The effect of sodium ions on the electrical activity of the giant axon of the squid

Hodgkin, A. L.; Katz, Bernhard

doi:10.1113/jphysiol.1949.sp004310

Cited by 3,240 publications

(1,854 citation statements)

References 9 publications

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“…The calcium current in the model is governed by the Goldman-Hodgkin-Katz electrodiffusion model (Hille 2001;Goldman 1943;Hodgkin and Katz 1949), with the current described as:…”

Section: Discussionmentioning

confidence: 99%

Studies of stimulus parameters for seizure disruption using neural network simulations

et al. 2007

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A large scale neural network simulation with realistic cortical architecture has been undertaken to investigate the effects of external electrical stimulation on the propagation and evolution of ongoing seizure activity. This is an effort to explore the parameter space of stimulation variables to uncover promising avenues of research for this therapeutic modality. The model consists of an approximately 800 μm × 800 μm region of simulated cortex, and includes seven neuron classes organized by cortical layer, inhibitory or excitatory properties, and electrophysiological characteristics. The cell dynamics are governed by a modified version of the Hodgkin-Huxley equations in single compartment format. Axonal connections are patterned after histological data and published models of local cortical wiring. Stimulation induced action potentials take place at the axon initial segments, according to threshold requirements on the applied electric field distribution. Stimulation induced action potentials in horizontal axonal branches are also separately simulated. The calculations are performed on a 16 node distributed 32-bit processor system. Clear differences in seizure evolution are presented for stimulated versus the undisturbed rhythmic activity. Data is provided for frequency dependent stimulation effects demonstrating a plateau effect of stimulation efficacy as the applied frequency is increased from 60 Hz to 200 Hz. Timing of the stimulation with respect to the underlying rhythmic activity demonstrates a phase dependent sensitivity. Electrode height and position effects are also presented. Using a dipole stimulation electrode arrangement, clear orientation effects of the dipole with respect to the model connectivity is also demonstrated. A sensitivity analysis of these results as a function of the stimulation threshold is also provided.

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“…The calcium current in the model is governed by the Goldman-Hodgkin-Katz electrodiffusion model (Hille 2001;Goldman 1943;Hodgkin and Katz 1949), with the current described as:…”

Section: Discussionmentioning

confidence: 99%

Studies of stimulus parameters for seizure disruption using neural network simulations

et al. 2007

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“…The relationship is linear and the reversal potential is 6 mV. A permeability ratio, Pc/P• of 2.1 was obtained using the Goldman-Hodgkin-Katz equation [19].…”

Section: MVmentioning

confidence: 99%

The major Thiobacillus ferrooxidans outer membrane protein forms low conductance ion channels in planar lipid bilayers

et al. 1992

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A protein i,~olated at~d purified from the outer membrane of the aeidophilic, chemolithotrophic bacterium, Thiobaciflus fi, rrooxidans with an oligomeric molecular weight of 90 000 Da (pg0) was incorporated into phosphatldylethanolamine planar lipid bilayers. The protein formed slightly anionic channels in KCI solutions, with a conductance of 25 pS in 100 mM KCI. The current-voltage relationship was linear between ±60 mV, and the conductance was a saturating function of the salt concentration. These channels fluctuated from a single open to closed state at low potentials, but present ftlckerin~ activity at higher potentials.

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“…6), which gives a permeability coefficient (PG of 5.3 • 10 -~7 liter/sec, calculated from the Goldman-Hodgkin-Katz equation (Goldman, 1943;Hodgkin & Katz, 1949) and Ca -~+ activity of 28.5 raM. In asymmetrical solution (136:50 mM CaCI2), the relationship showed rectification, with a reversal potential of -16 inV.…”

Section: Equinatoxin II F O R M S C a 2 + -P E R M E A B L E C H A Nmentioning

confidence: 99%

Cytotoxicity of equinatoxin II from the sea anemoneActinia equina involves ion channel formation and an increase in intracellular calcium activity

et al. 1990

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Summary.Equinatoxin 11 is a 20-kDa basic protein isolated from the sea anemone Actinia equina. The aim of our work was to investigate the primary molecular basis for the cytotoxic effects ofequinatoxin 11 in two model systems: single bovine lactotrophs and planar lipid bilayers. Previous work has shown that equinatoxin II produces rapid changes in cell morphology, which are dependent on external calcium. It has also been reported that addition of equinatoxin II increases membrane electrical conductance, which suggests that the cytotoxic action of equinatoxin II involves an increase in the permeability of membranes to Ca :+ , Extensive changes in cytosolic Ca -'+ activity are thought to invoke irreversible changes in cell physiology and morphology. In this paper, we show that morphological changes brought about by equinatoxin II in bovine lactotrophs are associated with a rapid rise in cytosolic Ca -'+ activity, monitored with a fura-2 video imaging apparatus. Moreover, incorporation of equinatoxin II into planar lipid bilayers produces Ca -'+ permeable ion channels. This suggests that the mode of equinatoxin II cytotoxicity involves the formation of cation (Ca -,+ ) permeable channels in cell membranes. Key Wordsfura-2 imaging, planar lipid bilayers -Ca channels 9 bovine lactotrophs 9 equinatoxin -sea anemone. Aclinia eqtdna

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The effect of sodium ions on the electrical activity of the giant axon of the squid

Cited by 3,240 publications

References 9 publications

Studies of stimulus parameters for seizure disruption using neural network simulations

Studies of stimulus parameters for seizure disruption using neural network simulations

The major Thiobacillus ferrooxidans outer membrane protein forms low conductance ion channels in planar lipid bilayers

Cytotoxicity of equinatoxin II from the sea anemoneActinia equina involves ion channel formation and an increase in intracellular calcium activity

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