Figure 4. Dependence of changes in [Ca²⁺]_L on the concentration of InsP₃ added to weakly Ca²⁺-buffered media.

InsP₃ was applied to ICM pretreated with Chelex (A) or supplemented with 100 μM EGTA (B and C). Stepwise increases in InsP₃ elicited sustained decreases in [Ca²⁺]_L and [Ca²⁺]_L oscillations, whose frequencies are apparently independent of the [InsP₃] present. InsP₃ was added as indicated by the horizontal bars, numbers indicate the respective InsP₃ concentration in μm.