title: The effects of acute and intermittent hypoxia on the expressions of HIF-1α and VEGF in the left and right ventricles of the rabbit heart.
abstract: OBJECTIVE
  Hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) are involved in signaling mechanisms of cellular responses to hypoxia. These factors have been investigated in tissue samples by simulating different altitudes by changing the percentage of oxygen. We aimed first to evaluate the effect of normobaric, systemic hypoxia (11% O2) on HIF-1α and VEGF mRNA levels in the heart muscle; secondly, to compare the levels of HIF-1α and VEGF mRNA in the left and right ventricle muscles.
  
  
  METHODS
  In this experimental study, 33 New Zealand male rabbits were assigned to control, acute hypoxia (4 hours) and intermittent hypoxia (4 hours/day for 14 days) groups (n=11/group). Total RNA was isolated from right and left ventricles of the heart. The expressions of HIF-1α and VEGF mRNAs were investigated by using Reverse Transcription Polymerase Chain Reaction (RT-PCR) method. The obtained data were compared by using ANOVA and paired t-test.
  
  
  RESULTS
  The results indicated that left ventricle VEGF mRNA expressions in both acute and intermittent hypoxia groups (1.08 ± 0.15 and 1.03 ± 0.19, respectively) were higher than that in the control group (0.88 ± 0.15) (p=0.03). Hypoxia treatments did not significantly alter HIF-1α mRNA in both ventricles (p=0.60 and p=0.51 for left and right ventricles, respectively).
  
  
  CONCLUSIONS
  Since systemic hypoxia results in induction of VEGF mRNA up-regulation only in left ventricle, it could be related to its higher metabolic activity and oxygen utilization. Hypoxia induced changes in the expression of HIF-1α mRNA may not be the only determining factor for HIF-1/VEGF pathway induction or the observed VEGF induction could be through other hypoxia sensitive pathways.
authors.affiliation: Department of Physiology, Faculty of Medicine, Ankara University, Ankara-Turkey.
authors.forename: Demet
authors.initials: D
authors.lastname: Tekin
authors.forename: Ali Doğan
authors.initials: AD
authors.lastname: Dursun
authors.forename: Metin
authors.initials: M
authors.lastname: Baştuğ
authors.forename: Gökhan
authors.initials: G
authors.lastname: Karaorman
authors.forename: Hakan
authors.initials: H
authors.lastname: Fıçıcılar
mesh_terms: D000818:Animals; D004587:Electrophoresis, Agar Gel; D015870:Gene Expression; D006352:Heart Ventricles / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism*; D011817:Rabbits; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A