Localization of the site of Ca2+ release at the level of a single sarcomere in skeletal muscle fibres.
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.
Escobar
A L
AL
Department of Physiology, University of California at Los Angeles 90024.
Monck
J R
JR
Fernandez
J M
JM
Vergara
J L
JL
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005453:Fluorescence; D007834:Lasers; D008853:Microscopy; D009132:Muscles / Q000378:metabolism*; D011892:Rana catesbeiana; D012518:Sarcomeres / Q000378:metabolism*
D002118:Calcium