Figure 2. ATX-II induced Ca²⁺ mishandling is reversed by antioxidants or CaMKII inhibition.

A. Line-scan confocal images of Ca²⁺transients recorded from paced adult rabbit cardiomyocytes. The antioxidants CoQ10 (10μM) and DTT (10mM) or the CaMKII inhibitors, AIP (1 μM) or KN-93 (3) μM), were applied after induction of arrhythmic Ca²⁺ transients with 5 nM ATX-II. Treatment with antioxidants or CaMKII inhibitors restored normal Ca²⁺ dynamics and attenuated arrhythmic Ca²⁺ transients. KN-92 (3 μM) was used as a negative control for KN-93. B. Quantification of i) diastolic Ca²⁺, and ii) number of cells with arrhythmic Ca²⁺ transients (%). N=4-24; * p<0.05 vs control; †P<0.05 vs ATX-II alone. C. Western blots for oxidation of CaMKII at Met281/282 (ox-CaMKII), phosphorylation of CaMKII at Tyr287 (p-CaMKII), phosphorylation of RyR2s at Ser2814 (p-RyR2) and phosphorylation of PLN at Thr17 (p-PLN). Cardiomyocytes were treated with 5 nM ATX-II, in the absence and presence of antioxidants CoQ10 (10 (μM), DTT (10 (μM), the CaMKII inhibitor KN-93 (3 μM) and the inactive analog, KN92 (3 μM). D. Western Blot quantification, normalized to GAPDH (N=3, * p<0.05 vs control and † p<0.05 vs ATX-II alone).