FIGURE 4.

Sparks imaged in intact mouse cardiomyocytes with the optical bilayer system. A x-t line scan image of sparks in an intact ventricular cardiomyocyte bathed in 1 mM Ca²⁺ is shown. Myocytes were permitted to settle onto laminin-coated coverslips, which were fixed to the surface of the trans chamber in place of the bilayer partition. The trans chamber was positioned as for a bilayer experiment and the optical system was identical to that used to image Ca²⁺ fluxes across the bilayer. Intensity-time traces for the sparks numbered as indicated on the left side of the image are shown in the lower part of the figure. Cumulative data for the properties of sparks imaged in intact myocytes are presented in Table 1.