Figure 4. Effect of cytosolic Ca²⁺ buffering on the spatial organisation of the transients induced by high [K⁺] and caffeine.

The red, green and blue traces show the [Ca²⁺]_i changes measured in the regions marked with the corresponding colours on the cell profile at the top. Loading of myotubes with BAPTA reduced the amplitude of the Ca²⁺ response to 40 mM K⁺ but did not affect the spatial aspects. In contrast, Ca²⁺ buffering of the cytosol abolished the typical Ca²⁺ wave in response to caffeine (Caff); this was replaced by a synchronous and moderate elevation of [Ca²⁺]_i. Scale bar, 25 μm.