title: Expression of inducible nitric oxide synthase in muscle flaps treated with ischemic postconditioning.
abstract: OBJECTIVE
  Preconditioning has been considered promising for the treatment of ischemic flaps. In this study, the therapeutic effect of postconditioning was compared with that of preconditioning during ischemia/reperfusion (I/R) injury, and a role of inducible nitric oxide synthase (iNOS) in postconditioning treatment was also explored.
  
  
  METHODS
  Sixty rats were randomly divided into four groups with 15 rats in each group. Ischemic injury was induced in a rat's gracilis muscle flap model. Preconditioning and postconditioning were performed respectively on the flaps in the pre-con group and the post-con group. No treatment was given to the flaps in the control group, and flaps without I/R injury were used as a sham control. Muscle viability ratio, histology, and gene expression of iNOS were examined at different time intervals (3, 12, and 18 h).
  
  
  RESULTS
  A significantly higher survival ratio was observed in both the pre-con group (78.98 ± 3.39, 62.74 ± 3.7, and 54.42 ± 4.45 %) and the post-con group (77.42 ± 4.14, 59.74 ± 6.67, and 49.52 ± 4.13 %) than the control group (45.22 ± 3.69, 42.44 ± 3.76, and 33.2 ± 3.29 %) at 3, 12, and 18 h postoperatively (P < 0.05). There was no statistical difference between the pre-con group and the post-con group (P > 0.05). Histological examination showed delayed and attenuated tissue damage in both the pre-con group and the post-con group when compared to that of the control group. A higher expression of iNOS was observed in both the pre-con group and the post-con group than the control group and the sham group (P < 0.05).
  
  
  CONCLUSIONS
  Significant improvement of flap survival could be achieved by both preconditioning and postconditioning treatments; however, better protection could be provided by preconditioning. The higher expression of iNOS may play an important role in the therapeutic effect of postconditioning during I/R injury.
authors.affiliation: Division of Plastic Surgery, Southern Illinois University School of Medicine, Springfield, IL USA.
authors.forename: Mei
authors.initials: M
authors.lastname: Yang
authors.forename: Michael F
authors.initials: MF
authors.lastname: Angel
authors.forename: Yi
authors.initials: Y
authors.lastname: Pang
authors.forename: John J
authors.initials: JJ
authors.lastname: Angel
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.forename: Michael W
authors.initials: MW
authors.lastname: Neumeister
authors.forename: Nathan
authors.initials: N
authors.lastname: Wetter
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
keywords: Inducible nitric oxide synthase; Ischemia/reperfusion (I/R) injury; Ischemic postconditioning; Ischemic preconditioning