Quantitative Measurement of Ca^sup 2+^ in the Sarcoplasmic Reticulum Lumen of Mammalian Skeletal Muscle

• Published in: Biophysical journal Vol. 99; no. 8; p. 2705
• Main Authors: Ziman, Andrew P, Ward, Christopher W, Rodney, George G, Lederer, W Jonathan, Bloch, Robert J
• Format: Journal Article
• Language: English
• Published: New York Biophysical Society 20-10-2010
• Subjects: Biophysics; Calcium; Mammals; Measurement; Methods; Musculoskeletal system
• ISSN: 0006-3495; 1542-0086

Skeletal muscle stores ... in the sarcoplasmic reticulum (SR) and releases it to initiate contraction, but the concentration of luminal ... in the SR (...) and the amount that is released by physiological or pharmacological stimulation has been difficult to measure. Here we present a novel, yet simple and direct, method that provides the first quantitative estimates of static content and dynamic changes in ... in mammalian skeletal muscle, to our knowledge. The method uses fluo-5N loaded into the SR of single, mammalian skeletal muscle cells (murine flexor digitorum brevis myofibers) and confocal imaging to detect and calibrate the signals. Using this method, we have determined that ... is 390 ...M. 4-Chloro-m-cresol, an activator of the skeletal muscle ryanodine receptor, reduces ... to ...8 ...M, when values are corrected for background fluorescence from cytoplasmic pools of dye. Prolonged electrical stimulation (10 s) at 50 Hz releases 88% of the SR ... content, whereas stimulation at 1 Hz (10 s) releases only 20%. Our results lay the foundation for molecular modeling of the dynamics of luminal SR ... and for future studies of the role of SR ... in healthy and diseased mammalian muscle. (ProQuest: ... denotes formulae/symbols omitted.)