Role of inositol 1,4,5-trisphosphate in the regulation of ventricular Ca2Â + signaling in intact mouse heart

► Caged-InsP3 photolysis affects intracellular [Ca2+] in intact, beating hearts. ► InsP3 photolysis induced Ca2+ release in endothelial cells and epicardial myocytes. ► In ventricular myocytes, Ca2+ increase due to InsP3 photolysis did not impact ECC. ► InsP3 activates intracellular Ca2+ stores that share InsP3R and RyR.