BioMed Research International / 2009 / Article / Fig 2

Review Article

Role of Ryanodine Receptor Subtypes in Initiation and Formation of Calcium Sparks in Arterial Smooth Muscle: Comparison with Striated Muscle

Figure 2

Control of calcium sparks by voltage-dependent L-type calcium channels. (a) entry from extracellular space is not required for calcium release in skeletal muscle. Charge movement within C 1.1 activates RyR1 channel via a direct physical interaction. efflux from SR through the opened RyR1 channel activates nearby RyR (RyR3) channels via calcium-induced calcium release (CICR). (b) In cardiomyocytes C 1.2 mediates influx of extracellular into cytosol. then binds to and activates RyR2 channels via CICR. (c) Triggering of calcium sparks is not controlled by rapid, direct cross-talk between C 1.2 channels and RyRs in smooth muscle cells in contrast to cardiac and skeletal muscle cells. Instead, C 1.2 channels contribute to global cytosolic , which in turn influences luminal SR calcium and thus calcium sparks. SERCA: sarco/endoplasmic reticulum calcium ATPase, BK: big conductance calcium-activated channel.
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135249.fig.002b
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