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Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging
Published on: June 20, 2016
The luminal Ca2+ transient controls Ca2+ release/re-uptake of sarcoplasmic reticulum
1Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA.
Abstract:
Our recent study (Saiki, Y., and Ikemoto, N., Biochemistry 38, 3112-3119, 1999) suggests that Ca2+ release and re-uptake of the released Ca2+ are coordinated. The following results suggest that the coordination is mediated by the luminal Ca2+ ([Ca2+]lum) transient. Upon inducing the release of the passively loaded Ca2+ from the SR with polylysine, the luminal Ca2+ ([Ca2+]lum) first increased then decreased ([Ca2+]lum transient). The activity of the SR Ca2+ ATPase was monitored at different times after inducing Ca2+ release. The phosphoenzyme (EP) formation as determined by the MANT-fluorescence increased concurrently with the initial rapid increase in the [Ca2+]lum. EP decay (pumping turnover) was accelerated concurrently with a decrease of the [Ca2+]lum. The results suggest that the [Ca2+]lum transient serves as a mediator for the acceleration of the Ca2+ re-uptake occurring soon after the induction of Ca2+ release.
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