Fig. 1. Simultaneous measurements of the resting potential and intracellular Ca²⁺ concentration ([Ca²⁺]_i). (A) A composite image from a synchroscope and a fluorescence microscope. Both images from the synchroscope and fluorescence microscope indicate resting potential and [Ca²⁺]_I, respectively, and are joined to form a single image. The bottom right of the fluorescence cellular image is the anterior side of the cell. (B) Fluctuations of resting potential and fluorescence intensity (FI). (i) Fluctuation of resting potential. Time average of membrane potential is shown as zero. (ii) Fluctuation of fluorescence intensity measured across the whole cell area. Fluorescence intensity was normalized using the time average of fluorescence intensity for the whole cell area. Changes from the average are shown. (iii) Fluctuation of fluorescence intensity measured across the anterior half of the cell. Fluorescence intensity was normalized using the time average of fluorescence intensity of the anterior half of the cell. (iv) Fluctuation of fluorescence intensity measured across the posterior half of the cell. Fluorescence intensity was normalized using the time average of fluorescence intensity of the posterior half of the cell. Above data represent data obtained from a single cell.