Fig. 5. Activation of MS channels in the vicinity of FAs by mechanical stimulation. Time-lapse imaging of the increase in [Ca²⁺]_i at a time resolution of 17 milliseconds (A) and a 2 millisecond snapshot image of the [Ca²⁺]_i increase (B). (A) The FN bead was displaced by 1 µm in the direction indicated by the arrow (a). The distribution of FAs was imaged by interference reflection contrast microscopy; green spots denote the FAs (b). (c-g) A series of time-lapse images of the increase in [Ca²⁺]_i caused by the mechanical stimulation. (h) Superimposed images of b and d (green, FAs; red, [Ca²⁺]_i increase). The white arrows indicate FAs inside of the area of the [Ca²⁺]_i increase. (B) DIC (a, upper) and TIRF (a, lower) images of a cell at low magnification. The area enclosed by the white dotted rectangle in a is magnified in b. Regions of high [Ca²⁺]_i ([Ca²⁺]_i microdomains) 2-4 milliseconds after the onset of the stimulation are shown as red spots. These spots are located in the vicinity of integrin clusters (green). The upper left panel in b shows approximately 10 [Ca²⁺]_i microdomains. The middle left panel shows β1 integrin and the lower left panel shows an overlay of the [Ca²⁺]_i microdomain and the integrin. The right-hand panels in b show another example of the [Ca²⁺]_i microdomains 0-2 milliseconds after the onset of the stimulation. The graph in c shows the intensity profiles of fluo-3 and anti-β1-integrin fluorescence in the region denoted by the yellow line in the lower left panel in b.