Is muscle contraction initiated by internal current flow?

Sten‐Knudsen, O.

doi:10.1113/jphysiol.1960.sp006444

Cited by 34 publications

(14 citation statements)

References 17 publications

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“…Thus our TMP measurements strongly support the model of a cable structure-field interaction mechanism (Sten-Knudsen, 1960;Ranck, 1975;Chan & Nicholson, 1986;Tranchina & Nicholson, 1986). On an intuitive level, the model can be visualized as predicting the TMP to arise (in addition to the resting potential) from the difference between two voltage gradients set up by the passage of a current through nervous tissue, which causes ohmic potential drops in two conductive compartments.…”

Section: Discussionmentioning

confidence: 66%

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Effects of electric fields on transmembrane potential and excitability of turtle cerebellar Purkinje cells in vitro.

Chan

Hounsgaard

Nicholson

1988

The Journal of Physiology

172

147

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SUMMARY1. Transmembrane potential (TMP) responses of Purkinje cells (PCs) in isolated turtle cerebellum to externally applied quasi-steady-state electric fields aligned with the dendritic axis were continuously measured using simultaneous intracellular and extracellular recording. TMP was obtained by subtraction of extracellular voltage fields from intracellular potential recorded at the same depth in the cerebellum.2. The applied field changed the TMP with the polarity and amplitude dependent on the location on the PC membrane. This response at a given location increased linearly with external field up to a threshold level, beyond which active responses appeared.3. The basic effect on TMP consisted of depolarization in the half of the dendrite towards which the fields were directed, and hyperpolarization in the other half. A pooled TMP depth-profile shows a steady increase in polarization from the middle of the molecular layer towards each end. This profile correlates with that predicted from previously proposed cable models, giving them empirical support for the first time.4. Active responses were triggered by the field-induced depolarization. Tetrodotoxin (TTX)-sensitive action potentials arose with the primary depolarization in the somatic region. Notched, Ca2+-dependent action potentials arose with primary depolarization in the distal and mid-dendritic regions.5. A TTX-sensitive voltage plateau was triggered by TMP-depolarization in the proximal region. It in turn activated Na+-spike trains. The frequency of spiking was proportional to the external field. At around 160 spikes/s, the Na+ spikes inactivated, and the TMP level rose to a more depolarized plateau. This latter plateau was also TTX-sensitive.6. During depolarization of the distal dendritic region, sometimes a Ca21_ dependent plateau was observed. It appears to be associated with a small conductance increase.7. Field-induced hyperpolarization suppressed local spiking and voltage plateaux, t Present address, to which reprint requests should be sent:

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Section: Discussionmentioning

confidence: 66%

“…But these studies lacked rigorous definition of the field or its mode of action on neurones. These experimental efforts were supplemented by some theoretical studies of the issues involved (Sten-Knudsen, 1960;Ranck, 1975).…”

Section: Introductionmentioning

confidence: 99%

Effects of electric fields on transmembrane potential and excitability of turtle cerebellar Purkinje cells in vitro.

Chan

Hounsgaard

Nicholson

1988

The Journal of Physiology

172

147

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“…For constant fields, the effect on v m is determined by Equation 5 for an external field of large characteristic length along the cable (Fig. 2 A1,2, blue and red lines) (Sten-Knudsen, 1960;Ranck, 1963;Chan and Nicholson, 1986). For spatially inhomogeneous fields, the impact on v m is more complicated and depends on the cable-field alignment as well as on three length constants: the characteristic length of the external field ( s ), the cable length (l ), and the electrotonic length ( el ).…”

Section: Discussionmentioning

confidence: 99%

The Effect of Spatially Inhomogeneous Extracellular Electric Fields on Neurons

Anastassiou¹,

Montgomery²,

Barahona³

et al. 2010

J. Neurosci.

180

154

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The cooperative action of neurons and glia generates electrical fields, but their effect on individual neurons via ephaptic interactions is mostly unknown. Here, we analyze the impact of spatially inhomogeneous electric fields on the membrane potential, the induced membrane field, and the induced current source density of one-dimensional cables as well as morphologically realistic neurons and discuss how the features of the extracellular field affect these quantities. We show through simulations that endogenous fields, associated with hippocampal theta and sharp waves, can greatly affect spike timing. These findings imply that local electric fields, generated by the cooperative action of brain cells, can influence the timing of neural activity.

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“…The mechanisms involved in K contractures are generally taken to be very closely related to, if not identical with, the mechanism of the twitch. However, conditions have been reported under which either the twitch or the K contracture, but not both, is inhibited (Csapo & Suzuki, 1958;Sten-Knudsen, 1960;Sandow, 1955;Fujino & Fujino, 1964). Lorkovic (1962) concluded that K contractures, unlike twitches, were dependent upon influx of extracellular Ca.…”

Section: Discussionmentioning

confidence: 99%

A lesion of the transverse tubules of skeletal muscle

Howell¹

1969

The Journal of Physiology

136

102

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SUMMARY1. A method is described by which a selective lesion can be made in vitro in the transverse tubules of frog skeletal muscle.2. The method consists of exposing the muscle for 1 hr or more to a buffered salt solution made hypertonic by the inclusion of 400 mm glycerol and then returning the muscle to an isotonic salt solution. The lesion is induced during the washout of the glycerol.3. Electron micrographs reveal that the lesion consists of a rearrangement of the T-system membranes in such a way that the continuity of the tubules is lost. The membranes appear to coalesce into large vesicles scattered irregularly throughout the sarcoplasm.4. The glycerol treatment results in a depression of the resting potential of up to 30 mV. The treated fibres are depolarized by high concentrations of K as are normal muscle fibres.5. T-tubule lesioned fibres are unable to respond mechanically either to electrical stimulation or to elevated K but they do contract in the presence of caffeine and relax when the caffeine is removed.6. Problems concerning the variability of the procedure are presented and certain considerations concerning the mechanism of the effect are discussed.

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Is muscle contraction initiated by internal current flow?

Cited by 34 publications

References 17 publications

Effects of electric fields on transmembrane potential and excitability of turtle cerebellar Purkinje cells in vitro.

Effects of electric fields on transmembrane potential and excitability of turtle cerebellar Purkinje cells in vitro.

The Effect of Spatially Inhomogeneous Extracellular Electric Fields on Neurons

A lesion of the transverse tubules of skeletal muscle

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