Molecular oxygen (O 2 ) is one of the most functionally relevant metabolites. O 2 is essential for mito-chondrial aerobic respiration. Changes in O 2 affect muscle metabolism and play a critical role in the maintenance of skeletal muscle mass, with lack of sufficient O 2 resulting in detrimental loss of muscle mass and function. How exactly O 2 is used by muscle cells is less known, mainly due to the lack of tools to address O 2 dynamics at the cellular level. Here we discuss a new imaging method for the real time quantification of intracellular O 2 in muscle cells based on a genetically encoded O 2 -responsive sensor, Myoglobin-mCherry. We show that we can spatially resolve and quantify intracellular O 2 concentration in single muscle cells and that the spatiotemporal O 2 gradient measured by the sensor is linked to, and reflects, functional metabolic changes occurring during the process of muscle differentiation.
Highlights: Real time quantitation of intracellular oxygen with spatial resolutionIdentification of metabolically active sites in single cellsOxygen metabolism is linked to muscle differentiation.