Figure 5.

Ca²⁺ spark restitution and cellular Ca²⁺ transients after β-adrenergic stimulation combined with PKA or CAMKII inhibition

A, Ca²⁺ spark amplitude restitution (top) and spark-to-spark delay histogram (bottom) for different conditions (columns): (1) ISO (100 nm) + KN92 (1 μm), an inactive CaMKII inhibitor; (2) ISO + KN93 (1 μm), a CaMKII inhibitor; (3) ISO + H89 (1 μm), a PKA inhibitor; (4) CTRL (replotted from Fig.1 for comparison). Bold lines show fit to the data of exponential recovery curves with indicated time constant and number of spark pairs. Histogram binning is 100 ms; N refers to number of spark pairs in each group. Experiments performed in presence of 50 nm ryanodine to induce repetitive Ca²⁺ sparks. B, whole cell Ca²⁺ transient statistics in (1) ISO + KN92 (recorded from 15 and 13 cells, respectively); (2) ISO + KN93 (recorded from 17 and 12 cells, respectively); (3) ISO + H89 (recorded from 21 and 19 cells, respectively); (4) CTRL (recorded from 20 and 15 cells, respectively). If not indicated otherwise, P < 0.01 (NS, not significant).