FIGURE 6. Adult c-Kit^pos CSCs are resistant to the damaging effects of ISO.

A and B, representative immunostaining showing apoptotic CSCs (c-Kit (red), TdT (green), and DAPI (blue)) in CTRL (A) and ISO-treated (B) CSCs in vitro. C, isolated c-Kit^pos CSCs exposed to the same doses of ISO as ARVMs (Fig. 4C) were 2 orders of magnitude more resistant. Subsequently, only the highest dose of ISO (10 μm) caused significant CSC apoptosis. *, p < 0.01 versus CTRL and AA alone. D, the specific β₁-AR blocker, CGP20172A (0.3 μm), attenuated CSC apoptosis. E, in contrast, in the presence of a specific β₂-AR blocker (ICI 118551; 0.1 μm) CSC apoptosis increased with ISO dose. F and G, representative Western blot and quantitative real time RT-PCR results showing the absence of RyR2 in c-Kit^pos CSCs when compared with ARVMs. Data are presented as the ratio between numbers of RyR2 and GAPDH mRNA molecules per μg of RNA. *, p < 0.01 versus ARVMs.