Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1970 Jul;209(1):179–186. doi: 10.1113/jphysiol.1970.sp009161

Miniature potentials in denervated slow muscle fibres of the frog

R Miledi, E Stefani
PMCID: PMC1396034  PMID: 5499040

Abstract

1. Pyriformis and iliofibularis muscles of the frog were studied with micro-electrodes. Both muscles contain a mixture of fast and slow muscle fibres, which can be distinguished by differences in their miniature end-plate potentials (min.e.p.p.s).

2. In addition, the membrane time constant of fast fibres is < 20 msec, while that of slow fibres is > 200 msec.

3. The characteristic difference in time constant persisted after denervation and allowed the identification of fibre type.

4. Denervated slow fibres had min.e.p.p.s of variable time courses and skew amplitude distributions. Their frequency was lower than in normally innervated fibres, and could be increased by hypotonic solutions.

5. In analogy with similar observations made previously in fast muscle fibres, it is suggested that after nerve degeneration the Schwann cells of small motor nerve fibres release packages of transmitter which give rise to min.e.p.p.s.

Full text

PDF
179

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. BIRKS R., KATZ B., MILEDI R. Physiological and structural changes at the amphibian myoneural junction, in the course of nerve degeneration. J Physiol. 1960 Jan;150:145–168. doi: 10.1113/jphysiol.1960.sp006379. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. BURKE W., GINSBORG B. L. The electrical properties of the slow muscle fibre membrane. J Physiol. 1956 Jun 28;132(3):586–598. doi: 10.1113/jphysiol.1956.sp005551. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. BURKE W. Spontaneous potentials in slow muscle fibres of the frog. J Physiol. 1957 Mar 11;135(3):511–521. doi: 10.1113/jphysiol.1957.sp005726. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. FATT P., KATZ B. Spontaneous subthreshold activity at motor nerve endings. J Physiol. 1952 May;117(1):109–128. [PMC free article] [PubMed] [Google Scholar]
  5. HUNT C. C., NELSON P. G. STRUCTURAL AND FUNCTIONAL CHANGES IN THE FROG SYMPATHETIC GANGLION FOLLOWING CUTTING OF THE PRESYNAPTIC NERVE FIBRES. J Physiol. 1965 Mar;177:1–20. doi: 10.1113/jphysiol.1965.sp007571. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. KUFFLER S. W., VAUGHAN WILLIAMS E. M. Properties of the 'slow' skeletal muscles fibres of the frog. J Physiol. 1953 Aug;121(2):318–340. doi: 10.1113/jphysiol.1953.sp004949. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. KUFFLER S. W., VAUGHAN WILLIAMS E. M. Small-nerve junctional potentials; the distribution of small motor nerves to frog skeletal muscle, and the membrane characteristics of the fibres they innervate. J Physiol. 1953 Aug;121(2):289–317. doi: 10.1113/jphysiol.1953.sp004948. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. MILEDI R. The acetylcholine sensitivity of frog muscle fibres after complete or partial devervation. J Physiol. 1960 Apr;151:1–23. [PMC free article] [PubMed] [Google Scholar]
  9. Miledi R., Slater C. R. Electrophysiology and electron-microscopy of rat neuromuscular junctions after nerve degeneration. Proc R Soc Lond B Biol Sci. 1968 Feb 27;169(1016):289–306. doi: 10.1098/rspb.1968.0012. [DOI] [PubMed] [Google Scholar]
  10. Stefani E., Steinbach A. B. Resting potential and electrical properties of frog slow muscle fibres. Effect of different external solutions. J Physiol. 1969 Aug;203(2):383–401. doi: 10.1113/jphysiol.1969.sp008869. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES