Sarcoplasmic Reticulum
Sarcoplasmic Reticulum - Related Videos
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Optical Mapping of Intra-Sarcoplasmic Reticulum Ca2+ and Transmembrane Potential in the Langendorff-perfused Rabbit Heart
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Cited by 8 •
2015
This article describes the detailed protocol and equipment necessary for dual optical mapping of transmembrane potential (Vm) and free intra-sarcoplasmic reticulum (SR) Ca2+ in the Langendorff-perfused rabbit heart. This method allows for direct observation and quantification of Vm and SR Ca2+ dynamics in the intact heart.
11:00
Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes
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Cited by 18 •
2017
Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Here, we describe a protocol to evaluate sarcoplasmic reticulum Ca2+ reserve and diastolic calcium removal function in cardiomyocytes by a calcium imaging system.
10:05
Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging
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Cited by 1 •
2016
Currently, most available calcium indicators are used to quantify cytoplasmic calcium transients as indirect measures of calcium released from the sarcoplasmic reticulum in cultured smooth muscle cells. This protocol describes the use of a specific FRET-based indicator that allows direct measurement of calcium signals within the sarcoplasmic reticulum lumen.
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Visualization of Endoplasmic Reticulum Subdomains in Cultured Cells
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Cited by 3 •
2014
We describe the imaging approaches we use to investigate the distribution and mobility of the transfected fluorescent proteins resident in the endoplasmic reticulum (ER) by means of the confocal imaging of living cells. We also ultrastructurally analyze the effect of their expression on the architecture of this subcellular compartment.
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Endoplasmic Reticulum
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2026
Endoplasmic ReticulumThe endoplasmic reticulum (ER) is an extensive network of membranous sacs and tubules in eukaryotic cells, continuous with the outer membrane of the nucleus. This structural continuity integrates nuclear and cytoplasmic processes and facilitates efficient intracellular transport. This allows mRNA to move directly from the nucleus to ribosomes for efficient protein synthesis. As a result, the ER serves as a central site for the synthesis, processing, and distribution of...
FAQs
The action potential moves along the sarcolemma and into the transverse tubules, bringing electrical excitation close to calcium-release channels in the sarcoplasmic reticulum. This activation opens ryanodine receptors, allowing calcium to enter the cytoplasm. The increase in cytoplasmic calcium then enables actin-myosin interaction, linking membrane excitation to force production.
SERCA pumps remove calcium from the cytoplasm and return it to the sarcoplasmic reticulum after release. This lowers the calcium available to support actin-myosin interaction, allowing the muscle to relax. Their activity therefore completes the calcium cycle initiated by ryanodine receptor opening and helps maintain controlled transitions between contraction and relaxation.
Muscle function depends on the timing and balance of calcium movement. Release into the cytoplasm must provide enough calcium to initiate actin-myosin interaction, while reuptake must subsequently reduce cytoplasmic calcium to support relaxation. If this cycle is not controlled, the coordination between excitation, contraction, and relaxation that supports muscle activity can be disrupted.
A biological analysis can follow the sequence from an action potential, through the sarcolemma and transverse tubules, to ryanodine receptor activation, cytoplasmic calcium entry, actin-myosin interaction, and SERCA-mediated calcium return. Examining these linked stages shows how an electrical signal becomes mechanical activity and how the system restores conditions for relaxation.
The calcium-regulating cycle is relevant to skeletal, cardiac, and smooth muscle. In each case, the sarcoplasmic reticulum contributes to controlled calcium availability, connecting excitation with contraction and subsequent relaxation. Considering all three muscle types places this organelle within a broad biological context rather than limiting its importance to a single form of muscle tissue.
Studying calcium storage, release, and reuptake in the sarcoplasmic reticulum helps explain how excitation-contraction coupling supports normal muscle function. This knowledge is relevant to investigations of muscle disorders and cardiovascular disease. Because the calcium cycle contains distinct release and recovery processes, it also identifies mechanisms that may serve as potential therapeutic targets.