Journal ArticleDOI
Relating the Sodium Current and Conductance to the Shape of Transmembrane and Extracellular Potentials by Simulation: Effects of Propagation Boundaries
TLDR
The results show that the shape of the transmembrane potential and the kinetics of the sodium current and conductance are highly determined by boundary effects at sites where impulse conduction begins and where it ends at a collision or an anatomical end.Abstract:
The purpose of this paper is to describe how the transmembrane and extracellular potential waveforms, and their derivatives, are related to each other and to the sodium current and conductance in propagating cardiac action potentials. The results show that the shape of the transmembrane potential and the kinetics of the sodium current and conductance are highly determined by boundary effects at sites where impulse conduction begins and where it ends at a collision or an anatomical end. These propagation nonuniformities produced a relationship between Vmax and the internal membrane variables gNa and INa that is just the opposite of the classical relation between Vmax and the magnitude of the sodium current. For example, in these cases, both peak INa and the area under the gNa curve decreased when Vmax increased. In addition, Vmax, was shown to coincide in time with the maximum rate of increase of gNa and INa. The maximum negative slope of the extracellular waveform coincided in time with Vmax of the transmembrane potential for all shapes of the waveforms. Therefore, either the maximum negative slope of the extracellular waveform or Vmax of the action potential provides a time marker for the same underlying depolarizing event, i.e., the maximum rate of increase of the depolarizing current and its conductance.read more
Citations
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Journal ArticleDOI
Applied Numerical Analysis. By C.F. Gerald. Pp. xii, 340. £3·60. 1970. (Addison-Wesley.)
Journal ArticleDOI
Basic Mechanisms of Cardiac Impulse Propagation and Associated Arrhythmias
André G. Kléber,Yoram Rudy +1 more
TL;DR: This review attempts to synthesize results from computer simulations and experimental preparations to define mechanisms and biophysical principles that govern normal and abnormal conduction in the heart.
Journal ArticleDOI
Relating extracellular potentials and their derivatives to anisotropic propagation at a microscopic level in human cardiac muscle. Evidence for electrical uncoupling of side-to-side fiber connections with increasing age.
Madison S. Spach,Paul C. Dolber +1 more
TL;DR: The relationships between the time derivatives of the extracellular waveforms and the underlying action potentials in the experimental analysis of anisotropic propagation at this small size scale are demonstrated, and these relationships are applied to human atrial muscle at different ages.
Journal ArticleDOI
Analysis of Models for External Stimulation of Axons
TL;DR: The activating function is discussed for monopolar electrodes but the principle can be extended to arbitrary configurations of electrodes and the activity of the axon depends on the second space derivative of the extracellular medium.
Journal ArticleDOI
Correlation between in vivo transmembrane action potential durations and activation-recovery intervals from electrograms. Effects of interventions that alter repolarization time.
C W Haws,Robert L. Lux +1 more
TL;DR: Classic cable theory was used to analyze the relation between the activation-recovery interval measured from unipolar electrograms and transmembrane action potential duration and there was close correlation between activation- recovery intervals taken during cardiac sympathetic nerve stimulation and local epicardial warming.
References
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A quantitative description of membrane current and its application to conduction and excitation in nerve
A. L. Hodgkin,A. F. Huxley +1 more
TL;DR: This article concludes a series of papers concerned with the flow of electric current through the surface membrane of a giant nerve fibre by putting them into mathematical form and showing that they will account for conduction and excitation in quantitative terms.
Journal ArticleDOI
The effect of sodium ions on the electrical activity of the giant axon of the squid
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A practical method for numerical evaluation of solutions of partial differential equations of the heat-conduction type
TL;DR: In this paper, the authors present methods of evaluating numerical solutions of the non-linear partial differential equation to the boundary conditions A, k, q are known constants, where q is the rate of heat generation.
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Total Excitation of the Isolated Human Heart
Dirk Durrer,R. Th. Van Dam,Gerrit E. Freud,Michiel J. Janse,Frits L. Meijler,R. C. Arzbaecher +5 more
TL;DR: In this paper, isolated human heart measurements were made from as many as 870 intramural terminals to obtain information concerning the time course and instantaneous distribution of the excitatory process of the normal human heart.
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