Localization of the site of Ca2+ release at the level of a single sarcomere in skeletal muscle fibres

Nature. 1994 Feb 24;367(6465):739-41. doi: 10.1038/367739a0.


The development of mechanical force in skeletal muscle fibres is brought about by rapid increases in the intracellular calcium concentration (Ca2+ transients) which can be detected by optical methods. Local stimulation experiments and ultrastructural evidence suggest that, at a microscopic level, these Ca2+ transients are generated by the release of Ca2+ ions from the terminal cisternae of the sarcoplasmic reticulum in response to the depolarization of the transverse tubules (t-tubules). Nevertheless, to date, there is no functional information on the exact location at which Ca2+ release takes place. The present experiments were designed to obtain direct evidence about dynamic changes in localization and microscopic distribution of Ca2+ in a single sarcomere using two independent novel methodologies: confocal spot detection of Ca2+ transients and Ca2+ imaging with pulsed laser excitation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Action Potentials
  • Animals
  • Calcium / metabolism*
  • Fluorescence
  • Lasers
  • Microscopy
  • Muscles / metabolism*
  • Rana catesbeiana
  • Sarcomeres / metabolism*


  • Calcium