How does the heart first start to beat?

Initiation of the first heartbeat; from single cell calcium oscillations to propagating waves

The heart is the first organ to form in an embryo, and must begin to pump early, but exactly how it first starts to beat is not understood. We know that the beating of the heart is caused by calcium, which moves in and out of cells and triggers muscles of the heart to contract. But for the heart to pump blood properly, all the muscles need to contract at the same time, and this requires the coordinated movement of calcium. Dr Richard Tyser has previously shown that, before the first heartbeat has occurred, individual cells in an embryo do not have coordinated movement of calcium. Instead they have what is called ‘spontaneous asynchronous calcium oscillations’ (SACOS). In this fellowship he plans to find out how SACOs are initiated in the developing embryo, by determining when the movement of calcium first starts to change in individual cells as the heart forms. He also hopes to understand how calcium moves in and out of cells and how this becomes synchronised to generate the coordinated movement that triggers the first heartbeat. This understanding is not only important for developmental biology and congenital heart disease but could also provide insight for regenerative therapies to help treat heart disease and heart rhythm disorders.