Abstract
1. Ephaptic transmission was observed between spontaneously active single nerve fibres in the spinal nerve roots of dystrophic mice. 2. In the five ephaptically interacting pairs of fibres studied in detail, the conduction velocities in the exciting fibres were < 1 m/sec and the conduction velocities in the excited fibres were 2-10 m/sec in the immediate vicinity of the ephapses at 26-28 degrees C. 3. Membrane current analysis suggested that conduction was continuous in the exciting fibres. In some cases conduction away from the ephapse in the excited fibre was saltatory in at least one and possibly in both directions of transmission. 4. It is concluded that in at least some cases the direction of ephaptic transmission is from bare axon to myelinated axon. 5. Transmission time across the ephapses, measured as the interval between peaks of inward membrane current in exciting and excited fibres, was less than or equal to microseconds-240 microseconds. 6. Ephaptic transmission is not necessarily contingent upon the direction of propagation of the impulse in the exciting fibre. 7. Ephaptic transmission between two fibres can remain stable at frequencies of at least 70 Hz. 8. There may be multiple sites of spontaneous ectopic excitation in single dystrophic mouse spinal root axons. An impulse traversing a site of ectopic excitation may incite a subsequent burst of impulses to arise from that site following a delay of more than 100 msec.
Full text
PDFSelected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bennett M. V. Physiology of electrotonic junctions. Ann N Y Acad Sci. 1966 Jul 14;137(2):509–539. doi: 10.1111/j.1749-6632.1966.tb50178.x. [DOI] [PubMed] [Google Scholar]
- Bostock H., Sears T. A. Continuous conduction in demyelinated mammalian nerve fibers. Nature. 1976 Oct 28;263(5580):786–787. doi: 10.1038/263786a0. [DOI] [PubMed] [Google Scholar]
- Bostock H., Sears T. A. The internodal axon membrane: electrical excitability and continuous conduction in segmental demyelination. J Physiol. 1978 Jul;280:273–301. doi: 10.1113/jphysiol.1978.sp012384. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bradley W. G., Jenkison M. Abnormalities of peripheral nerves in murine muscular dystrophy. J Neurol Sci. 1973 Feb;18(2):227–247. doi: 10.1016/0022-510x(73)90009-9. [DOI] [PubMed] [Google Scholar]
- Bray G. M., Aguayo A. J. Quantitative ultrastructural studies of the axon Schwann cell abnormality in spinal nerve roots from dystrophic mice. J Neuropathol Exp Neurol. 1975 Nov;34(6):517–530. doi: 10.1097/00005072-197511000-00006. [DOI] [PubMed] [Google Scholar]
- Bray G. M., Perkins S., Peterson A. C., Aguayo A. J. Schwann cell multiplication deficit in nerve roots of newborn dystrophic mice. A radioautographic and ultrastructural study. J Neurol Sci. 1977 Jun;32(2):203–212. doi: 10.1016/0022-510x(77)90235-0. [DOI] [PubMed] [Google Scholar]
- Clark J. W., Jr, Plonsey R. Fiber interaction in a nerve trunk. Biophys J. 1971 Mar;11(3):281–294. doi: 10.1016/S0006-3495(71)86214-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Clark J. W., Plonsey R. A mathematical study of nerve fiber interaction. Biophys J. 1970 Oct;10(10):937–957. doi: 10.1016/S0006-3495(70)86344-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Eberstein A., Goodgold J., Pachter B. R. Effect of curare on electromyographic and contractile responses in the myotonic mouse. Exp Neurol. 1975 Nov;49(2):612–616. doi: 10.1016/0014-4886(75)90115-6. [DOI] [PubMed] [Google Scholar]
