Figure 3.

SERCA inhibition by polyarginine CPPs is not dependent on phospholamban. Oxalate-supported Ca²⁺ uptake and SR Ca²⁺ leak were examined in homogenates isolated from the left ventricles of PLB knockout (KO) mice. Comparison was made between untreated homogenates (Ctr) and homogenates incubated with TAT, Arg₉, or Arg₁₁ in the absence (A) or presence (B) of attached, scrambled cargo. Ca²⁺ uptake, leak, and releasable Ca²⁺ were assessed, as described in Figure 2 (see Methods). Data are presented as mean ± SEM. Statistical analyses were performed by one-way ANOVA with Tukey’s post hoc correction. p values are indicated versus Ctr. NS = not statistically significant. n_runs in Ctr, TAT, Arg₉, Arg₁₁ = 58, 12, 17, 15; n_runs in Ctr, Arg₉-cargo, Arg₁₁-cargo = 58, 9, 10 in homogenates from 9 hearts.