title: Effects of ischemic pre- and postconditioning on HIF-1α, VEGF and TGF-β expression after warm ischemia and reperfusion in the rat liver.
abstract: BACKGROUND
  Ischemic pre- and postconditioning protects the liver against ischemia/reperfusion injuries. The aim of the present study was to examine how ischemic pre- and postconditioning affects gene expression of hypoxia inducible factor 1α (HIF-1α), vascular endothelial growth factor A (VEGF-A) and transforming growth factor β (TGF-β) in liver tissue.
  
  
  METHODS
  28 rats were randomized into five groups: control; ischemia/reperfusion; ischemic preconditioning (IPC); ischemic postconditioning (IPO); combined IPC and IPO. IPC consisted of 10 min of ischemia and 10 min of reperfusion. IPO consisted of three cycles of 30 sec. reperfusion and 30 sec. of ischemia.
  
  
  RESULTS
  HIF-1α mRNA expression was significantly increased after liver ischemia compared to controls (p = 0.010). HIF-1α mRNA expression was significantly lower in groups subjected to IPC or combined IPC and IPO when compared to the ischemia/reperfusion group (p = 0.002). VEGF-A mRNA expression increased in the ischemia/reperfusion or combined IPC and IPO groups when compared to the control group (p < 0.05).
  
  
  CONCLUSIONS
  Ischemic conditioning seems to prevent HIF-1α mRNA induction in the rat liver after ischemia and reperfusion. This suggests that the protective effects of ischemic conditioning do not involve the HIF-1 system. On the other hand, the magnitude of the HIF-1α response might be a marker for the degree of I/R injuries after liver ischemia. Further studies are needed to clarify this issue.
authors.affiliation: Department of Surgical Gastroenterology L, Aarhus University Hospital, Aarhus, Denmark. auknudsen@gmail.com.
authors.forename: Anders R
authors.initials: AR
authors.lastname: Knudsen
authors.forename: Anne-Sofie
authors.initials: AS
authors.lastname: Kannerup
authors.forename: Henning
authors.initials: H
authors.lastname: Grønbæk
authors.forename: Kasper J
authors.initials: KJ
authors.lastname: Andersen
authors.forename: Peter
authors.initials: P
authors.lastname: Funch-Jensen
authors.forename: Jan
authors.initials: J
authors.lastname: Frystyk
authors.forename: Allan
authors.initials: A
authors.lastname: Flyvbjerg
authors.forename: Frank V
authors.initials: FV
authors.lastname: Mortensen