SDF-1 regulation in adductor muscle following ischemia. (A) Semiquantitative RT-PCR using RNA obtained from an RNA pool of at least 3 animals at each indicated time point showed an up-regulation of the SDF-1 mRNA above control peaking at day 3 following ischemia. Up-regulation of SDF-1 mRNA above control is evident starting 6 hours following induction of ischemia. (B) Negative control for SDF-1 immunohistochemistry in tissue sections of normoperfused mice. (C-E) Immunohistochemistry of SDF-1 in adductor muscles of normoperfused mice. Expression of SDF-1 was generally very low (C), but expressed in satellite cells of some small muscle fibers (D). In nonischemic muscles SDF-1 was also expressed, although at low levels, in arterioles (E). (F-G) At 6 hours after ischemia, SDF-1 was up-regulated in arterioles (F) and muscle fibers associated to infiltrating cells showing strong immunoreactive staining (G). (H-I) At day 3, a strong up-regulation in SDF-1 protein expression was observed in the adductor muscle both at arteriole (H) and muscle fibers levels (I). (J) SDF-1 was expressed in regenerating muscle fibers, showing centrally located nuclei, at 7 days after ischemia.