Figure 5.

I_Cl(Ca) is sustained in the presence of a sustained rise in [Ca²⁺]_i if CaMKII phosphorylation is inhibited. Ionomycin was used to produce a sustained rise in [Ca²⁺]_i as in Fig. 4. In cells dialyzed with AMP-PNP (Upper Left), with ATP and the CaMKII antagonist KN93 (Upper Right), or with ATP and the CaMKII inhibitory peptide fragment (Upper Left), I_Cl(Ca) achieved a peak value and was sustained. Conversely, dialysis of cells with ATP and H7, which has a low affinity for CaMKII, did not prevent the decay of I_Cl(Ca). All cells were dialyzed for 5 min and were voltage-clamped at −60 mV.