title: The effect of ischemia-reperfusion injury on measures of vascular function.
abstract: BACKGROUND
  Ischemia-reperfusion injury results in conduit vessel endothelial dysfunction as assessed by flow-mediated dilatation (FMD). The effect on the potentially more important microvascular circulation has not been well studied. The objective of our study was to assess the effect of ischemia-reperfusion injury on microvascular function including peripheral arterial tonometry (PAT) hyperemic index.
  
  
  METHODS
  45 healthy volunteers free of cardiovascular disease were recruited (mean age 35 ± 14 yrs, 29 men). Using ultrasound, the flow-mediated dilation (FMD) and hyperemic velocity (VTI) of the brachial artery were measured following a 5-minute forearm cuff occlusion. Simultaneously, the PAT hyperemic index was measured. Ischemia was then induced by a 15-minute upper arm occlusion and within 15 minutes of recovery the vascular measures were repeated.
  
  
  RESULTS
  Ischemia caused a significant reduction in FMD (7.9 ± 4.0 to 4.7 ± 3.5, p = 0.0001). The hyperemic VTI, a measure of microvascular function, was unaffected following ischemia-reperfusion (92 ± 30 vs. 97 ± 37 cm, p = 0.236). Finally, PAT index was also unchanged by the intervention (2.07 ± 0.8 vs. 2.04 ± 0.7, p = 0.742).
  Ischemia-reperfusion caused conduit and not resistance vessel endothelial dysfunction. The PAT-index was unchanged suggesting that this measure is more closely aligned with resistance than conduit vessel function. This has implications for its use as a measure of vascular function in clinical research.
authors.affiliation: Department of Cardiac Sciences and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada.
authors.forename: Wesam
authors.initials: W
authors.lastname: Alhejily
authors.affiliation: Department of Cardiac Sciences and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada.
authors.forename: Alda
authors.initials: A
authors.lastname: Aleksi
authors.affiliation: Department of Cardiac Sciences and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada.
authors.forename: Billie-Jean
authors.initials: BJ
authors.lastname: Martin
authors.affiliation: Department of Cardiac Sciences and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Anderson
mesh_terms: D000328:Adult; D001916:Brachial Artery / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D015427:Reperfusion Injury / Q000097:blood* / Q000235:genetics / Q000378:metabolism*
keywords: Endothelial dysfunction; Ischemic reperfusion injury (IR); and microvascular; flow-mediated dilation (FMD)