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). Conclusion: 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.