While intracellular calcium release is essential as a rapid signaling mechanism for cardiac regulation, alterations cause atrial fibrillation and strokes. The central mechanism underlying calcium signaling in atrial myocytes, however, is not fully understood. An international research project led by Prof. Stephan Lehnart’s team at the University of Göttingen has identified for the first time an atrium-specific mechanism for extremely rapid atrial muscle contraction, whereby large axial membrane structures deep inside the cell selectively activate calcium signals via phosphorylated RyR2 release channels. Elevated blood pressure in the atrium, on the other hand, leads to marked pathological changes in the atrial cells, the RyR2 channels and in calcium release. These studies support not only completely new cell-specific functional mechanisms, they furthermore imply therapeutic, particularly drug-accessible treatment approaches to atrial pathologies and changes in chronic hypertension.