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Figure 5 (A) Ryanodine receptor 2 (RyR2) immunoblots (lower panel) and back phosphorylation gels. For the latter, the darker bands correspond to higher amounts of 32P transferred to RyR2 by protein kinase A (PKA), which is indicative of reduced RyR2 PKA phosphorylation in vivo. Note double band present in right ventricle (RV) RyR2 immunoblot. There is no special significance to the double bands in the RyR2 samples from the RV—moreover, given that the samples from nonfailing, medically, and left ventricular assist device (LVAD)-supported hearts are all equivalent (equal densities of the top and bottom bands) indicates that these samples are comparable and that measurements of the PKA phosphorylation levels are not affected by the presence of the two bands. Moreover, this does not represent nonspecific degradation as that would result in a smear. (B) RyR2 phosphorylation was markedly increased in failing myocardium, but was normalized by LVAD support in both ventricles. *p < 0.01 vs. nonfailing and LVAD-supported hearts. LV = left ventricle; HF = heart failure; PKI = protein kinase A inhibitor.