title: Effects of ischemic preconditioning protocols on skeletal muscle ischemia-reperfusion injury.
abstract: BACKGROUND
  Ischemic preconditioning (IPC) is described as brief ischemia-reperfusion (I/R) cycles to induce tolerance to subsequent in response to longer I/R insults. Various IPC protocols can be performed in four combinations as follows: at early or late phases and on local or distant organs. Although many experimental studies have been performed on IPC, no consensus has been established on which IPC protocol is most effective. The aims of the present study were as follows: (1) to compare the variables of preconditioning in different combinations (in early versus late phases; local versus remote organ implementations) and (2) to determine the most therapeutic IPC protocol(s).
  
  
  METHODS
  A subtotal hind limb amputation model with clamping an intact femoral pedicle was used for I/R injury. IPC was induced using hind limb tourniquet with 3 × 10 min I/R cycles before longer I/R insult. Forty-nine rats were divided into seven groups (n = 7), sham, IsO (ischemia only), I/R, early ischemic preconditioning (e-IPC), late ischemic preconditioning (l-IPC), early remote ischemic preconditioning (e-RIPC), and l-RIPC (late-remote) groups, respectively. In the sham group, pedicle occlusion was not performed. Six hours ischemia was challenged in the IsO group. Three hours ischemia followed by 3 h reperfusion was performed in the I/R group. The e-IPC group was immediately preconditioned, whereas the l-IPC group was preconditioned 24 h before I/R injury on the same hind limb. In the e-RIPC and l-RIPC groups, the same protocols were performed on the contralateral hind limb. At the end of the experiments, skeletal muscle tissue samples were obtained for biochemical analysis (Malondialdehyde [MDA], catalase, myeloperoxidase [MPO], and nitric oxide end products [NOx]), light microscopy, and caspase-3 immunohistochemistry for determination of apoptosis.
  
  
  RESULTS
  Tissue biochemical markers were improved in nearly all the IPC groups compared with IsO and I/R groups (P < 0.05). Similarly, the histologic damage scores were decreased in all the IPC groups (P < 0.05). The lowest damage score was in the e-RIPC group followed by the l-RIPC, e-IPC, and l-IPC groups, respectively. The apoptosis scores were significantly high in the I/R group compared with the e-RIPC and l-RIPC groups (P < 0.05). Although apoptosis scores of the e-IPC and l-IPC groups were lower than the I/R group, this finding was not statistically significant (P > 0.05).
  
  
  CONCLUSIONS
  All IPC protocols were effective in reducing I/R injury. Among these protocols, e-RIPC achieved most protection.
authors.affiliation: Department of Plastic Reconstructive Aesthetic Surgery, Osmangazi University Faculty of Medicine, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey.
authors.forename: Emre A
authors.initials: EA
authors.lastname: Kocman
authors.affiliation: Osmangazi Center for In Vitro Fertilisation, Osmangazi University Faculty of Medicine, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey.
authors.forename: Orhan
authors.initials: O
authors.lastname: Ozatik
authors.affiliation: Department of Cardiovascular Surgery, Osmangazi University Faculty of Medicine, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey. Electronic address: draykutsahin@gmail.com.
authors.forename: Aykut
authors.initials: A
authors.lastname: Sahin
authors.affiliation: Department of Biochemistry, Osmangazi University Faculty of Medicine, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey.
authors.forename: Turkan
authors.initials: T
authors.lastname: Guney
authors.affiliation: Department of Plastic Reconstructive Aesthetic Surgery, Osmangazi University Faculty of Medicine, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey.
authors.forename: Aydan A
authors.initials: AA
authors.lastname: Kose
authors.affiliation: Osmangazi University High School for Vocational Health Services, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey.
authors.forename: Ilknur
authors.initials: I
authors.lastname: Dag
authors.affiliation: Department of Biochemistry, Osmangazi University Faculty of Medicine, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey.
authors.forename: Ozkan
authors.initials: O
authors.lastname: Alatas
authors.affiliation: Department of Plastic Reconstructive Aesthetic Surgery, Osmangazi University Faculty of Medicine, ESOGÜ Meşelik Yerleşkesi Eskişehir, Turkey.
authors.forename: Cengiz
authors.initials: C
authors.lastname: Cetin
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D005260:Female; D019194:Ischemic Preconditioning / Q000379:methods*; D035002:Lower Extremity / Q000098:blood supply* / Q000473:pathology; D008315:Malondialdehyde / Q000378:metabolism; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*
chemical_list: D009569:Nitric Oxide; D008315:Malondialdehyde; D002374:Catalase; D009195:Peroxidase; C505410:Casp3 protein, rat; D053148:Caspase 3
keywords: Ischemia–reperfusion (I/R) injury; Ischemic preconditioning (IPC); Skeletal muscle