Effect of intracellular anisotropy on electrical source determination in a muscle fibre.


Journal Article

Expressions are available for describing, quantitatively, the source associated with an action potential propagating along an excitable fibre. For a nerve fibre one such expression defines an equivalent volume dipole density function tau(x) = -delta/delta x (sigma i phi i (x) - sigma e phi e (x)) ax (where x is the axial co-ordinate, i is the intracellular and e the extracellular region, sigma i and sigma e are isotropic conductivities, phi the potential at the membrane, while axial symmetry is assumed), and this source fills the intracellular region. This source, as distinct from transmembrane current formulations, lies in a uniform, isotropic, extracellular, medium. Consequently, for a fibre bundle a simple superposition of sources, all lying in a uniform, isotropic, extracellular space, can be accomplished. However, for muscle fibres the presence of non-conducting myofibrils causes the intracellular space to be anisotropic. The paper describes the modification in the aforementioned expressions for the case of longitudinal and transverse propagation and extrapolation to an arbitrary angle of propagation. The resultant source continues to be expressed relative to a uniform, isotropic, extracellular medium.

Full Text

Cited Authors

  • Plonsey, R

Published Date

  • July 1, 1990

Published In

Volume / Issue

  • 28 / 4

Start / End Page

  • 312 - 316

PubMed ID

  • 2246929

Pubmed Central ID

  • 2246929

Electronic International Standard Serial Number (EISSN)

  • 1741-0444

International Standard Serial Number (ISSN)

  • 0140-0118

Digital Object Identifier (DOI)

  • 10.1007/bf02446148


  • eng