[Present and future of the methods for measurement of intracellular Ca2+ concentration]

The development of fluorescent Ca2+ indicators, which have made measurement of the dynamic change in cytosolic free Ca2+ concentration during biological activity feasible, has allowed correlations to be drawn between biochemical changes within cells and their functions. Recently, many new types of Ca2+ indicators with special merit and also new methods for fluorescence measurement have been published. The present technical review summarizes properties of the newly developed indicators and describes the newly developed methods for measuring intracellular Ca2+ concentration. In particular, examples of image analysis applied to single cells and tissue slice preparations are stated in detail. Furthermore, a newly developed single optical fiber device for making measurements in the deep brain region is also introduced.