowicz (1960a) found an S-shaped relation between the logarithm of the external potassium concentration in which the fibres recovered after a contracture in 190 mM-K, and the state of the contractile system, tested by a second increase in [K]O. In this section the effect of [Ca]o on this relation, i.e.…”

Section: Resultssupporting

confidence: 91%

“…Theoretically, an inactivation of the contractile system at a normal resting potential is possible. However, such a situation was never observed in experiments in which the resting potential was measured with internal electrodes (Edman & Grieve, 1961;Jenden & Reger, 1962;this paper, p. 685 Mg ions can replace Ca, at least for the relatively short times used in the present experiments, but it is uncertain whether they can completely restore a normal resting potential as well as a normal contracture after a depolarization due to a lack of Ca or an increase in [K]0. On whole toe muscles Frank (1962) found that several multivalent cations, including Be, Mg, and Zn, in the absence of Ca can restore the ability to develop tension after an increase in [K]O, but in every case only for a limited time.…”

Section: Discussionmentioning

confidence: 63%

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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: Resultssupporting

confidence: 91%

Section: Discussionmentioning

confidence: 63%

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

Lüttgau¹

1963

The Journal of Physiology

208

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“…Koketsu & Noda, 1962), whether or not calcium was present. DISCUSSION Further confirmation has been obtained of the observation that calcium deprivation can lead to a drastic fall of membrane potential in frog skeletal muscle (Bulbring et al 1956;Ishiko & Sato, 1957;Edman & Grieve, 1961). This occurs somewhat more rapidly when EDTA is present.…”

Section: Resultsmentioning

confidence: 55%

“…Frank (1958), using a paraffin-gap recording technique, reported that the depolarization produced by potassium chloride, and by implication the resting potential, was not affected by calcium depletion in the toe muscle of the frog. It is possible that the toe muscle is different in this respect to the frog sartorius muscle, in which the fall is now well documented (Bulbring et al 1956;Ishiko & Sato, 1957;Edman & Grieve, 1961;Koketsu & Noda, 1962); however, Curtis (1963) has also described a fall of resting potential in the toe muscle, using intracellular microelectrodes.…”

Section: Resultsmentioning

confidence: 99%

“…Edman & Grieve (1961) concluded that the strength of the mechanical responses to electrical stimulation was reduced in the absence of calcium in those fibres which remained excitable, but attributed this to a decrease in the size of the action potential. Curtis (1963) has described an inhibition of the potassium contracture in 100 jtM calcium without any significant change in resting potential.…”

Section: Resultsmentioning

confidence: 99%

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