[Construction of microfluorometer and its application for measuring intracellular free calcium]

A microfluorometer used for measuring intracellular free calcium has been constructed. This system was based on an XSJ-2 epifluorescence microscope with the following modifications. First, the AC mercury lamp was replaced by a DC xenon lamp to provide a stable light source. Second, an excitation filter wheel incorporating two interference filters was inserted in the light path allowing the biological sample to be excited alternately by lights of two different wavelength. The running of the whole system was under the control of a microcomputer. Such a system has successfully been used to monitor intracellular calcium changes with fluorescent calcium-sensitive dye Fura-2. Some examples of application are presented.