Figure 4.

Effect of extracellular Ca²⁺ on ATP-induced Ca²⁺ waves. (A) Ca²⁺ wave propagation induced by 500 nM ATP with 1.8 mM extracellular Ca²⁺. (B) Ca²⁺ wave propagation induced by 500 nM ATP with free extracellular Ca²⁺ and 0.4 mM EGTA in the same cell as in A. The initiation loci (arrows) were not affected with or without extracellular Ca²⁺. The images were made at intervals of 0.76 s. (Bar = 20 μm.)