title: Microvascular changes following four-hour single arteriole occlusion.
abstract: BACKGROUND
  Free tissue transplantations are lengthy procedures that result in prolong tissue ischemia. Restoral of blood flow is essential for free flap recovery; however, upon reperfusion tissue that is viable may continue to be nonperfused. To further elucidate this pathophysiology skeletal muscle microcirculation was investigated during reperfusion following 4-hour single arteriole occlusion.
  
  
  METHODS
  A blunt micropipette probe was use to compress a single arteriole in the unanesthetized hamster (N = 20) dorsal skinfold chamber. Arteriole (n = 20), capillary (n = 97), and postcapillary venule (n = 16) diameters and blood flow were analyzed at 0, 30, 60, 120, 240 min and 24 hours of reperfusion after 4 hour occlusion.
  
  
  RESULTS
  Feeding arcade arterioles exhibited a brief (<10 min) vasoconstriction [0.31 ± 0.26 (mean ± SE) of baseline] upon reperfusion followed by a maximum vasodilation at 120 min (1.3 ± 0.10: P < 0.05). Vasodilation was observed in transverse arterioles (A3) (1.8 ± 0.20: P < 0.05). Correspondingly, all arteriole and venule flow was increased by 120 min (P < 0.05) of reperfusion. There was a transient decrease in the number of flowing capillaries at 0 and 30 min reperfusion (0.73 ± 0.09 and 0.84 ± 0.06: P < 0.05, respectively).
  
  
  CONCLUSIONS
  At the onset of reperfusion heterogeneous arteriole flow and transient decrease in flowing capillaries was observed; however, return of flow in all capillaries and an eventual hyperemic response in all arterioles suggests the reversible nature of this response. Single arteriole occlusion may allow for a more controlled and detailed microcirculatory analysis during ischemia-reperfusion.
authors.affiliation: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA. dsaltzman@mednet.ucla.edu
authors.forename: Darin J
authors.initials: DJ
authors.lastname: Saltzman
authors.forename: Heinz
authors.initials: H
authors.lastname: Kerger
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Jimenez
authors.forename: Dina
authors.initials: D
authors.lastname: Farzan
authors.forename: James M
authors.initials: JM
authors.lastname: Wilson
authors.forename: Jesse E
authors.initials: JE
authors.lastname: Thompson
authors.forename: Marcos
authors.initials: M
authors.lastname: Intaglietta
mesh_terms: D000818:Animals; D001160:Arterioles; D006224:Cricetinae; D058752:Free Tissue Flaps / Q000098:blood supply; D008297:Male; D055806:Microvessels / Q000473:pathology* / Q000503:physiopathology*; D012039:Regional Blood Flow; D013997:Time Factors; D014656:Vascular Surgical Procedures / Q000379:methods