Figure 2.

(A) Mean fluorescence intensity (top trace) and line-scan image of subcellular Ca in atrial cells driven by the rapid pacing protocol. In this case, the line-scan position is chosen be in the longitudinal direction and as close to the cell center as possible. (B) Given here is an expanded image of Ca waves during rapid pacing. Ca transient, and a line-scan image of an atrial cell, were paced at 200 ms. The yellow arrows indicate wave sources that initiate bright waves that spread to the cell boundary, or collide with another wave. The red arrows indicate small wavelets that spread on the order of 10–20 μm. (C) Given here is a higher magnification of a line-scan image in a different cell sample. In some instances (red arrow), Ca wave sources are synchronized with the stimulation line. (D) Given here is a line-scan image of Ca in a dog HF cell paced with the rapid pacing protocol. (E) Shown here is a line-scan image of Ca under β-adrenergic stimulation. To see this figure in color, go online.