Small bowel ischaemia-reperfusion increases plasma concentrations of oxidised proteins in rats

Objectives. To find out whether plasma concentrations of protein carbonyl (a specific marker of oxidative damage of proteins) are increased during intestinal ischaemia-reperfusion and whether they are correlated with yon Willebrand's factor (vWF, a marker of endothelial injury) or myeloperoxidase (a marker of neutrophil activation). Design. Randomised experimental study. Setting. University department of surgery, New Zealand. Animals. Thirty anaesthetised adult Wistar rats. Interventions. The sham operated group (n = 10) had laparotomy and isolation of the superior mesenteric artery without clamping. The ischaemia-reperfusion group (IR, n = 10) had the superior mesenteric artery clamped for 1 hour and reperfusion for 15 minutes. The control group (n = 10) had direct puncture of the heart to sample blood. Main outcome measures. Plasma concentrations of protein carbonyl, vWF, and myeloperoxidase. Results. Plasma protein carbonyl concentrations were significantly higher in the IR group than in the sham group (p<0.02, Mann-Whitney test, median (range) 0.187 (0.141-0.242) compared with 0.144 (0.121-0.185) nmol/mg) and in the control group (p <0.01, Mann- Whitney test, median (range) 0.187 (0.141-0.242) compared with 0.136 (0.108- 0.175) nmol/mg). There was a significant correlation between protein carbonyl and vWF concentrations (r = 0.54, F = 10.9, p<0.003, linear regression) but not with those of myeloperoxidase. Conclusion. Intestinal ischaemia- reperfusion caused an increase in the plasma protein carbonyl concentration, which is possibly produced by endothelial cells.