Excitation-Contraction Coupling in Skeletal Muscle: Blockade by High Extracellular Concentrations of Calcium Buffers
- 16 June 1978
- journal article
- research article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 200 (4347) , 1270-1272
- https://doi.org/10.1126/science.96524
Abstract
High concentrations (80 to 90 millimolar) of the calcium buffers EGTA and citrate (less than 10(-7) molar free calcium ion) reversibly block excitation-contraction coupling in intact frog skeletal fibers, but do not block caffeine-induced contractures. Solutions containing the same free calcium concentration but lower concentrations of calcium buffer (1 millimolar) do not block excitation-contraction coupling. These results suggest that excitation-contraction coupling requires the presence of calcium in a "protected" extracellular compartment, probably the transverse tubular network, and that calcium is actively transported into this compartment from the muscle cell cytoplasm.Keywords
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