title: The effect of postconditioning on the muscle flap survival after ischemia-reperfusion injury in rats.
abstract: BACKGROUND
  Timely recognition of vascular compromise of free flaps is crucial to salvaging failing flaps due to the vulnerability of muscle tissues to ischemia. The concept of postconditioning (post-con) that has been introduced as an “after injury" strategy may be beneficial to salvage the failing muscle flaps. We aim to investigate the effect of post-con on the muscle flap survival after ischemia-reperfusion (I/R) injury in rats.
  
  
  METHODS
  The gracilis muscle flap model was used and a complete 4 hr of ischemia was generated by occlusion of the pedicle of dissected flap. The post-con procedure was started at the end of ischemia with six cycles of 15 s of reperfusion, followed by 15 s of complete reocclusion prior to the unlimited reperfusion. Muscle edema, malondialdehyde (MDA) level, muscle viability, and different time intervals (0, 3, 6, 18 hr) of gene expression of VEGF post-perfusion were assessed.
  
  
  RESULTS
  Significant difference in muscle viability was noted between the post-con group and the control group (4 hr of ischemia followed by full reperfusion without intervention) in spite of being noncomparable with the sham group (no ischemic exposure) 3 days postoperatively. Statistically decreased muscle edema and MDA level were observed in the post-con group compared with the control group. Histological study also showed that attenuated inflammatory reaction was observed in the post-con group compared with the control group. A relatively higher level of VEGF since 3-hr post-reperfusion in the post-con group compared with the control and sham groups was recorded.
  
  
  CONCLUSIONS
  Our results indicate that post-con procedure effectively reduces I/R injury and improves the survival of muscle flaps after ischemia. The consistent expression of VEGF in a high level may play an important role in the physiological effects of post-con.
authors.affiliation: Division of Plastic Surgery, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA.
authors.forename: Hede
authors.initials: H
authors.lastname: Yan
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Kochevar
authors.forename: Ovunc
authors.initials: O
authors.lastname: Akdemir
authors.forename: Weiyang
authors.initials: W
authors.lastname: Gao
authors.forename: Michael
authors.initials: M
authors.lastname: Angel
mesh_terms: D000818:Animals; D057775:Ischemic Postconditioning; D008297:Male; D008315:Malondialdehyde / Q000032:analysis; D018482:Muscle, Skeletal / Q000098:blood supply / Q000473:pathology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000517:prevention & control*; D013524:Surgical Flaps / Q000473:pathology / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D008315:Malondialdehyde