title: Role of nitric oxide in intestinal ischaemia-reperfusion injury studied using electron paramagnetic resonance.
abstract: BACKGROUND
  The role of nitric oxide in intestinal ischaemia-reperfusion (I/R) remains poorly defined, partly because of difficulty in detecting the nitric oxide free radical. In this study nitric oxide production was assessed during intestinal I/R by direct measurement using electron paramagnetic resonance (EPR), and the production of nitric oxide in jejunum and ileum was correlated with their different abilities to resist I/R injury.
  
  
  METHODS
  Rats were given an electron spin trapper (diethyldithiocarbamate/ferrous citrate) by intraperitoneal injection. Thirty-six segments each of jejunum and ileum were subjected to 15-90 min of ischaemia and 25 min of reperfusion. Tissue samples were analysed for EPR signals using a spectrometer.
  
  
  RESULTS
  Mean(s.d.) basal nitric oxide level was significantly higher in ileum (3.39(1.42) units) than jejunum (0. 65(0.05) units) (P = 0.0005). Increasing ischaemic times in the ileum resulted in decreasing nitric oxide levels (85, 32 and 13 per cent of basal level at 30, 60 and 90 min respectively); reperfusion resulted in further nitric oxide reduction (mean decrease 26 per cent). Severe (grade 3) histological damage was observed in low nitric oxide states (after 15 min of I/R in jejunum, 60 min of I/R in ileum).
  
  
  CONCLUSIONS
  Nitric oxide can be measured in intestinal tissues directly by EPR. The findings support a protective role for nitric oxide in I/R, and offer an explanation for the greater resistance to I/R of ileum.
authors.affiliation: Department of Surgery, University of Hong Kong Medical Centre, Queen Mary Hospital, Hong Kong, China.
authors.forename: K L
authors.initials: KL
authors.lastname: Chan
authors.forename: X H
authors.initials: XH
authors.lastname: Zhang
authors.forename: P C
authors.initials: PC
authors.lastname: Fung
authors.forename: W H
authors.initials: WH
authors.lastname: Guo
authors.forename: P K
authors.initials: PK
authors.lastname: Tam
mesh_terms: D000818:Animals; D007082:Ileum / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008854:Microscopy, Electron; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism*
chemical_list: D009569:Nitric Oxide