title: Ischemia-reperfusion impairs ascending vasodilation in feed arteries of hamster skeletal muscle.
abstract: OBJECTIVE
  Vasodilation originating within the microcirculation ascends into proximal feed arteries during muscle contraction to attain peak levels of muscle blood flow. Ascending vasodilation (AVD) requires an intact endothelium, as does conducted vasodilation in response to acetylcholine (ACh). Whereas ischemia-reperfusion (I-R) can affect endothelial cell function, the effect of I-R on AVD is unknown. The authors tested the hypothesis that I-R (1h-1h) would impair AVD.
  
  
  METHODS
  Using the retractor muscle of anesthetized hamsters, contractions were evoked using field stimulation (200 ms at 40 Hz every 2 s for 1 min) and ACh was delivered using microiontophoresis (1 microm tip, 500-4000 ms pulse at 800 nA). Feed artery responses were monitored 500-1500 microm upstream.
  
  
  RESULTS
  Neither resting (51 +/- 4 microm) nor maximal diameter (81 +/- 5 microm; 10 microm sodium nitroprusside) following I-R (n = 8) were different from time-matched controls (n = 10). With peak active tension of 23 +/- 4 mN x mm(-2), control AVD was 26 +/- 2 microm. Following I-R, active tension fell by 48% (p < .05) and AVD by 57% (p < .05). Stimulation at 70 Hz restored active tension but AVD remained depressed by nearly half (p < .05), as did local and conducted responses to ACh. Nevertheless, control responses to 500 ms ACh were restored by increasing stimulus duration to 4000 ms.
  
  
  CONCLUSIONS
  Ischemia-reperfusion impairs the initiation of feed artery dilation with muscle contraction and with ACh while conduction along the vessel wall is preserved. Respective components of endothelial cell signaling events may differ in their susceptibility to I-R.
authors.affiliation: The John B Pierce Laboratory and Yale University, New Haven, Connecticut 06519, USA.
authors.forename: Miriam C J
authors.initials: MC
authors.lastname: de With
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Haug
authors.forename: E P A
authors.initials: EP
authors.lastname: Brigitte van der Heijden
authors.forename: Steven S
authors.initials: SS
authors.lastname: Segal
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000187:drug effects; D006224:Cricetinae; D042783:Endothelial Cells / Q000378:metabolism; D004727:Endothelium / Q000503:physiopathology; D008297:Male; D008647:Mesocricetus; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000503:physiopathology; D015427:Reperfusion Injury / Q000503:physiopathology*; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D000109:Acetylcholine