کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2070222 | 1078476 | 2011 | 18 صفحه PDF | دانلود رایگان |

During excitation–contraction coupling in skeletal muscle, calcium ions are released into the myoplasm by the sarcoplasmic reticulum (SR) in response to depolarization of the fibre’s exterior membranes. Ca2+ then diffuses to the thin filaments, where Ca2+ binds to the Ca2+ regulatory sites on troponin to activate muscle contraction. Quantitative studies of these events in intact muscle preparations have relied heavily on Ca2+-indicator dyes to measure the change in the spatially-averaged myoplasmic free Ca2+ concentration (Δ[Ca2+]) that results from the release of SR Ca2+. In normal fibres stimulated by an action potential, Δ[Ca2+] is large and brief, requiring that an accurate measurement of Δ[Ca2+] be made with a low-affinity rapidly-responding indicator. Some low-affinity Ca2+ indicators monitor Δ[Ca2+] much more accurately than others, however, as reviewed here in measurements in frog twitch fibres with sixteen low-affinity indicators. This article also examines measurements and simulations of Δ[Ca2+] in mouse fast-twitch fibres. The simulations use a multi-compartment model of the sarcomere that takes into account Ca2+’s release from the SR, its diffusion and binding within the myoplasm, and its re-sequestration by the SR Ca2+ pump. The simulations are quantitatively consistent with the measurements and appear to provide a satisfactory picture of the underlying Ca2+ movements.
Journal: Progress in Biophysics and Molecular Biology - Volume 105, Issue 3, May 2011, Pages 162–179