Calcium imaging

Calcium (Ca) is one of the most relevant ions in the body as it is essential for e.g. the accurate timing and function of interneuronal communication or cardiomyocytes. In a physiological system, intracellular and extracellular Ca concentrations ([Ca]) are usually not in equilibrium and the concentration gradient is maintained by the cell with a very complex system of ion channels and transporters. Furthermore, the Ca signals can vary dramatically depending on the localization within a cell, e.g the cytosol, within mitochondria or the endoplasmic reticulum. The global, cytosolic Ca signal in a neuron is in the ballpark of 100 nM, whereas it is in the high M range just behind an open voltage-gated Ca channel when Ca flows into the cell following the gradient. The importance of Ca in physiological systems makes it a very active area of research and it is crucial to be able to monitor Ca dynamics in a reliable manner. Therefore, the choice of calcium indicator is an important consideration.