Calcium is an important messenger in cells and whose store and diffusion dynamics at the subcellular level remain unclear. By inducing a controlled slow subcellular Ca2+ release through femtosecond laser irradiation in HeLa cells immersed in different media, cytoplasm is identified to be the major intracellular Ca2+ store, with the nucleus being the minor store and the extracellular Ca2+ also contributing to the total cellular Ca2+ level. Furthermore, Ca2+ released in either the cytoplasm or nucleus diffuses into the nucleus or cytoplasm, respectively, at different rates and influences the Ca2+ release in those regions.
Kam Tai Chan,
"Identification of source of calcium in HeLa cells by femtosecond laser excitation," Journal of Biomedical Optics 15(5), 057010 (1 September 2010). https://doi.org/10.1117/1.3485741