Ca2 release via IP3Rs increases RyR mediated Ca2 spark frequency in ventricular cardiomyocytes without altering spark amplitude and duration

Abstract

Abstract Calcium plays critical roles in cardiac cells, coupling electrical excitation to mechanical contraction with each heartbeat, while simultaneously mediating biochemical signals that regulate cell growth. While ryanodine receptors (RyRs) are fundamental to generation of elementary calcium release events (sparks) and global calcium elevations that underlie excitation-contraction coupling (ECC), calcium release via inositol 1,4,5-trisphosphate receptors (IP 3 Rs) is also reported in cardiomyocytes. IP 3 R calcium release modifies ECC as well as contributing to downstream regulation of hypertrophic gene expression. Recent studies suggest that proximal localisation of IP 3 Rs with RyRs co..