title: Ischemia-induced norepinephrine release, but not norepinephrine-derived free radicals, contributes to myocardial ischemia-reperfusion injury.
abstract: BACKGROUND
  Norepinephrine (NE)-derived free radicals may contribute to myocyte injury after ischemia -reperfusion, so the influence of sympathetic denervation on myocardial ischemia - reperfusion injury was investigated in the present study.
  
  
  RESULTS
  Cardiac sympathetic denervation was produced in Wistar rats by a solution of 10% phenol 1 week before ischemia. Atenolol (0.5 mg/kg) was intravenously administered 10 min before the coronary occlusion. The left coronary artery was occluded for 30 min and thereafter reperfused. Cardiac interstitial fluid was collected by a microdialysis probe and free radicals in dialysate were determined by electron paramagnetic resonance (EPR) spin trapping, using 5,5-dimethyl-1-pyrroline-N-oxide as a spin trap. The ratio of infarct size to the ischemic area at risk (I/R) was decreased in both the phenol and atenolol groups compared with control (28.5+/-11.3, 31.8+/-10.7 vs 50.6+/-14.7%, p<0.05). During the coronary occlusion, concentrations of interstitial NE increased markedly in the control and atenolol groups, but was unchanged in the phenol group. EPR signal intensity (relative value to internal standard) was maximal at 1 h after reperfusion and was similar in the phenol and control groups (0.32+/-0.15 vs 0.45+/-0.19).
  
  
  CONCLUSIONS
  Cardiac denervation protected myocyte against ischemia-reperfusion injury through decreasing direct NE toxicity, but not through decreasing NE-derived free radicals.
authors.affiliation: The Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Nonomura
authors.forename: Takashi
authors.initials: T
authors.lastname: Nozawa
authors.forename: Akira
authors.initials: A
authors.lastname: Matsuki
authors.forename: Teruo
authors.initials: T
authors.lastname: Nakadate
authors.forename: Norio
authors.initials: N
authors.lastname: Igarashi
authors.forename: Bun-ichi
authors.initials: B
authors.lastname: Kato
authors.forename: Nozomu
authors.initials: N
authors.lastname: Fujii
authors.forename: Akihiko
authors.initials: A
authors.lastname: Igawa
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Asanoi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000032:analysis / Q000378:metabolism*; D008297:Male; D017202:Myocardial Ischemia / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D005609:Free Radicals; D009638:Norepinephrine