Resting potential and electrical properties of frog slow muscle fibres. Effect of different external solutions

Stefani, Enrico; Steinbach, Alan

doi:10.1113/jphysiol.1969.sp008869

Cited by 133 publications

(105 citation statements)

References 25 publications

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“…5A also shows the effects of isotonic Ca solution on the voltage-current relationship (open circles). As in frog slow or tonic muscle fibres an elevated Ca concentration in the bathing saline produced a marked increase of the membrane resistance (Stefani & Steinbach, 1969). The time constant of the cell membrane, Tm) was 29-8 + 4-8 msec (six fibres) in normal saline.…”

Section: Resultsmentioning

confidence: 89%

“…In this case the above given value of %m would be over-estimated since the percentage of the final value of the voltage deflexion at which %m should be measured is less than 84 % and depends on the ratio between the length of the fibres and their space constant (Stefani & Steinbach, 1969). To short cable model is more suitable for these fibres it is necessary to know their space constant, a parameter not measured in these experiments.…”

Section: Electrical Properties Of Extraocular Muscles 459mentioning

confidence: 99%

“…The attenuating influence of such a shunt on Erp should be noticeable in these muscle cells because thev have a relativeely high Reir. Stefani & Steinbach (1969) and Hodgkin & Nakajima (1972) have discussed the effects of micro-electrode shunt on Erp in the case of frog muscle fibres.…”

Section: Electrical Properties Of Extraocular Musclesmentioning

confidence: 99%

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Electrophysiological identification of two types of fibres in rat extraocular muscles.

Chiarandini¹,

Stefani²

1979

The Journal of Physiology

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SUMMARY1. The synaptic potentials and electrical properties of rat inferior rectus muscles were examined in vitro.2. In most fibres the spontaneous synaptic activity consisted of typical miniature end-plate potentials which had a normal distribution of amplitudes and rather uniform time courses. Suprathreshold and maximal nerve stimulation evoked unitary end-plate potentials (e.p.p.s). The synaptic activity of these fibres could be recorded only in the innervation zone of the muscle. These fibres were identified as being focally innervated.3. Focally innervated fibres gave action potentials upon direct and indirect stimulation. They had an effective resistance (Reff) of 1'62 + 022 MQ (mean + S.E., twenty-two fibres) and a time constant (Tm) of 3-8 + 04 msec (twenty-one fibres).Voltage-current curves in control saline were linear between membrane potentials of -50 to -140mV. 4. In a small number of fibres the spontaneous synaptic activity consisted of miniature small-nerve junction potentials which had a skewed distribution of amplitudes with predominance of smaller voltages and time courses with a wide range of variation. Nerve stimulation evoked composite small-nerve junction potentials (s.j.p.s) which could be resolved into unitary components by varying the strength of stimulation. S.j.p.s had a higher threshold than e.p.p.s. Synaptic potentials could be recorded outside the innervation zone, at various sites along the muscle length. These fibres were recognized as being multiply innervated with polyneuronal innervation.5. Multiply innervated fibres lacked action potentials, had a large Reff of 6-0 + 1-1 MD (six fibres) and a prolonged Tm of 29-8 + 4*8 msec. Reff show a moderate decrease to hyperpolarization and a rather large decrease to depolarization which denote, respectively, the presence of anomalous and delayed rectification.6. It is concluded that rat extraocular muscles contain at least two populations of muscle fibres that in terms of synaptic activity and electrical properties are comparable to twitch fibres of other mammalian muscles and to slow or tonic fibres of amphibians.

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Section: Resultsmentioning

confidence: 89%

Section: Electrical Properties Of Extraocular Muscles 459mentioning

confidence: 99%

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Electrophysiological identification of two types of fibres in rat extraocular muscles.

Chiarandini¹,

Stefani²

1979

The Journal of Physiology

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“…(iii) The values of the characteristic constants of mammalian striated muscle are much closer to those observed in the frog slow muscle fibres. (iv) The resting membrane potentials of the mammalian striated muscles are lower than those observed in the frog twitch muscle fibres (KATZ, 1948;ADRIAN and PEACHEY, 1965;STEFANI and STEINBACH, 1969).…”

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confidence: 89%

The Membrane Properties, and Excitationcontraction Coupling of M. Digastricus of the Guinea Pig

Ohbu

1972

Jpn.J.Physiol

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“…There are many studies on conduction velocity (CV) of impulses along muscle fibers (HAKANSSON,1956(HAKANSSON, , 1957MARTIN, 1954) and electrical constants of muscle fiber membrane (ADRIAN and PEACHEY, 1965;DULHUNTY and GAGE, 1973;DULHUNTY and FRANZINI-ARMSTRONG, 1977;FREYGANG et al, 1967;GAGE and EISENBERG, 1969a, b;STEFANI and STEINBACH, 1963). Little attention, except for one report, has been paid to relations between CV and the membrane constants.…”

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confidence: 99%

Effects of electrical constants on conduction velocity of action potentials measured with unidimensional latency-topography in frog skeletal muscle fibers.

et al. 1983

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1. Conduction velocity (CV) of an action potential recorded from a single muscle fiber of the frog was measured with a new method, unidimensional latency-topography, and electrical membrane constants were determined for the same muscle fiber. CV= 1.96±0.27 m/sec (n=52) at about 20°C. Temperature coefficient of CV: Q1=2.0. Electrical membrane constants in the same muscle fibers (n=52): A_ 3.25±0.83 mm, v=33.4±14.3 msec, Cm=6.09±2.13 ,uF/cm2, D=129.4 ±28.9 ,um (mean±S.D.). 2. The CV decreased linearly with increment of time constant, z, and membrane capacity per unit area, Cm. The space constant, A, and the fiber diameter of the muscle fiber, D, did not correlate with CV. It was concluded that the T-system, which contributes largely to membrane capacity, has a great influence on the CV.

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Resting potential and electrical properties of frog slow muscle fibres. Effect of different external solutions

Cited by 133 publications

References 25 publications

Electrophysiological identification of two types of fibres in rat extraocular muscles.

Electrophysiological identification of two types of fibres in rat extraocular muscles.

The Membrane Properties, and Excitationcontraction Coupling of M. Digastricus of the Guinea Pig

Effects of electrical constants on conduction velocity of action potentials measured with unidimensional latency-topography in frog skeletal muscle fibers.

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