A, c-Kitpos CSC number was elevated in the myocardium after ISO administration. *, p < 0.05 versus CTRL (B). The percentage of c-Kitpos CSCs positive for the cell cycle marker, Ki67, increased after ISO injection, peaking at 1 day. *, p < 0.05 versus CTRL. C, representative immunohistochemistry staining of c-Kitpos/Ki67pos CSCs in ISO-treated rat myocardium (c-Kit (green), Ki67 (white), α-sarcomeric actin (red), and DAPI (blue)). D, ISO exposure had no effect on CSC proliferation, measured by bromodeoxyuridine incorporation, in vitro (p = not significant).