Heart beat irregularities are often lethal and can be caused by a group of overactive nerve cells (called stellate) located inside the chest. Removal of stellate cells in humans has been shown to stop life-threatening irregular heartbeats but this involves complex surgery, which is potentially life threatening itself. In both humans with heart disease and rats with susceptibility to heartbeat irregularity, we discovered a novel drug target or ‘receptor’ on these stellate cells which, when blocked, stops irregular heart beating. We propose to identify the precise makeup of this receptor (to refine drug targeting) and the type of stellate cell it resides on. Importantly, we will assess how this receptor makes the stellate cells overactive. In rats, we will use a novel drug to block this receptor to see if this safeguards against irregular heart beating. These studies could be translated to humans as a novel treatment for heartbeat irregularities.