Photorelease technique of Ca²⁺ can manipulate intracellular calcium concentation (［Ca²⁺］_i) by photolyzing specific photosensitive Ca²⁺ chelator in the cell to change its affinity with Ca²⁺. This technique is especially useful in elucidating the intracellular messenger role of Ca²⁺ in cell functions such as electrical excitability, muscle contraction and secretion, etc.