Updated project metadata. The overall goal of the project was to confirm the presence of different energetic states of mitochondrial subpopulations depending on their subcellular localization within cardiomyocytes, i.e., subsarcolemmal (SSM) and interfibrillar mitochondria (IFM). At the same time, we aimed to elucidate possible respiratory plasticity of mitochondrial states in response to oxygen availability because of treatment with hyperbaric oxygen. The results could form the basis for a more efficient therapy of contractile dysfunction of the heart but also of other diseases if they are due to mitochondrial respiratory dysfunction caused by a lack of tissue oxygenation.