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 C1.1 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 C1.2 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 C1.2 channels and RyRs in smooth muscle cells in contrast to cardiac and skeletal muscle cells. Instead, C1.2 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.
