Composition of Vacuoles and Sarcoplasmic Reticulum in Fatigued Muscle: Electron Probe Analysis

Electron probe analysis, cryo-ultramicrotomy, and freeze-substitution were used to determine the nature of vacuolation and the subcellular composition in fatigued frog skeletal muscle fibers. The vacuoles caused by fatigue were part of the T-tubule system and contained high concentrations of NaCl. T...

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Veröffentlicht in:Proceedings of the National Academy of Sciences - PNAS 1978-03, Vol.75 (3), p.1329-1333
Hauptverfasser: Gonzalez-Serratos, Hugo, Somlyo, Avril V., McClellan, George, Shuman, Henry, Borrero, Luis M., Somlyo, Andrew P.
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Sprache:eng
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Zusammenfassung:Electron probe analysis, cryo-ultramicrotomy, and freeze-substitution were used to determine the nature of vacuolation and the subcellular composition in fatigued frog skeletal muscle fibers. The vacuoles caused by fatigue were part of the T-tubule system and contained high concentrations of NaCl. The calcium concentration in the terminal cisternae was higher than previously measured normal resting values. Mitochondrial calcium content was relatively low (mean ± SEM, 2 ± 2 mmol/kg dry weight). Fiber NaCl was increased. It is concluded that fatigue is not due to the depletion of calcium stores from the terminal cisternae or to uncoupling of mitochondria due to calcium loading but may be caused by multiple mechanisms including failure of the T-tubule action potential.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.75.3.1329