- FRANKENHAEUSER B., HODGKIN A. L. The after-effects of impulses in the giant nerve fibres of Loligo. J Physiol. 1956 Feb 28;131(2):341–376. doi: 10.1113/jphysiol.1956.sp005467. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Granit R., Skoglund C. R. Facilitation, inhibition and depression at the ;artificial synapse' formed by the cut end of a mammalian nerve. J Physiol. 1945 Mar 28;103(4):435–448. doi: 10.1113/jphysiol.1945.sp004089. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hasty D. L., Hay E. D. Freeze-fracture studies of the developing cell surface. II. Particle-free membrane blisters on glutaraldehyde-fixed corneal fibroblasts are artefacts. J Cell Biol. 1978 Sep;78(3):756–768. doi: 10.1083/jcb.78.3.756. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hodgkin A. L. Evidence for electrical transmission in nerve: Part I. J Physiol. 1937 Jul 15;90(2):183–210. doi: 10.1113/jphysiol.1937.sp003507. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hodgkin A. L. Evidence for electrical transmission in nerve: Part II. J Physiol. 1937 Jul 15;90(2):211–232. doi: 10.1113/jphysiol.1937.sp003508. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huizar P., Kuno M., Miyata Y. Electrophysiological properties of spinal motoneurones of normal and dystrophic mice. J Physiol. 1975 Jun;248(1):231–246. doi: 10.1113/jphysiol.1975.sp010971. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huxley A. F., Stämpfli R. Evidence for saltatory conduction in peripheral myelinated nerve fibres. J Physiol. 1949 May 15;108(3):315–339. [PMC free article] [PubMed] [Google Scholar]
- Katz B., Schmitt O. H. Electric interaction between two adjacent nerve fibres. J Physiol. 1940 Feb 14;97(4):471–488. doi: 10.1113/jphysiol.1940.sp003823. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kuffler S. W., Nicholls J. G. The physiology of neuroglial cells. Ergeb Physiol. 1966;57:1–90. [PubMed] [Google Scholar]
- Medina J. L., Chokroverty S., Reyes M. Localized myokymia caused by peripheral nerve injury. Arch Neurol. 1976 Aug;33(8):587–588. doi: 10.1001/archneur.1976.00500080065011. [DOI] [PubMed] [Google Scholar]
- Ramón F., Moore J. W. Ephaptic transmission in squid giant axons. Am J Physiol. 1978 May;234(5):C162–C169. doi: 10.1152/ajpcell.1978.234.5.C162. [DOI] [PubMed] [Google Scholar]
- Rasminsky M. Ectopic generation of impulses and cross-talk in spinal nerve roots of "dystrophic" mice. Ann Neurol. 1978 Apr;3(4):351–357. doi: 10.1002/ana.410030413. [DOI] [PubMed] [Google Scholar]
- Rasminsky M., Kearney R. E., Aguayo A. J., Bray G. M. Conduction of nervous impulses in spinal roots and peripheral nerves of dystrophic mice. Brain Res. 1978 Mar 17;143(1):71–85. doi: 10.1016/0006-8993(78)90753-9. [DOI] [PubMed] [Google Scholar]
- Rasminsky M., Sears T. A. Internodal conduction in undissected demyelinated nerve fibres. J Physiol. 1972 Dec;227(2):323–350. doi: 10.1113/jphysiol.1972.sp010035. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Seltzer Z., Devor M. Ephaptic transmission in chronically damaged peripheral nerves. Neurology. 1979 Jul;29(7):1061–1064. doi: 10.1212/wnl.29.7.1061. [DOI] [PubMed] [Google Scholar]
- Stirling C. A. Abnormalities in Schwann cell sheaths in spinal nerve roots of dystrophic mice. J Anat. 1975 Feb;119(Pt 1):169–180. [PMC free article] [PubMed] [Google Scholar]
- Wallis W. E., Van Poznak A., Plum F. Generalized muscular stiffness, fasciculations, and myokymia of peripheral nerve origin. Arch Neurol. 1970 May;22(5):430–439. doi: 10.1001/archneur.1970.00480230048005. [DOI] [PubMed] [Google Scholar]
- Wasserstrom W. R., Starr A. Facial myokymia in the Guillain-Barré syndrome. Arch Neurol. 1977 Sep;34(9):576–577. doi: 10.1001/archneur.1977.00500210078016. [DOI] [PubMed] [Google Scholar]
- Welch L. K., Appenzeller O., Bicknell J. M. Peripheral neuropathy with myokymia, sustained muscular contraction, and continuous motor unit activity. Neurology. 1972 Feb;22(2):161–169. doi: 10.1212/wnl.22.2.161. [DOI] [PubMed] [Google Scholar]