Calcium movements inside the sarcoplasmic reticulum of cardiac myocytes

► Cardiac intra-sarcoplasmic reticulum (SR) free [Ca2 +] ([Ca2 +]SR), SR Ca2 + load and Ca2 + release ► [Ca2 +]SR changes during E-C coupling (Ca2 + scraps), Ca2 + sparks/blinks and Ca2 + waves. ► Spatiotemporal [Ca2 +]SR gradients constrain intra-SR Ca2 + diffusion models. ► Controversies about SR Ca2 + release activation, termination and wave propagation